srp861 dairy day 2000lines and test conditions to define acceptable limits for the pi test....

This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

2000 Dairy Day Program

10:00 a.m./3:00 p.m. Registration

10:25 a.m./3:25 p.m. Welcome

Lunch/Dinner Courtesy of the Kansas Dairy Association (KDA)

Topics to be presented:

“Milk Quality from the Processor’s Point of View” . . . . . . . . . . . . . . . . Dr. Karen Schmidt

“Mastitis Management-Effective Methods to ReduceSomatic Cell Counts” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dr. Mike Brouk

“Important Silage Practices Often Overlooked” . . . . . . . . . . . . . . . . . . . . Dr. Keith Bolsen

“Update of Nutritional Research at K-State” . . . . . . . . . . . . . . . . . . . . . . . . Dr. John Shirley

2:30 p.m./8:00 p.m. Adjourn

Locations:

Thursday November 9 3:00-8:00 p.m. Garden City 4-H Building

Wednesday November 15 10:00 a.m.-2:30 p.m. Seneca Valentino’s

Thursday November 16 10:00 a.m.-2:30 p.m. Whiteside Amish CommunityBuilding

Friday November 17 10:00 a.m.-2:30 p.m. Emporia American Legion Post


i

Dairy Day 2000

FOREWORD

Comparison of Heart of America Cowswith Kansas Cows - 1999

Item HOA KS

No. of herds

No. of cows/herd

Milk, lb

Fat, lb

Protein, lb

IOFC*, $

Milk price, $

1,184

170

19,035

693

621

1,651

13.98

362

101

19,476

704

633

1,559

13.74

*IOFC = income over feed costs

Members of the Dairy Commodity Group ofthe Department of Animal Sciences and Indus-try are pleased to present this Report of Prog-ress, 2000. Dairying continues to be a viablebusiness and contributes significantly to the totalagricultural economy of Kansas. Wide variationexists in the productivity per cow, as indicatedby the production testing program (Heart ofAmerica Dairy Herd Improvement Association[DHIA]). The Heart of America DHIA beganbusiness on January 1, 1995, by combiningthree labs into one. More than 137,000 cowswere enrolled in the DHI program from Kansas,Nebraska, Oklahoma, Arkansas, North Da-kota, and South Dakota beginning January 1,2000. A comparison of Kansas DHIA cowswith all those in the Heart of America DHIAprogram for 1999 is illustrated in the tableabove.

Most of this success occurs because ofbetter management of what is measured inmonthly DHI records. In addition, use of superi-or, proven sires in artificial insemination (AI)programs shows average predicted transmitting

ability (PTA) for milk of all Holstein AI bulls inservice (August, 2000) to be +1,390 lb. Con-tinued emphasis should be placed on furtheringthe DHI program and encouraging use of its re-cords in making management decisions.

The excellent functioning of the DairyTeaching and Research Center (DTRC) is dueto the special dedication of our staff. Appre-ciation is expressed to Richard K. Scoby,who recently retired after 13 years of dedi-cated service as manager of the DTRC.We acknowledge our current DTRC staff fortheir dedication: Michael V. Scheffel (Manager);Donald L. Thiemann; Daniel J. Umsheid; Wil-liam P. Jackson; Charlotte Boger; Lesa Reves;Eric Friedrichs; Robert Reves; and Greg Steer.Special thanks are given to Betty A. Hensleyand Cheryl K. Armendariz and a host of gradu-ate and undergraduate students for their techni-cal assistance in our laboratories and at theDTRC.

Each dollar spent for research yields a 30 to50% return in practical application. Research isnot only tedious and painstakingly slow butexpensive. Those interested in supporting dairyresearch are encouraged to consider participa-tion in the Livestock and Meat Industry Foun-dation (LMIF), a philanthropic organizationdedicated to furthering academic and researchpursuits by the Department of Animal Sciencesand Industry (more details about the LMIF arefound at the end of this publication).

J. S. Stevenson, Editor2000 Dairy Day Report of Progress


ii

Dairy Day 2000

CONTENTS

Dairy Day Program PageRaw Milk Quality: The Processor’s Point of View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Mastitis Management - Effective Methods to Reduce Somatic Cell Counts . . . . . . . . . . . . . . . . . . 4Silage Management: Important Practices Often Overlooked . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Manure ManagementManure and Lagoon Nutrients from Dairies Using Flush Systems . . . . . . . . . . . . . . . . . . . . . . . 13Flushing Sand-Laden Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

HealthSalmonella dublin: A Threat to Dairy Heifer Survival and Future Performance . . . . . . . . . . . . . . 21

Total Blood Protein as an Indicator of Colostral Sufficiency and Morbidity inDairy Calves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Antibiotic Versus Nonantibiotic Products for the Treatment of PapillomatousDigital Dermatitis (Hairy Heel Wart) in Dairy Cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Economics

Economics of Cooling Cows to Reduce Seasonal Variation in Peak Milk Production . . . . . . . . . . 29

NutritionMonensin: An Overview of Its Application in Lactating Dairy Cow Diets . . . . . . . . . . . . . . . . . . 33Effect of Level of Surface-Spoiled Silage on the Nutritive Value of Corn

Silage-Based Rations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Intake and Performance of Dairy Cows Fed Wet Corn Gluten Feed during the

Periparturient Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Determination of the Amount of Wet Corn Gluten Feed to Include in Diets for

Lactating Dairy Cows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Relationship among Concentrations of Milk Urea Nitrogen and Plasma Urea

Nitrogen and Feeding Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Facilities and Heat StressFactors Affecting Dry Matter Intake by Lactating Dairy Cows . . . . . . . . . . . . . . . . . . . . . . . . . 54Keeping Cows Cool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

ReproductionAnestrus in Lactating Dairy Cows before Ovulation Synchronization . . . . . . . . . . . . . . . . . . . . . 62Embryo Survival in Lactating Dairy Cows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Index of Key Words . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69Biological Variability and Chances of Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70The Livestock and Meat Industry Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71


1

Dairy Day 2000

RAW MILK QUALITY:THE PROCESSOR’S POINT OF VIEW

K. A. Schmidt

Summary

Raw milk quality is important to theprocessor for many reasons, this quality canbe assessed by several different tests. Qual-ity tests are used to ensure that the raw milkmeets legal USDA standards as well as someof the individual requirements of the proces-sor. Although some quality tests can be donein a matter of minutes, others require up toseveral days to complete. Because milkquality deteriorates relatively quickly, it isimportant to concentrate on those tests thatprovide the greatest amount of informationin the shortest time. This information then isextrapolated to assess the “actual raw milkquality”. After all, the quality of milk doesnot improve with time; thus, if the startingmaterials are substandard, the final productswill be less than substandard. Generally, rawmilk quality is assessed by type and numberof microbes, milk composition, presence ofcontaminants, and current (and perhapsprevious) temperature.

(Key Words: Raw Milk, Quality, IncomingTests.)

Microorganisms

In raw milk, the assumption is that patho-genic microbes (those that cause disease)will be present. However, in the U.S., mostprocessors do not assess the type and numberof a specific pathogen(s) in raw milk. Test-ing for specific microorganisms can be bothtime-consuming and inefficient. However,the type and number of microbes will affectthe quality of the product. Microbes differ intheir temperature and nutrient requirementsfor growth. For many years, lactic acidbacteria (LAB) were of great concern to

producers and processors. As LAB grow inmilk, they utilize lactose, subsequentlyproducing lactic acid, which causes a de-crease in pH. The milk then sours and as afinal result, it is unfit for fluid, cultured, orfermented products.

Over time, refrigeration has been man-dated at producer, in-transit, and processorlocations, because maintaining low tempera-tures (<45°F) minimizes the growth of LAB.Psychrotrophic bacteria, which can grow atlow temperatures, have become the predomi-nant microbes in raw milk today. Thesebacteria may not grow quickly at refrigera-tion temperatures, but they can utilize themilk components as nutrients and produceenzymes that further degrade fat, lactose, andproteins. Degradation of these milk compo-nents leads to off-flavors and odors that maycause the raw milk to be unfit for processingor consumption as fluid milk. Depending onthe reactions, this raw milk also may not besuitable for other dairy products. For in-stance, if the casein protein has been de-graded, cheese yields can be reduced drasti-cally and the off-flavors in the milk may becarried through to the final product. Inaddition, rancid or oxidized milk (the resultof fat degradation) is unsuitable for icecream or butter, because the fat-derived off-flavors carry through to the final product.Another issue is that as milk components aredegraded, their functionality changes and theability to manufacture some products may becompromised.

Pasteurization generally reduces the totalnumber of microbes in raw milk. A highernumber of bacteria implies that more reac-tions have occurred and more enzymes(which may not be inactivated during pas-


2

teurization) will be present in the pasteurizedmilk. This presence of more bacteria de-creases the shelf life of the product as well asits quality. Shelf life usually depends on thenumber of spoilage microorganisms presentin the milk. Once the number of bacteriareaches a certain level, the milk is considered“unsaleable”.

Typical microbial testing done at theprocessing plant on raw milk includescoliform, preliminary incubation (PI), andstandard plate count (SPC) tests. These threetests measure different aspects of the micro-bial quality and require 24 to 72 hr to per-form. The coliform test indicates the degreeof cleanliness of the raw milk. Greatercoliform counts are interpreted as potentialfecal contamination of the raw milk. Al-though no standard exists for maximumallowable coliform counts in raw milk, milkprocessors want raw milk with the lowestpossible number of coliforms. The SPCenumerates the number of aerobic bacteria inthe sample. Legally, maximum limits for thebacteria counts are allowed in fluid milk, andthese limits vary depending upon whetherthe milk is from a single source or is com-mingled. The PI testing is used as an indica-tion of the keeping quality of the milk.Often, individual plants set their own guide-lines and test conditions to define acceptablelimits for the PI test.

Composition

Legally, according to the PasteurizedMilk Ordinance, milk is defined by its fatand solids-not-fat contents. The public buysand consumes fluid milk (and other dairyproducts) based on fat content; thus, the fatand total solids contents of the incoming rawmilk play key roles in dairy foods marketing.

Milk fat imparts desired and uniquefunctionality to products such as milk, icecream, butter, and certain cheeses. Not onlyis the quantity of fat important for theseproducts, but the integrity of the fat (little tono chemical reactions such as oxidation orlipolysis) must be high, so that the finalproducts have acceptable flavors, odors, andtextures. Milk protein, in particular the

quantity and integrity of casein, influencescheese yields. Lactose contributes sweetnessand imparts viscosity to fluid milk and otherfluid dairy foods. Physically, lactose andminerals depress the freezing point of milk;thus, as their concentrations decrease, thefreezing point increases. Many processorsand governmental agencies use this relation-ship to determine if water has been added tothe raw or fluid milk product.

In most large plants today, thecompositional analyses can be done rela-tively quickly with the use of infrared tech-nology. This technology provides rapidresults for composition of protein, lactose,and total solids, depending on the sophistica-tion of the instrumentation. To determine ifwater was added to the milk, the freezingpoint is measured. This also is a rapid testthat is fairly accurate. Both types of instru-mentation can produce results within 5 to 10min depending on the instrumentation itself,operator experience, and calibration status.

Titrable acidity (TA) and pH are twoother chemical measurements that may beutilized to monitor the raw milk quality. Inboth cases, the acidity of the milk is mea-sured. Generally a “high acid” milk sampleindicates that microbial activity is high.These two methods measure different chemi-cal compounds within the milk, so theirinterpretations are different. Both methodsare easy and relatively inexpensive to per-form, provided the equipment is available.In the U.S., high-quality raw milk will fallwithin a narrow range of pH and TA levels.Thus, deviations from these narrow limitsindicate that raw milk quality has been com-promised.

Contaminants

In recent years, the main raw milk con-taminants of concern are antibiotics, toxins,and pesticide residues. All U.S. processorsmust test for the presence of antibiotic resi-due in raw milk prior to receiving the milkinto the plant. When antibiotic-contaminatedmilk is in the general milk supply, thoseindividuals who are allergic to a specificantibiotic may have an allergic reaction if


3

they consume the milk. To date, pasteuriza-tion does not inactivate antibiotics; thus, theypass from the raw milk into the final product.Over the years, reports of serious illness andseveral deaths have been associated withconsumption of milk that contained antibi-otic residues. Federal law mandates that allincoming raw milk is tested for the presenceof antibiotics. Most facilities have an ap-proved “quick” test procedure and equipmentfor detection of a certain type of antibiotics.These tests can take from 10 to 40 min de-pending on the equipment model andoperator’s experience.

Alfatoxin is a concern for all milk pro-cessors and producers. When a cow con-sumes tainted feed, aflatoxin may be trans-ferred into her milk. Aflatoxin is a powerfulneurotoxin that can harm humans. Recently,reports of other contaminants in dairy prod-ucts, such as dioxin, have surfaced. Resi-dues from pesticide and other treatmentsused for crop, land, or water managementcan be ingested by cows and eventually cantransfer into the milk. All of these unwantedcompounds can be dangerous for the con-suming public.

Most processing plants do not have thecapability to test for specific toxins in theraw milk supply. This testing may be doneat the main headquarters’ laboratory, or thedairy processing company may contract anoutside, independent, testing laboratory to dothese analyses. Testing for most contami-nants requires expensive equipment andtime-consuming procedures for the isolation,identification, and quantification of thespecific contaminant. In addition, test proce-

dures, equipment, and necessary reagentsdiffer depending on the specific toxin inquestion. Generally, this testing is not doneroutinely, but rather as an audit or if a load ofmilk is suspect.

Temperature

Temperature is critical, and most plantswill not accept a shipment of raw milk, if itexceeds a specific temperature. As tempera-tures increase, microbial growth increases.Microbial growth decreases the quality of themilk, as discussed above. Most plants relyon calibrated thermometers or temperature-sensing devices to verify raw milk tempera-ture. If raw milk temperature is above acritical level, usually 45°F as defined in thePasteurized Milk Ordinance, it will be re-jected. Generally, a lower limit is not set formilk temperature. However, a frozen load ofraw milk would be difficult to unload andprobably be unsuitable for processing.

Conclusions

All processors of raw milk are concernedabout the quality of the incoming product.They will use a variety of tests to assess thequality of the microbial activity; fat, protein,and total solids contents; presence of antibi-otics; and temperature to decide whether toaccept the load of milk. Processors continueto monitor the quality of the processed milkand relate it to the raw milk quality. It is notunusual for a processor to have set standardsfor the incoming ingredients as a means toensure the acceptability, quality, and safetyof the final product.


4

Dairy Day 2000

MASTITIS MANAGEMENT - EFFECTIVE METHODSTO REDUCE SOMATIC CELL COUNTS

M. J. Brouk and J. F. Smith

Summary

Mastitis is the most costly health concernin the dairy industry today. Annual losseshave been estimated at $180 to 185 per cow.Based on this figure, annual losses for Kan-sas producers may exceed $15 million.Nationally, mastitis may cost the industry$1.8 billion annually. Although treatmentand premature culling for clinical mastitisare costly, about two-thirds of the cost isassociated with reduced milk productioncaused by subclinical mastitis. Effectivemastitis control programs are necessary forthe dairy industry today. Prevention ofsubclinical mastitis is the key to lowering thesomatic cell counts (SCC). Elevated bulktank SCC (>250,000/ml) are an indicationthat a significant number of the cattle areinfected with mastitis-causing bacteria andcorrective action is required. Key areas toevaluate are cow housing, milking equip-ment, and milking procedures. Utilization ofmilk culture data is necessary to determineif elevated SCC are due to environmentalor contagious organisms. In addition, cul-tures of milk samples from individualcows may be needed to identify cattle in-fected with contagious organisms. Correc-tion of deficiencies in housing, milkingprocedures, and milking equipment willeffectively control environmental mastitis.Identification, segregation, and future cul-ling of animals infected with contagiousorganisms are necessary for control of conta-gious mastitis. An effective monitoringsystem that includes individual-cow SCC,individual-cow bacterial cultures, and bulk-tank bacterial cultures will ensure a lowbulk-tank SCC and a low level of mastitis.It is a health issue that requires constant

attention, because success is achieved withattention to detail on the dairy as a whole,and lack of attention in only one segment ofthe dairy may result in significant increasesin mastitis. Success of the program requiresthat all employees and the management team(managers, herdsmen, veterinarians, nutri-tionists, milking equipment technicians, andconsultants) emphasize increasing milkquality by controlling mastitis.. (Key Words: Mastitis, Milk Quality, Bacte-ria, Milk Production.)

Introduction

Mastitis is the number one health con-cern of the dairy industry today. It is notonly costly to producers at the farm level, butalso reduces the value of milk for the proces-sor and may impact the consumers’ accept-ability of dairy products. At the farm level,mastitis results in lower milk production,reduced milk quality, increased drug cost,increased culling, increased death losses, andincreased labor expense. Although produc-ers will focus on treatment of clinical masti-tis, it is most important to develop a mastitiscontrol program that will reduce not only thenumber of clinical cases, but also the numberof subclinical cases. The key to effectivemastitis control is prevention and a monitor-ing system that identifies problems early andcorrects them before a significant portion ofthe herd is infected. Effective mastitis con-trol involves defining the problem, develop-ing solutions, implementing of correctivemeasures, and utilizing a monitoring systemto identify future problems.


5

Defining the Problem

The first step in defining the problem isto admit that a mastitis problems exists in theherd. Many producers feel that they areproducing quality milk. However, when thesomatic cell counts (SCC) of bulk-tank milkare reviewed, counts that range from 400 to500 thousand/ml are not unusual. Is thisquality milk? That depends upon your defi-nition. The legal limit is 750 thousand/ ml,so the milk is under the legal limit. How-ever, some processors discount milk withthis level of SCC. Other countries alreadyhave reduced the lower limits to 500 thou-sand/ml, and the U.S. may need to adoptlower standards to open export markets invarious countries. Yes, the milk is legal, butwe can do better. Each producer should seta goal and work toward that goal. Manyprogressive dairy producers strive to holdbulk-tank SCC under 250 thousand/ml. Afew have lower goals.

Significant production increases areassociated with lower SCC. Table 1 outlinesthe expected losses in milk as SCC increasesfrom 50 thousand/ml. Cows in their secondor greater lactation are affected more thanfirst-lactation cows. Their lactation averageSCC of 400 thousand/ml is associated with aloss of 600 lb of milk, whereas the sameSCC level in older cows is associated with a1,200- lb loss. Currently, the average SCCof Kansas herds on DHI test exceeds 400thousand/ml. Based on this information,milk production on Kansas dairies is reducedby over 1,000 lb/cow/lactation. It is nowonder that states that lead in milk produc-tion/cow are also those that excel in milkquality as determined by SCC.

Producers should recognize that the mostcostly mastitis losses are due to subclinicalmastitis. Many times, producers are moreinterested in the latest treatment for clinicalmastitis, but subclinical cases are generallymore costly. Subclinical mastitis occurswhen no visible changes are detected in theudder, and the milk is free of visible abnor-malities. In such cases, the SCC will beelevated and the presence of bacteria may bedetected in cultures. These cows not only

increase the bulk-tank SCC, but serve as abacterial reservoir leading to the infection ofadditional cows.

Producers should strive to maintain abulk-tank SCC of <250 thousand/ml. Countsabove this level indicate a mastitis problem,and steps should be taken to identify theproblem and start corrective action. The firststep is to identify the types of organisms thatare contributing to the elevated SCC. Sam-ples of the bulk-tank milk should be culturedto identify whole-herd problems.

Samples should be taken from the bulktank on 5 consecutive days or from five milkpickups. They need to be taken from the topof the tank after the milk has been agitatedfor 15 min. Every effort must be made toprevent contamination of the sample duringthis process. Remember that bacteria areeverywhere in the environment. Hands,sampling tools, and nonsterile vials can serveas sources of contamination. In addition,sampling from the bottom of the tank canresult in contamination from the valve port.Use a clean dipper or sterile syringe to re-move a sample and transfer it to a sterilemilk sample vial. Filling the vial 50% full issufficient. Seal the vial with the cap andimmediately place it in a freezer. Freezingthe sample immediately stops bacterialgrowth and provides the laboratory with asample that accurately represents the truebacterial population of the bulk tank. Allow-ing the sample to set in a warm room evenfor a short period of time will allow bacteriato grow and increase in number. Becausedifferent bacteria grow at variable ratesunder similar conditions, allowing growth tooccur in the sample results in erroneousresults. Once all five samples are collectedand frozen, ship the samples to the labora-tory in an insulated container with frozen icepacks. It is important to ship the samples sothat they arrive at the laboratory frozen orcold. Thus, shipping method and day ofshipment should be discussed with the labo-ratory to ensure the that the samples arrive ingood condition and on a day of the week thatallows the laboratory to receive the samplesand begin the cultures.


6

The laboratory should return the resultsof the bulk-tank cultures in a few days. Theresults may be returned directly to the farmor the herd veterinarian. Table 2 is useful indeveloping the solution to the farm mastitisproblems.

Developing the Solution toMastitis Problems

Based on the bulk-tank cultures, severaldecisions can be made. First, is the problemenvironmental, contagious, or a combina-tion? As indicated in Table 2, environmentalproblems are best corrected with proper cowmanagement. Milking clean, dry udders andutilizing correctly adjusted equipment withproper milking procedures will reduce manyof the environmental pathogens and, thus,reduce environmental mastitis. The othermajor concern with environmental mastitis isthe housing area. Cows need a clean, dryresting area. Bacteria require nutrients,warmth, and a moist environment. Removalof any of the three reduces their growth.Correction of housing deficiencies and theutilization of dry cow treatments at dry-offprovides the best protection. Remember thatthe cow is most likely to develop a newmastitis infection in the first and last 2 wk ofthe dry period. Thus, the housing environ-ment during the dry period is critical toeffective mastitis-control programs.

If contagious organisms are found in thebulk-tank cultures, a different approach isneeded. Because contagious mastitis isspread at milking, it is important that theinfected cows be identified and segregated toprevent the spread of the organisms to addi-tional cows. The only way to identify theinfected cattle positively is throughindividual-cow milk cultures. This requiresthat a sample be taken from the cow utilizingsterile sampling techniques and submitted forbacterial evaluation. As with the bulk-tanksamples, it is very important that the samplenot be contaminated during the process.Bacteria are everywhere. They cling toudder hair, udder skin, milkers hands, andevery surface in the milking parlor. It isrecommended that gloves be worn and thatthe udder be clean and dry before sampling.

Samples should be taken prior to milking,and each teat end should be scrubbed withalcohol. Discard one squirt of milk prior tosampling and collect equal amounts fromeach teat if all quarters are being sampled.Filling the vial only 50% full is sufficient.Immediately freeze or place the vial on ice.Remember that bacterial grow well in warm,moist environments containing nutrients.Thus, warm milk is an excellent medium forbacterial growth. If the samples sit in thewarm milking parlor for several hours untilmilking is complete, erroneous results willoccur, and contagious animals may bemissed. It is generally unusual for a singlequarter to be infected with more than oneorganism. If results for individual cow milkcultures show two or more organisms, con-tamination likely has occurred.

Individual-cow milk samples are utilizedto identify the cows infected with contagiousmastitis. Once these cows are identified,they should be either culled or segregatedinto a separate group and milked last. Thecontagious pathogens are generally resistantto antibiotics. Thus, when a cow is infected,it likely will become a carrier. Separationfrom clean cows will minimize the risk toothers. Dry treatments also are usually noteffective on these organism, and if the cowremains on the farm for another lactation, itshould be considered infected with a conta-gious pathogen. Permanent visual identifica-tion may be helpful.

Implementation of the CorrectiveMeasures and Monitoring Systems

When problems have been identified anda control plan developed, it needs to beimplemented immediately. This requiresteam effort, and everyone must place priorityon the plan to ensure that it is implementedexactly. A monitoring system utilizingDHIA, bulk-tank SCC, bulk-tank cultures,and individual-cow milk samples atfreshening should ensure that problems aredetected early and corrected. Whenpurchasing cattle, milk samples from alllactating cows should be cultured before theyenter the herd. Samples from dry animalsshould be cultured upon freshening.


7

Allowing one contagious carrier to enter theherd could result in the culling of a highpercentage of the herd. Effective mastitis-control programs are not based on justcorrecting problems but on preventing

problems from occurring. This requiresconstant attention to detail on the dairy aswell as evaluation of culture data on acontinual basis.

Table 1. Estimated Differences in Lactation Milk Yield Associated with IncreasedSCC Score

Lactation Average Difference in Milk Yield1

Linear SCC Score SCC (1000s/ml) Lactation 1 Lactation $2

(lb/305 days)

0 12.5 --- ---

1 25 --- ---

2 50 --- ---

3 100 –200 –400

4 200 –400 –800

5 400 –600 –1,200

6 800 –800 –1,600

7 1,600 –1,000 –2,000

1Losses are relative to yields of cows with an SCC score of 2.Source: National Mastitis Council.


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Table 2. Interpreting Results of Bulk Tank Milk Cultures

Bacteria Type Source Suggested Control Procedures

Streptococcusagalactiae

Infected udders(contagious)

Use separate towels to wash and dry uddersUse postmilking teat dipDry treat all cows at dry-off

Staphylococcusaureus

Infected udders(contagious)

Use separate towels to wash and dry uddersUse postmilking teat dipDry treat all cows at dry-offCull chronically infected cowsMilk infected cows last

Mycoplasma species Infected udders(contagious)

Follow proper milking proceduresUse premilking teat disinfectionUse postmilking teat dipMilk infected cows lastCulture all replacement animalsCulture all cows and heifers at calvingCull infected cattle when possibleMaintain a closed herd

Non-agalactiaeStreptococcia

Environment Milk only clean, dry uddersImprove cleanliness of housingenvironmentUse premilking teat disinfectionUse postmilking teat dipDry treat all cows at dry-off

Coliforms Environment Milk only clean, dry uddersImprove cleanliness of housingenvironmentUse premilking teat disinfectionConsider vaccination program

Coagulase-negativeStaphylococci

Environment Keep udders cleanMilk only clean, dry uddersImprove cleanliness of housingenvironmentUse postmilking teat dipDry treat all cows at dry-off

Source: National Mastitis Council.


9

Dairy Day 2000

SILAGE MANAGEMENT: IMPORTANTPRACTICES OFTEN OVERLOOKED

K. K. Bolsen, B. E. Brent, M. K. Siefers,M. E. Uriarte, T. E. Schmidt, and R. V. Pope

Summary

Four important silage management prac-tices that are in the control of livestockproducers and that are sometimes poorlyimplemented or overlooked entirely include:inoculating, packing, sealing, and managingthe feedout face.

(Key Words: Silage, Silage Storage.)

Inoculating Silage Crops

Effective bacterial inoculants promote afaster and more efficient fermentation of theensiled crop, which increases both the quan-tity and quality of the silage. Inoculants haveinherent advantages over other addi-tives,including low cost, safety in handling, a lowapplication rate per ton of chopped forage,and no residues or environmental problems.The bacteria in commercial products includeone or more of the following species:Lactobacillus plantarum or otherLactobacillus species, various Pediococcusspecies, and Enterococcus faecium. Thesestrains of lactic acid bacteria (LAB) havebeen isolated from silage crops or silages andwere selected because: 1) they are homo-fermentative (i.e., ferment sugars predomi-nantly to lactic acid), and 2) they grow rap-idly under a wide range of temperature andmoisture conditions. Recently, several prod-ucts also have contained Lactobacillusbuchneri (a heterofermentative LAB) orstrains of Propionibacterium (which arecapable of producing propionic acid duringthe ensiling process).

Inoculant research at Kansas StateUniversity. Evaluation of silage additivesbegan in 1975 in the Department of Animal

Sciences and Industry. A summary of resultsfrom over 200 laboratory-scale studies,which involved nearly 1,000 silages and25,000 silos, indicated that bacterial inocu-lants were beneficial in over 90% of thecomparisons. Inoculated silages have fasterand more efficient fermentations –– pH islower, particularly during the first 2 to 4 daysof the ensiling process for hay crop forages,and lactic acid content and the lactic to aceticacid ratio are higher than in untreated si-lages. Inoculated silages also have lowerethanol and ammonia-nitrogen values com-pared to untreated silages.

Economics of bacterial inoculants.What is the “bottom line” calculation of thevalue of inoculating corn silage and alfalfahaylage for a dairy herd with an averagemilk production of 87 lbs per cow per dayand a daily dry matter (DM) intake of 54.2lbs? The increase in net income, calculatedon a per ton of crop ensiled or per cow perday or per cow per year basis, is realizedfrom increases in both preservation and feedutilization. The additional "cow days" perton of crop ensiled, because of the increasedDM recovery, and the increased milk percow per day from the inoculated silage orhaylage (0.25 lbs) result in a $6 to $7 in-crease in net return per ton of corn ensiledand about a $14 to $15 increase in net returnper ton of alfalfa ensiled.

Recommendations . Why leave thecritical fermentation phase to chance byassuming that the epiphytic microorganisms(those occurring naturally on the forage) are going to be effective in preserving thesilage crop? Even if a dairy or beef cattleproducer's silage has been acceptable in thepast -- because silage-making conditions in


10

most regions of North America are gener-ally good -- there are always opportunitiesfor improvement.

Although whole-plant corn and sorghumensile easily, research data clearly show thatthe quality of the fermentation and subse-quent preservation and utilization efficien-cies are improved with bacterial inoculants.Alfalfa (and other legumes) are usuallydifficult to ensile because of a low sugarcontent and high buffering capacity. How-ever, adding an inoculant helps ensure that asmuch of the available substrate as possible isconverted to lactic acid, which removessome of the risk of having a poorly pre-served, low-quality silage. Finally, if produc-ers already are doing a good job but using abacterial inoculant for the first time, theyprobably will not see a dramatic difference intheir silage. But the benefit will be there ––additional silage DM recovery and signifi-cantly more beef or milk production per tonof crop ensiled.

Selecting a bacterial inoculant. Theinoculant should provide at least 100,000 andpreferably 200,000 colony-forming units ofviable LAB per gram of forage. These LABshould dominate the fermentation; producelactic acid as the sole end product; be able togrow over a wide range of pH, temperature,and moisture conditions; and ferment a widerange of plant sugars. Purchase an inoculantfrom a reputable company that can providequality control assurances along with inde-pendent research supporting the product'seffectiveness.

Achieving a Higher Silage Density

Achieving a high density of the ensiledforage in a silo is an important goal for dairyproducers. First, density and crop DM con-tent determine the porosity of the silage,which affects the rate at which air can enterthe silage mass at the feedout face. Second,the higher the density, the greater the capac-ity of the silo. Thus, higher densities typi-cally reduce the annual storage cost per tonof crop by both increasing the amount ofcrop entering the silo and reducing croplosses during storage. Recommendations

usually have been to spread the choppedforage in thin layers and pack continuouslywith heavy, single-wheeled tractors. But thefactors that affect silage density in a bunker,trench, or drive-over pile silo are not com-pletely understood. Kurt Ruppel (Pioneer Hi-Bred) measured the DM losses in alfalfasilage in bunker silos and developed anequation to relate these losses to the densityof the ensiled forage (Table 1). He found thattractor weight and packing time per ton wereimportant factors; however, the variability indensity suggested other important factorsthat were not considered.

In a recent study, Brian Holmes, exten-sion specialist at the University ofWisconsin-Madison, and Rich Muck, agri-cultural engineer at the U.S. Dairy ForageResearch Center in Madison, measuredsilage densities over a wide range of bunkersilos in Wisconsin, and the densities werecorrelated with crop/forage characteristicsand harvesting and filling practices. Sampleswere collected from 168 bunker silos, and aquestionnaire was completed about how eachbunker was filled. Four core samples weretaken from each bunker feedout face, andcore depth, height of the core hole above thefloor, and height of silage above the corehole were recorded. Density and particle sizealso were measured.

The ranges of DM contents, densities,and average particle size observed in the haycrop and corn silages are shown in Table 2.As expected, the range in DM content wasnarrower for the corn silages compared to thehay crop silages. The average DM content ofthe corn silages was in the recommendedrange of 30-35%. But several of the haylageswere too wet (less than 30% DM), which canlead to effluent loss and a clostridial fermen-tation, or too dry (more than 45% DM),which can lead to extensive heat damage,mold, and the risk of a fire. The average DMdensities for the hay crop and corn silageswere similar and slightly higher than a com-monly recommended minimum DM densityof 14.0 lb/cu ft. Some producers wereachieving very high DM densities, whereasothers were severely underpacking. One verypractical issue was packing time relative to


11

the chopped forage delivery rate to thebunker. Packing time per ton was highest (1to 4 min/ton on a fresh basis) under lowdelivery rates (less than 30 tons/hr on a freshbasis). Packing times were consistently lessthan 1 min/ton (on a fresh basis) at deliveryrates above 60 tons/hour.

Dairy producers can control several keyfactors to achieve higher densities, whichwill minimize DM and nutrient losses duringensiling, storage, and feedout.

Forage delivery rate. Reducing thedelivery rate is somewhat difficult to accom-plish, because very few dairy producers orsilage contractors are inclined to slow theharvest rate so that additional packing can beaccomplished.

Packing tractor weight. This can beincreased by adding weight to the front ofthe tractor or 3-point hitch and filling thetires with water.

Number of tractors . Adding a second orthird packing tractor as delivery rateincreases can help keep packing time in theoptimum range of 1 to 3 minutes per ton offresh forage.

Forage layer thickness. Chopped for-age should be spread in thin layers (6 to 12inches). In a properly packed bunker silo, thetires of the packing tractor should pass overthe entire surface before the next forage layeris distributed.

Filling the silo to a greater depth.Greater silage depth increases density. Butthere are practical limits to the final foragedepth in a bunker, trench, or drive-over pile.Safety of employees who operate packingtractors and who unload silage at the feedoutface becomes a concern. Packing in bunkersthat are filled beyond their capacity and thechance of an “avalanche” of silage from thefeedout face pose serious risks.

Table 1. Dry Matter Loss as Influencedby Silage Density

Density(lb of DM/ft3)

DM Loss at 180 Days (% of the DM ensiled)

10 20.2

14 16.8

16 15.1

18 13.422 10.0

Table 2. Summary of Core Sample Analysis from the Bunker Silos

Silage CharacteristicHay Crop Silage (87 Corn Silage (81 silos)

Avg Range Avg Range

Dry matter, % 42 24-67 34 25-46

Density on a fresh basis, lb/cu ft 37 13-61 43 23-60

Density on a DM basis, lb/cu ft 14.8 6.6-27.1 14.5 7.8-23.6


12

Protecting Silage from Air and Water

Until recently, most large bunker, trench,or drive-over pile silos in Kansas were leftunsealed. Why? Because producers viewedcovering silos with plastic and tires to beawkward, cumbersome, and labor-intensive.Many believed the silage saved was notworth the time and effort required. But ifsilos are left unprotected, DM losses in thetop 1 to 3 ft can exceed 60 to 70%. This isparticularly disturbing when one considersthat in the typical “horizontal" silo, 15 to25% of the silage might be within the top 3feet. When the silo is opened, the spoilage isapparent only in the top 6 to 12 inches ofsilage, obscuring the fact that this area ofspoiled silage represents substantially moresilage than originally stored.

The most common sealing method is toplace polyethylene sheet (6 mil) over theensiled forage and weight it down withdiscarded tires (approximately 20 to 25 tiresper 100 sq ft of surface area). Producers whodo not seal need to take a second look at theeconomics of this highly troublesome “tech-nology”, before they reject it as unnecessary

and uneconomical. The loss from a 40 × 100foot silo filled with corn silage can exceed$2,000. Loss from a 100 × 250 foot silo canexceed $10,000.

Managing the Feedout Face

The silage feedout "face" should bemaintained as a smooth surface that is per-pendicular to the floor and sides in bunker,trench, and drive-over pile silos. This willminimize the square feet of surface that areexposed to air. The rate of feedout throughthe silage mass must be sufficient to preventthe exposed silage from heating and spoiling.An average removal rate of 6 to 12 inchesfrom the “face” per day is a common recom-mendation. However, during periods ofwarm, humid weather, a removal rate of 18inches or more might be required to preventaerobic spoilage, particularly for corn, sor-ghum, and whole-plant wheat silages.

For more information about these andother silage management practices visit theKansas State University Silage Team’swebsite at:

http://www.oznet.ksu.edu/pr_silage.


1Department of Biological and Agricultural Engineering.2Nemaha County Extension Agent.

13

Dairy Day 2000

MANURE AND LAGOON NUTRIENTS FROMDAIRIES USING FLUSH SYSTEMS

T. D. Strahm1, J. P. Harner 1,D. V. Key 2, and J. P. Murphy 1

Summary

Nine primar,y lagoons and solids storagebasins were sampled on Kansas dairies usingflush systems. These samples were analyzedfor nutrient content of wastewater and sandmanure. The manure moisture content in thestorage basins averaged 81%. The averagetotals of nitrogen, phosphate, and potashwere 3450, 1345, and 1420 mg/L, respec-tively, for flushing systems. The averagetotals of nitrogen, phosphate, and potash inthe lagoon samples were 816, 337, and 1134mg/L, respectively, for dairies using recycledwater for flushing alleys. These data andpreviously reported data indicate that lagooneffluent and manure removed from basinsmust be managed differently between dairiesusing flush versus scrape systems.

(Key Words: Manure, Nutrients, Dairy,Sand, Lagoons.)

Introduction

Consulting engineers and extensioneducators can use the MidWest Plan Service(MWPS) MWPS-18 Handbook, NaturalResource Conservation Service (NRCS)National Engineering Handbook 651, orASAE Standard D384.1 Manure Productionand Characteristics for information on theexpected daily nutrient production per givenanimal unit. Most of these data are based onexcreted manure rather than manure thatactually is being applied to the land. As-sumptions as to the expected losses andlocation, i.e., lagoon or solids storage basin,

of the nutrients must be made based on theengineer’s experience.

Many dairies are using total mixed ra-tions and sand- or manure-bedded freestalls. However, limited information is availableon the nutrient content of waste streams fromthese freestalls. The purpose of this studywas to characterize the manure and effluentnutrients from dairies using recycled waterfor flushing their facilities.

Procedures

Samples were collected from manurestorage basins at nine Kansas dairies. Thedairies used sand bedding or compostedmanure in the stalls. The dairies used flushsystems to clean freestall housing and hold-ing pen areas. The sampling was completedduring spring 2000.

Manure samples were retrieved using acapped PVC cylinder attached to a metalelectrical conduit handle on five of the dair-ies. A cord was connected to open a spring-closed lid, while the cylinder was under thesurface. Depending on the amount of ma-nure in the basin, samples were taken atdepths of 2 to 3 ft. The sampler was used toopen the crust and then was pushed to thedesired depth before the lid was pulled opento collect the sample. Four to six individualsamples were taken from around the perime-ter (3 to 4 ft from the edge) of each basin andthen mixed in a bucket to make one compos-ite sample. On two dairies, solid manure


14

samples were taken from mechanical solidseparators.

Some of the lagoon samples were col-lected with the same sampling device. Othersamples were collected with a PVC samplerthat was thrown 40 to 50 ft from the edgeinto the water. The sampler was weightedand filled as it sank below the sur-face. Theindividual samples were combined and ana-lyzed as one composite sample. The sampleswere refrigerated in 1 liter plastic bottlesuntil sent for laboratory analysis. Servi-TechLaboratories completed total nutrient analy-sis on each sample. Samples also werecollected at several dairies using 30 pansplaced in a field prior to land application oflagoon effluent using reel irrigation systems.These samples were taken to evaluate thevariability in sprayed effluent.

Results and Discussion

Data in Table 1 show the average nutrientanalysis of the manure samples taken fromthe solids basins. Manure samples from thetwo dairies that used mechanical solid separ-ators had an ash content of about 2%. Sam-ples from the other dairies had ash contentsranging from 4 to 13%. The electrical con-ductivity and pH averaged 7.5 mmho/cm and6.4, respectively. The average total nitrogenwas 3,420 mg/L of which 94% was in theorganic form. The phosphate and potassiumaveraged 1345 and 1420 mg/L, respectively.

Table 2 shows the nutrients availablefrom the lagoons on dairies using a flushsystem. The average total nitrogen (TN) was816 mg/L, about five times higher thanaverage values for the scrape systems. Ap-proximately 50% of the N was in the ammo-nia form, and the remainder as organic N.Phosphate averaged 337 mg/L, which is 4.5times more than the average for the scrapesystems, and potash was more than double at1134 mg/L.

The data in Table 3 for TN indicate thatdifferent management strategies are neededwhen pumping effluent from lagoons locatedon dairies using scrape and flush systems.The nutrient values for dairies using a scrap-

ing system were reported in 1999 DairyDays. If effluent is pumped annually ontofields adjacent to a lagoon and TN rates arelimited to 114 kg (250 lb) per acre, then only2 inches of water from the lagoon storing therecycled flush water could be applied peracre. About 7 inches of water could beapplied to land receiving lagoon effluentfrom a dairy using a scrape system. Withthese application rates, excessive phosphatesshould not be applied to cropland.

Table 4 shows nutrient concentrationsand properties of samples taken from flushsystems with composted manure or sandbedding. Nutrient concentrations were great-er in the solid and liquid samples from facili-ties using composted manure, especiallyphosphorus. The liquid samples from com-posted manure bedding had greater concen-trations of total dissolved solids, 5830 mg/Las compared to 3940 mg/L from sand bed-ding. Similarly, the solid manure samplesfrom sand-bedded facilities contained lessorganic matter and more ash.

The following are initial conclusionsderived from this field study:

1. The ratio of total nitrogen to phosphoruswas approximately 3 in manure fromdairy cows fed total mixed rations usinga corn silage-based ration.

2. The moisture content of manure was81% for dairies using flush systems withconcrete basins, earthen basins, or me-chanical separators.

3. Nutrient content in lagoons from dairiesusing recycled flush water was muchhigher than that found in lagoons ondairies that are scraping.

4. A comparison of flush systems showedgreater nutrient concentrations whencomposted manure was used as beddingthan when sand was used.

5. Additional data are needed from moredairies using recycled flush water toquantify the nutrients available fromlagoons and storage basins.


15

Acknowledgment

The authors thank the dairy producerswho cooperated with this study and allowedthem access to their dairies.

Table 1. Nutrient Analysis of Manure Samples Taken from Storage Basins on DairiesUsing a Recycled Flush System

Nutrient Units Average S.D.Organic nitrogen mg/L 3251 768Urea mg/L 182 193Nitrate - nitrogen mg/L 17.1 28.3Total nitrogen mg/L 3450 805Phosphorus (P2O5) mg/L 1345 643Potassium (K2O) mg/L 1420 680Other Properties: Moisture % 80.7 4.2 Solids % 19.3 4.2 Organic matter % 12.6 4.9 Ash % 6.7 4.1 Carbon/nitrogen ratio 23.0 10.9Electrical conductivity mmho/cm 7.5 4.5pH 6.4 0.8Total salts mg/l 11786 5969

Table 2. Nutrient Analysis of Manure Samples Taken from Primary Lagoons on DairiesUsing a Recycled Flush System

Nutrient Units Average S.D.Organic nitrogen mg/L 418 150Ammonia mg/L 398 176Nitrate-nitrogen* mg/L 1.1 0.2Total Kjeldahl nitrogen mg/L 816 266Phosphorus (P2O5) mg/L 337 173Potassium (K2O) mg/L 1134 367Other Properties: Chloride mg/L 377 245 Total dissolved solids mg/L 4753 1299 Water pH 7.7 0.2 Electrical conductivity mmho/cm 7.9 1.6 Sodium adsorp. ratio (SAR) 3.0 1.3

*1.0 mg/l = 1 or less.


16

Table 3. Comparison of Average Nutrient Values for Samples Taken from Storage Basinsand Lagoons on Dairies Using Scrape and Flush Systems for Handling Manure

Concrete Basins

Handling System

Nutrient Units Scrape Flush

Organic nitrogen mg/L 3489 3251Urea mg/L 1700 182Nitrate-nitrogen mg/L 3.2 17.1Total nitrogen mg/L 5191 3450Phosphorus (P2O5) mg/L 2539 1345Potassium (K2O) mg/L 4157 1420

Lagoons

Handling System

Nutrient Units Scrape Flush

Organic nitrogen mg/L 80 418Ammonia mg/L 77 398Nitrate-nitrogen mg/L 0.3 1.0Total Kjeldahl nitrogen mg/L 156 816Phosphorus (P2O5) mg/L 74 337Potassium (K2O) mg/L 512 1134

Table 4. Comparison of Average Sample Characteristics with Composted Manure andSand Bedding in Flush Systems

Solid Liquid

Nutrient Units Sand Manure Sand Manure

Total nitrogen mg/L 3100 3920 760 900

Phosphorus (P2O5) mg/L 1300 1410 300 380

Potassium (K2O) mg/L 1260 1630 930 1410

Other Properties:

Total dissolved solids mg/L 3940 5830

Moisture content % 81.4 79.8

Organic matter % 11.3 14.3

Ash % 9.0 6.0


1Department of Biological and Agricultural Engineering.

17

Dairy Day 2000

FLUSHING SAND-LADEN MANURE

J. P. Harner 1, T. D. Strahm1, and J. P. Murphy 1

Summary

Sand can be handled successfully either ina scrape or flush system by developing han-dling systems that allow for the sand-ladenmanure to settle prior to the effluent enteringa lagoon. The abrasiveness and density ofsand create problems in handling the ma-nure. Manure weighs about 60 lb/cu ft,whereas sand has a density of 120 lb/cu ft.Sand-laden manure will have an approximatedensity of 80 lb/cu ft, if 30% of the manureis sand. Because sand is heavier, it will notremain in suspension as long as manure andsettles rapidly. Many problems associatedwith handling sand-laden manure can beavoided if the solids are stored separatelyfrom the effluent.

(Key Words: Flush, Sand, Manure, Bedding.)

Review of Flushing Sand-Laden Manure

Flushing dairy manure is an alternative toblade scraping of freestalls or holding pens.Advantages include labor reduction withautomated systems, limited scraping require-ments, lower operating cost, drier floors,potential reduction in odor, and cleanerfacilities. An optional method of handlingmanure may be necessary in colder weather.Flushing does not eliminate the need to applythe manure and effluent to land at environ-mentally acceptable levels.

Daily water requirements for flushingvary depending on the width, length, andslope of the alley and bedding material. With

organic bedding at a slope of 3%, a mini-mum flush volume is 100 gal/ft of gutterwidth for flushing lengths of less than 150 ft.Longer lengths require more water with asuggested maximum release of 175 gal/ft ofgutter width. A study of six dairies foundflush water requirements ranging from 240 to620 gal/cow/day. Another procedure sug-gests selecting the larger of two volumes —either 52 gal/cow/flush or 1.35 gal/sq ft ofalley/ flush. Observations with sand-ladenmanure (SLM) suggest that a high-velocityflush system can clean alleys with less withthan 1 gal/sq ft, whereas low-velocity systemmay require more than 4 gal/sq ft.

The cleanliness of an alley depends on theenergy of flush water to remove the SLM.Design practices suggest that the flushingwave needs to be 150 ft in length, 3 inchesdeep, and moving at a velocity of 5 ft/sec.Buildings longer than 450 ft require the flushwave to be at least 1/3 of the total length. Ifthe length is less than 150 ft, then the designprocedure is based on a 10 sec contact time.The amount of time flush water moves pasta given selection of the alley is known ascontact time. However, based on observedprocedures, contact times of 10 min or longeroften are used in flushing alleys, if thevelocity is less than 3 ft/sec. These dairiesare using longer flush times in an attempt toavoid scraping alleys.

The two basic flush mechanisms are high-and low-velocity systems. For purposes ofthis paper, a high-velocity flush system useswave velocities greater than 5 ft/sec with 7.5ft/sec being preferred. Low-velocity flush


18

systems have wave velocities of less than 5ft/sec, generally around 3 ft/sec.

Storage structures often are used for high-velocity flush systems, and pumps generallyare used for low-velocity flush systems. Atank or tower at the upper end of the areabeing flushed is used to store the flush water.Flushing tanks with 4 to 12 ft depth havelarge discharge openings. Towers havedepths of 20 ft or more and dischargethrough 12- to 24-in-diameter pipe. A lowhorsepower pump is used to transfer waterfrom the lagoon to the storage tank.Flushing-pump systems utilize the lagoon forstoring the flush water. A large horsepowerpump then pumps the water to the upper endwhen flushing is desired. Storage towersmay be used with low-velocity flush sys-tems, but piping losses reduce the flow ve-locity.

The release rate varies from a minimumof 10 sec to more than 60 sec for longerbuildings with high-velocity flush systems.Release rates can vary from 1,000 gal/min toover 15,000 gal/min, if the system is de-signed properly. Flush water pumping orlow velocity flush systems often are limitedby the pump capacity, and the water-releaserate is 60 sec or longer. Most of the pump-ing systems are limited to a release rate ofless than 3,000 gal/min.

A simple high-velocity flush systemconsists of tanks that are 9 to 10 ft in diame-ter and 25 ft or taller. The flushing systemmay use a 6- to 7-ft section of 16-inch pipeexiting the tank at a right angle. This pipehas a 45° slope inlet inside the tank. Another6- to 7-ft section of 12-inch pipe, whichincludes a 12-inch manual gate valve, then isused to carry the water to the flush alleys.The pipe outlet directs the water along thefreestall curb. One field study found thatflush velocity decreased from 11.5 ft/sec to6.7 ft/sec as the head decreased from over 30ft to less than 10 ft. Based on the number offreestalls and flushing three times per day,the water usage was 48 gal/stall/flush or 140gal/day/stall. The water usage based on a8,500 gal/min discharge rate and a 30-secflush was equal to 0.84 gal/sq ft, giving a

flow rate of 700 gal/min and a water usage of350 gal/ft width of gutter.

Field flush velocities were obtained fromfour barns using concrete tanks with manualguillotine or scissor-gate flush system. Twoof the barns released the flush at a 90° angleto the alleys. The release was parallel to thelong axis of the alleys in the other barns.The tanks were commonly 4 ft deep withlength and width dimensions of 12 ft by 16ft. The flush water exited the tank throughan orifice measuring 8 inches by 96 inches atfull opening. The flush velocities in theguillotine tanks were 6 to 9 ft/sec. The tankswith the flush water exiting at a right angleto the alley had a flush velocity 2 ft/secslower than the other tanks.

Some scraping or manual cleaning alongthe freestall curb may be needed, becausemuch of the manure is deposited here. A0.75- to 1-inch crown in the alley is neededto direct more flush water along the curbs, iffreestalls are along both sides. The crownwill interfere with scraping. Recently, alleyshave been sloped 0.5 to 1 inch from theoutside to the freestall curb to increase thedepth of the flush wave along the curb withhead-to-head freestalls.

Flush water commonly is released using"pop-up" or recessed valves controlled man-ually or automatically. Automated valvesare operated pneumatically. Discharge ratefrom a valve is influenced by the hydrauliccharacteristics of the pipeline to the valve.Common design procedures connect multipletanks to a valve from both sides to maintaina higher head pressure and, thus, increase thedischarge rate. Other release methods in-clude a hinged plate, open pipe, and gatedpipe.

Flush water is collected at the lower endof a building in a gutter alley or basin. Thewater flows towards a mechanical separatoror gravity-settling basin. The separationallows the solids to accumulate in a basinand the liquid to drain to a lagoon.

Dairies using sand-bedded freestalls needto have a sand trap or sand separator located


19

ahead of the mechanical solids separator.The abrasive action of sand in the pumps andon screens in mechanical solid separatorsdecrease equipment life and increases main-tenance cost.

The mechanical separator may be aninclined screen, press roller, or screw press.The inclined screen allows the liquid to passthrough the screen, and the solids remainingon the surface are transferred to a storagearea. In the press roller, the flushed materialpasses through a pair of rollers and the waterdrains away. The screw press uses morepressure to separate liquids and solids. Grav-ity type systems use a settling basin to settleout the solids and drain off the liquids.

Based on visual inspection of alleys withsand bedded freestalls, the minimum flushvelocity should be 5 ft/sec with 7.5 ft/secbeing preferred. Current guidelines on re-lease rates with 400-ft alleys seem to beadequate. The water depth at the freestallcurb should be a minimum of 3 inches with4 inches preferred. The energy of the flushwater needs to be directed along the freestallcurb rather than in the center of the alley.

Gravity and mechanical separations aretwo basic methods for settling out the sandfrom the manure stream prior to solids sepa-ration. Gravity basins depend on the abilityof the system to slow the flush velocity to 1to 2 ft/sec. At these velocities, the organicmatter appears to remain suspended with theliquid and will discharge from the sand trapwith minimal settling. Field data show thatless than 3% of the solid material in the sandtrap is organic material. The sand can berecovered from a solids-separating basin,because much of it settles out near the dis-charge pipe when a flush system is used.Generally the sand is stacked and dried priorto its reuse.

A mechanical separator has been devel-oped that has the ability to recycle 90% ormore of the sand from the waste stream. Thesand is much cleaner than that from a gravityseparator, because it is washed. The me-chanical separator works better with coarsesand than fine sand. Studies have shown that

inclined screens are not effective in separat-ing sand from the waste stream. The screenopenings are larger than the sand particles.Sand also had a tendency to settle out up-stream of the inclined separator as the flushwave velocity is reduced.

Here are some general guidelines toremember when working with sand:

1. Sand-laden manure will not stack or pilelike manure mixed with organic material.It tends to spread and move away, partic-ularly in wet weather.

2. The longer sand-laden manure is in stor-age, the easier it is to handle. A mini-mum storage of 45 days is recommended.

3. It is easier to handle sand-laden manurecontained in a structure other than thelagoon or holding pond.

4. Begin the waste-handling system designby taking advantage of gravity. Usepumps and augers as a last resort in mov-ing the manure stream.

5. Generally, the top surface will be a slurry,and initial emptying of a solids-storagebasin takes time. Once the slurry is re-moved (for small dairies, this representsabout 10%), the rest of the material in thestructure will be at less than 80% mois-ture.

6. Flushing systems work better when theenergy created by the water depth or headpressure in the flush water tower (andpumps) is used to move manure and sandrather than flush water through the pipesand elbows. A certain amount of energyis lost for every foot of pipe the flushwater must move through. When flush-ing sand, it is better to purchase morestorage towers and move them closer tothe alleys than to buy pipes and elbows. Ifthe piping system is desired, then use alarger pipe for the manifold system anddo not reduce down to the pop-up valvesize until after the last elbow or tee joint.


20

7. Some producers are experimenting withstockpiling gravity-separated sand. Mostare partially blending the dirty sand withclean sand. The stockpiling period rangesfrom 1 to 6 mo prior to reuse. The runofffrom the sand pile should be containedand transferred to the lagoon. In a recy-cled flush water system, the additionaldrainage area may be beneficial in pro-viding some extra flush water.

Summary

Flushing can be a viable alternative toscraping of dairy manure. Facilities can be

constructed for the addition of flushingsystems at a later date, even if scraping isplanned in the immediate future. This re-quires placing the buildings at arecommended 2% slope. A 6 to 8 ft differ-ence in elevation between the lower end ofthe flushed areas and the lagoon freeboardwill be necessary for inclusion of separationequipment and transfer collection gutters.Inclusion of flushing systems in existingbuildings must be determined on an individ-ual basis. An adequate supply of fresh waterfor flushing the milk parlor and holding penalso must be available.


1Food Animal Health and Management Center.

21

Dairy Day 2000

SALMONELLA DUBLIN: A THREAT TO DAIRY HEIFER SURVIVAL AND FUTURE PERFORMANCE

D. G. Schmidt, D. P. Gnad,J. M. Sargeant 1, and J. E. Shirley

Summary

Salmonella dublin is a bacterium that canhave devastating effects in dairy herds. It ismost deadly with calves that range in agefrom 10 days to 5 months. Salmonella dub-lin is shed from carrier animals throughfeces, milk, and colostrum and spread by oralingestion. Clinical signs are not detectedeasily until after the infection is well estab-lished. Calves may suffer from septicemia,diarrhea, fatigue, and unthriftiness. Death isnot an uncommon outcome of this disease.Clinical signs of infection in adults mayrange from none to enteritis or abortion.Combating the disease requires an awarenessof the disease, a preventive herd health pro-gram, and attention to detail in caring for thenewborn calf.

(Key Words: Salmonella dublin, Heifers,Calves.)

Introduction

Salmonella is an invasive pathogen thatmust be taken seriously in today's dairyindustry. Salmonella dublin and S.typhimurium are the strains most frequentlyisolated from cattle. Salmonella dublin is thetopic of concern in this report. In calves, thebacterium cause septicemia with high ratesof morbidity and mortality. Clinical signs areless severe in adult cows.

Many producers purchase outside re-placement heifers or utilize outside growers,placing them at risk of exposing their herd toS. dublin-infected animals. Calves that are

exposed to carriers of S. dublin are at a highrisk of developing clinical salmonellosisand/or becoming carriers themselves. Themost common route of transfer to uninfectedanimals is S. dublin shed by carrier animalsin feces, colostrum, or milk. Only one carrierof S. dublin is needed to infect an entire herd.Good biosecurity practices are essential toprevent the entry and control the spread of S.dublin in dairy herds. This article reviewsrecent research concerning the effects of S.dublin on the survival rate and subsequentperformance of dairy heifers.

Review of Research

An important step in raising replacementheifers is to ensure that newborn calvesreceive adequate amounts of qualitycolostrum shortly after birth. It is critical thatthis colostrum be from cows that are notcarriers of S. dublin, because the bacteriamay be ingested by the neonatal calf. Re-search indicates that during the time justbefore parturition, shedding of S. dublin fromthe cow increases; thus increasing the likeli-hood of it passing into the colostrum and intothe calf.

Young calves are more susceptible to S.dublin than older calves and adults. This ispartially due to higher pH (5.2) in theirabomasum. The abomasal pH levels of 4.8or less commonly found in older calves andadults are detrimental to viability of S. dub-lin. Ruminal contents from calves that are>6 wk of age also have been shown to in-hibit S. dublin.


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Calves infected with S. dublin do notshow specific clinical signs of infection untilthe disease is well established. Pneumonia,septicemia, diarrhea, unthriftiness, and deathcommonly are seen with S. dublin infection.As the infection progresses, strands of intes-tinal mucosa and blood may be found in thefeces. The loss of intestinal mucosa reducesthe calf’s ability to absorb nutrients andcombat other infections that challenge theintestinal lining. Cattle that recover from anacute infection of S. dublin may shed thepathogen for 4 to 6 wk afterwards. A smallnumber of animals may recover clinically,but remain carriers of the bacteria. Manycalves that are infected with the pathogenand recover never reach their full perfor-mance potential.

Fecal culture commonly is used to diag-nose S. dublin infections in cattle, but falsenegatives are common because of intermit-tent fecal shedding. Submitting multiplefecal samples from a single animal can mini-mize false negatives. However, because ofcost of fecal culture and the intermittent fecalshedding by the cow, this test is not practicalfor herd monitoring.

Studies also show that S. dublin cansurvive up to 30 mo in dried feces, 120 daysin pasture soil, 115 days in pond water, and87 days in tap water. Therefore, good ma-nure management must be practiced on theentire farm. Good manure hygiene practicesare critical in maternity and calf rearingareas. Maternity pens should be cleanedroutinely, and calves should be removedfrom calving areas as soon as possible andplaced in clean areas free from adult manure.Calves should be fed an adequate amount ofquality colostrum obtained from a S. dublin-free dam. Pooling colostrum from multiplecows increases the chances for calves to beexposed to S. dublin. Minimizing calf-to-calf contact from the minute the calf is bornuntil weaning also is important in preventingthe spread of disease.

Along with good management practices,vaccination against S. dublin can be used toprotect neonatal calves from infection.However, vaccination alone, without goodbiosecurity measures, is not sufficient toprevent and control S. dublin infection.Preventing and controlling S. dublin in dairyherds can be accomplished only with a multi-dimensional approach.


1Food Animal Health and Management Center.

23

Dairy Day 2000

TOTAL BLOOD PROTEIN AS AN INDICATOR OF COLOSTRAL SUFFICIENCY AND MORBIDITY IN DAIRY CALVES

D. G. Schmidt, D. P. Gnad,J. M. Sargeant 1, and J. E. Shirley

Summary

Total blood protein measured in calvesbetween 1 and 7 days of age is a good indica-tor of the sufficiency of colostral intake andlevel of immunity passed to the calf. Thismeasurement can be used to improve calfmanagement strategies and thereby calfperformance. Total blood protein concentra-tions are associated with immunoglobulinabsorption in the neonatal calf, which canimpact calf morbidity and mortality. Bloodprotein >5.5 g/dl indicates sufficient immu-noglobulin absorption, and blood protein<5.0 g/dl indicates insufficient absorption.Insufficient immunoglobulin absorptionincreases the risk of calf morbidity andmortality. The dry cow health program,proper collection, and management ofcolostrum help ensure that quality colostrumis available for the newborn calf. Propercolostrum administration and low-stress calfmanagement also ensure maximal immuno-globulin absorption. Timing of colostralintake affects total blood protein concentra-tions. The calf’s ability to absorbimmunoglobulins is reduced significantly 12hr after birth. Therefore, it is critical toadminister colostrum during the first fewhours of life. Total blood protein can be usedto determine if the calf has absorbed suffi-cient immunoglobulins from the colostrum.

(Key Words: Blood Protein, Colostrum,Calves, Morbidity.)

Introduction

Dairy producers have to deal with manyfactors related to rearing baby calves.Colostrum management is one of them.Many producers attempt to increase theefficiency of their farm enterprise. Whentime traditionally spent in calf managementis re-allocated to other areas of the farm, calfhealth and performance may be impactednegatively. However, colostral management,including quality and timing of the firstfeeding of colostrum, is vital. It is welldocumented that administering an acceptablequality and quantity of colostrum within thefirst few hours of a calf's life greatlyincreases its level of immunity. Calves withsufficient colostral intake are less likely toexperience morbidity than calves with insuf-ficient intake.

Colostral management on some dairiesincludes commingling of first-, second-, andthird-day colostrum into one tank. Becausefirst-day colostrum has the highest concen-trations of immunoglobins, the poolingpractice results in a diluted mixture that maybe inadequate to meet the calf's immunoglob-ulin requirements. Colostrum <50 mg/ml(measured by a co los t rometer )should not be given to calves during the first12 hr of life, because the amount ofimmunoglobulin is likely to be inadequate.By measuring total blood protein fromindividual calves, producers candetermine accurately the amount ofimmunoglobulin absorption (r = 0.88) passed


24

from colostrum to the calf, thus, evaluatingthe level of passive immunity. Our objectivewas to review recent research concerning theuse of total blood protein as an indicator ofcolostral sufficiency and morbidity in dairycalves.

Review of Research

One method of testing the level of immu-nity passed to the calf is to measure serumtotal protein (TP). This is done by collectingblood from a jugular vein of a calf between1 and 7 days of age. The blood is centri-fuged, and the serum is analyzed for TPusing a refractrometer calibrated for thispurpose. Refractometery provides rapid andinexpensive results and is useful for monitor-ing passive immunity status.

Study results have shown that the rela-tionship between the level of serum TP andmorbidity and mortality of the calf is non-linear. One study reported that calves withTP concentrations >6.5 g/dl had the leastlevel of risk, whereas calves with TP <5.0g/dl were 3 to 6 times more likely to experi-ence health problems, death, or both. Amuch greater reduction in risk was observedwhen TP increased from 4.0 g/dl to 5.0 g/dlthan when it increased from 5.5 g/dl to 6.5g/dl. The hazard mortality ratio was a con-stant value from birth to 6 mo. This ratioindicates that low concentrations of TP were

associated with high mortality throughoutthat entire period. Data collected from an-other group show similar results; the lowestrisk for morbidity and mortality was detectedin calves with TP >5.5 g/dl. Calves withconcentrations of 5.0 g/dl to 5.4 g/dl showeda very slight increase in the risk of morbidityand mortality with the highest risk resultingfrom TP <4.0 g/dl. Therefore, we recom-mend maintaining TP >5.5 g/dl in calves fordecreased risk of subsequent health prob-lems.

These results cannot predict which calveswill get ill or die and which calves will not.Some calves with TP >6.0 g/dl will experi-ence health problems or die, but not at therate of calves with lower TP concentrations.Serum TP is a useful and practical means ofassessing immunoglobulin absorption in theneonatal calf. However, one also must payspecial attention to all factors associated withrearing calves. Following proper herd healthprograms is important to help ensure the bestperformance. Herd health programs shouldbe tailored for the individual dairy and ad-dress the problems of that dairy. Solving theproblems of low quality colostrum, as well asthose in the timing and amount of colostrumadministered, will not eliminate neonatalmorbidity and mortality. However, it is anessential step in helping to ensure moreadequate, healthy, replacement heifers forthe future.


1Food Animal Health and Management Center.2Department of Clinical Sciences.3WestAgro, Inc., Kansas City, Missouri.

25

Dairy Day 2000

ANTIBIOTIC VERSUS NONANTIBIOTIC PRODUCTS FOR THETREATMENT OF PAPILLOMATOUS DIGITAL DERMATITIS

(HAIRY HEEL WART) IN DAIRY CATTLE

J. M. Sargeant 1, D. P. Gnad 2, J. E. Shirley,J. Isch, H. Bathina 3, and J. Lising 3

Summary

A field trial was conducted to compareoxytetracycline to three nonantibiotic thera-pies using bandage protocols for the treat-ment of hairy heel warts. Affected feet werebandaged for 4 days with either of the fourproducts. Over a 28-day period followingbandage removal, heel warts on 44 cows (11per treatment group) were evaluated basedon size, degree of pain, color, and lesionappearance. No differences were detectedamong treatments, suggesting that nonanti-biotic therapies used in bandage protocolsmay be as effective as oxytetracycline.

(Key Words: Hairy Heel Warts, Therapy,Nonantibiotic.)

Introduction

Papillomatous digital dermatitis (hairyheel wart) is an emerging disease of dairycattle, which has become an important causeof lameness. A 1996 USDA survey reportedthat heel warts were detected in cows on43.5% of U.S. dairies. The presence of hairyheel warts is associated with severe lamenessand decreased performance because of pain.The cause of heel warts is not fully under-stood; however, it is believed to be conta-gious in nature and likely associated with aspirochete. Many methods have been used totreat hairy heel warts, including footbaths,topical sprays, parenteral antibiotics, andbandages. Oxytetracycline solution in abandaging protocol seems to offer the best

short-term improvement. However, thepotential exists for antibiotic residuals,though none have been reported in clinicaltrials, and for the development of antibioticresistance. Therefore, considerable interestexists in developing nonantibiotic productsthat are efficacious for the treatment of thisdisease.

The objective of this field trial was tocompare antibiotic and nonantibiotic treat-ment products used in a bandaging protocolfor the treatment of papillomatous digitaldermatitis.

Procedures

The study was conducted on a 300-headcommercial dairy farm in SE Kansas, in anarea that averages 37 inches of rain per yearand 190 frost-free days. The herd had expe-rienced an increased incidence of hairy heelwarts over the previous month. The milkingherd was housed in a shaded dry lot withsand-bedded free-stalls and concrete alleys.There were four milking strings, one for 2-year-old cows, and three for older cowsbased on production. The cows were walkedapproximately 150 ft on a grooved concretesurface twice daily for milking in a double-13 herringbone milking parlor. Foot bathshad not been used for several months andwere not used during the course of this study.Premilking heifers and dry cows werehoused separately in small groups on dirtdrylots with natural shade.


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All adult milking cows with active hairyheel wart lesions of at least 1 cm in diameteron a single day in March 2000 were enrolledin the trial. All affected cows were evaluatedin a standing position for pain and thenconfined in left lateral recumbency on a tilttable for further lesion evaluation and for thebandaging procedure. They were fitted withleg bands for identification throughout thetrial. The lesions were evaluated for size,pain, color, dermatological characteristics,and appearance based on protocols previ-ously developed for the standardized evalua-tion of hairy heel warts. The evaluationcriteria were as follows:

Lesion size . Lesions were measured intwo dimensions to the nearest 0.25 inch.Size was recorded as the square area of thelesion.

Pain. Scoring for pain was performedprior to restraining the animals on the tilttable. Pain was evaluated by spraying wateron the lesion with a hose spray attachmentfrom a distance of 2 ft. Prior to the actualmeasurement, both hind feet (or both frontfeet if the lesion was on a front foot) weresprayed to desensitize the animal to the waterapplication.

0 = no demonstrable pain (does not flinchor raise foot during spraying)

1 = sensitive (flinches and/or raises footfor less than 2 sec)

2 = severe (holds foot off ground for atleast 2 sec)

Color. 0 = flesh, indicating a healed lesion1 = black2 = gray3 = white4 = red

Lesion appearance.0 = healed1 = proliferative. Raised lesions with

many hair-like skin growths protruding fromthe surface. Hyperkeritinization of the skinand swelling are associated with maturelesions.

2 = granulomatous. Lesion containing aterry cloth-like texture associated with theintermediate stages of infection.

3 = ulcerative. Flat, red, and raw lesionoften involving bleeding, pain, and ery-thema; usually associated with lesions in theearly stages of infection.

Animals were allocated randomly to eachof four treatments, using permuted blocks offour to ensure equal numbers per group.Treatments A, B, and C represented differentnonantibiotic products, and treatment D wasoxytetracycline. The study was conducted ina triple blind manner; neither the herd owner,the person conducting the evaluations, northe person performing the statistical analysiswas aware of the active ingredient in eachtreatment.

Following cleaning of the lesion withwater, treatments were administered byadding 35 ml of each of four treatments to 10grams of cotton balls. The treatment-soakedcotton was placed against the lesion andbandaged in place using one roll ofVetwrap® and an outer layer of duct tape forwaterproofing. The bandages were removedafter 4 days.

Follow-up evaluations were performed atthe time of bandage removal (day 4) and atdays 18 and 32.

The effects of treatments on the overallchange in score for size, pain, color, andappearance categories were evaluated usingKruskal-Wallis one-way analysis of vari-ance. The outcome was calculated as thedifference between the score on day 1 and at28 days following bandage removal. Sepa-rate analyses were conducted for each cate-gory. The effect of treatment on the rate ofchange in each category over the course ofthe study was evaluated using repeated mea-sures analysis of variance for each category.Using these two statistical approaches al-lowed us to test for differences betweenoverall changes in the heel wart lesionsamong treatments and differences in the rateof change in the heel wart lesions amongtreatments over time.


1Department of Agricultural Economics.

29

Dairy Day 2000

ECONOMICS OF COOLING COWS TO REDUCESEASONAL VARIATION IN PEAK MILK PRODUCTION

K. C. Dhuyvetter 1

Summary

The economic impact of cooling cows toreduce the seasonal variation in peak milkproduction was estimated using research-based lactation curves and peak productionnumbers for a commercial dairy operation inKansas. Reducing the seasonal drop in peakproduction that occurs in the late summerand fall months by 29% or more is profitablefor second or higher lactation cows. Thisreduction represents an increase in total milkproduction over the entire lactation ofslightly over 1% and an increase in the aver-age annual peak production of only 1 lb.This indicates that achieving at least thebreakeven level for second and higher lacta-tion cows is a reasonable expectation. Basedon the peak milk production for the farmconsidered in this analysis, it would not payto cool first lactation cows, because theirpeak production was lower and exhibitedvery little seasonality. The economics ofcooling cows is insensitive to feed prices,and only moderately sensitive to milk pricessuggesting that the decision to cool dairycows is basically independent of these fac-tors. Although the benefit of cooling dairycows, in terms of increased production, willdepend on the type and effectiveness of thecooling system used, this analysis indicatesthat even small improvements in productioncan be economical.

(Key Words: Economics, Heat Stress, Cool-ing Cows.)

Introduction

Heat stress can have a large impact oncow comfort and milk production, therebyimpacting the profitability of dairy opera-tions. Drops in milk yield of 10-25% follow-ing heat stress are not uncommon in high-producing herds. With production decreasesof this magnitude, providing supplementalcooling to avoid, or at least minimize, theimpact of heat stress, most likely will beeconomical. However, in order for produc-ers to make informed decisions, they needquantitative information; thus, an economicanalysis that quantifies the returns associatedwith cooling cows (i.e., heat-stress abate-ment) is warranted.

Studies examining the returns to reducingheat stress often consider the heat-stress timeperiod only. However, published lactationcurves suggest that a 1-lb increase at peakproduction will produce an additional 225 to250 lb of milk over the entire lactation.Therefore, any economic analysis of heat-stress abatement should account for theincreased production over a cow’s entirelactation. The purpose of this study was toestimate the economic returns associatedwith reducing, or even eliminating, seasonalvariation in peak milk production for a com-mercial dairy herd in Kansas using a hypo-thetical research-based milk lactation curveto simulate milk production and the costsassociated with a fan and sprinkler-basedcooling system.


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Procedures

A partial budget was used to examine theimpact of heat-stress abatement (i.e., addingcooling equipment) on net returns. A partialbudget includes four values: 1) increasedrevenue, 2) decreased costs, 3) increasedcosts, and 4) decreased revenue. For thedairy analyzed here, increased revenue issimply the increased milk production fromreducing heat stress. Quantifying the costsexpected to decrease from reducing heatstress is difficult, and such costs likely varyconsiderably between operations. Costs thatmight decrease as a result of reduced heatstress are those associated with health andreproduction, i.e., those factors directlyrelated to cow comfort. Because of the diffi-culty in measuring these costs accurately,they are not included in this analysis, and asa result the returns associated with heat-stress abatement should be viewed as lowerbounds. Increased costs associated withcooling cows are the higher feed costs fromincreased feed intake and fixed and variablecosts of the cooling system itself (deprecia-tion and interest on fans and sprinklers, aswell as electricity and water costs). It isassumed that no reductions in revenue areassociated with cooling cows.

Figure 1 shows daily milk production asa percent of peak production for a hypotheti-cal research-based lactation curve. Usingthis approach, total milk production over theentire lactation will be a function of peakproduction. Therefore, increasing peakproduction will increase daily milk produc-tion at each day. For example, a cow thatpeaks at 100 lb/day will have proportionatelyhigher production every day of her lactationthan a cow that peaks at 90 lb/day. Further-more, because these lactation curves areproportionate, a peak that is 10% lower (e.g.,90 lb/day vs. 100 lb/day) will result in totalmilk production over the entire lactation thatis also 10% lower.

Figure 2 shows the peak milk productionby lactation and month for a commercialdairy operation in Kansas with freestall barnsbut not using any fans or sprinklers for cool-ing cows. The interpretation of the data in

Figure 2 is as follows – the average peakmilk production (lb/cow/day) for all cows intheir second lactation that peaked in themonth of March was 100 lb. Peak produc-tion was relatively steady for 7 mo of theyear (December through June), but it wasless for the other 5 mo, and considerably soin August, September, and October. Thereductions in peak production for cows intheir second lactation were similar to those intheir third or higher lactations on a percent-age basis -- about a 13% to 14% differencebetween highest and lowest peaks. Thedecrease in first-lactation cows followed asimilar seasonal pattern but was considerablyless (4% difference between highest andlowest peaks). A logical question then is:How much would it be worth to reduce, orpossibly eliminate, the reduction in peakproduction that occurs in July through No-vember by cooling cows? Using partialbudgets and the lactation curve shown inFigure 1, the economic return to reducing theseasonal variation in peak production asdisplayed in Figure 2 was estimated to an-swer this question.


The dashed lines in Figure 2 representwhat the peak production would be if the“gap” between the heat stress months (Julythrough November) and the average of Janu-ary through June were reduced by 50%.Table 1 shows the returns to reducing thevariability in peak production for first, sec-ond, and third and higher lactation cows atthree “gap reduction” levels. Economicreturns are based solely on changes in milkproduction and do not account for any repro-ductive or health benefits that might beassociated with cooling cows. Production isshown for 1) base peak production levels,i.e., the solid lines in Figure 2; 2) a 25%reduction in the gap between heat stressmonths and January through June; 3) a 50%reduction in the gap, i.e., the dashed lines inFigure 2; and 4) a 100% reduction in the gap,i.e., the elimination of seasonal variation inpeak production. Increased feed costs werebased on an additional 0.40 lb of feed foreach additional lb of milk. Costs of thecooling system were based on fixed and


variable costs of fans and sprinklers operatedfor 100 days per year. In addition to returnsover feed costs, a benefit/cost ratio wascalculated that simply looks at the dollars ofrevenue that are generated for every dollar ofexpense. Defined this way, a ratio of lessthan 1.0 would be unprofitable.

Given that the peak production of firstlactation cows was considerably less thanthat of older cows and very little seasonalityoccurred in peak production, cooling thesecows is not profitable when all costs areincluded (i.e., benefit/cost ratio <1.0). Com-pletely eliminating the seasonal variation,i.e., a 100% gap reduction, increases totalmilk production by less than 1%. However,returns over feed costs are positive ($13.11per cow per year), indicating that this smallincrease in production is sufficient to pay forthe added feed cost.

Cooling second and higher lactation cowsat relatively small percentage improvementsis economical. The breakeven over totalcosts is about a 29% reduction in the gap,which represents an increase in total milkproduction of slightly more than 1% and anincrease in the annual average peak produc-tion of only 1 lb. If the difference (i.e., gap)in peak production between heat stressmonths and other months can be reduced by50% for older cows, the payback is greaterthan 1.5:1. This compares to a payback ofonly 27¢ for every dollar spent on coolingfirst lactation cows at this gap-reduction

percentage. This indicates that the profitabil-ity of cooling cows will depend on the agedistribution of the herd. At a 50% reductionin the gap, a dairy that has an equal distribu-tion of first, second, and third+ lactationcows in the herd would recognize a return ofnearly $1.25 for every $1 spent on expensesassociated with cooling cows. Furthermore,if the cooling equipment were used only onhigher lactation cows, the returns would beabout $1.75 for every $1 spent. Thus, giventhat most dairies have second or higherlactation cows, management strategies thatincrease peak production by reducing theeffects of heat stress most likely will beprofitable.

Prices of feed and milk were varied fromtheir initial levels to determine how sensitivereturns were to these two factors. Decreasingmilk prices from $12/cwt to $11 and $10/cwtresulted in breakeven gap reductions forsecond and higher lactation cows of 32% and36%, respectively (initial breakeven was29%). Increasing feed costs from $120/tonto $150 and $180/ton increased the break-even percentages to 30% and 33% respec-tively. Thus, the decision to cool cows isrelatively insensitive to both of these factorsand especially so to feed prices. This sug-gests that for high-producing dairy herds,cooling cows over a wide range of feed andmilk prices and with relatively small im-provements in production most likely will beeconomical.

Figure 1. Hypothetical Research-Based Lactation Curve.

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33

Dairy Day 2000

MONENSIN: AN OVERVIEW OF ITS APPLICATIONIN LACTATING DAIRY COW DIETS

J. M. DeFrain and J. E. Shirley

Summary

The efficiency of feedstuff utilization byruminal microorganisms and the cow’sgenetic ability to convert feed nutrients intomilk and milk components are major factorsthat influence the profitability of a dairyherd. Monensin’s ability to modify themovement of ions across biological mem-branes leads to alterations in bacterial popu-lations and subsequent changes in the pro-portion of volatile fatty acids produced dur-ing ruminal fermentation. Manipulatingruminal microbial populations withionophores has the potential to improveperformance by reducing ketosis, acidosis,and bloat and increasing digestive efficiency.Monensin improves fiber digestion by pre-venting suboptimal ruminal pH, enhancesamino acid use by reducing the degradationof dietary protein, and improves the energystatus of periparturient animals. Monensin isnot approved for use in diets for lactatingdairy cows at this time, but its status is cur-rently under review by the U.S. Food andDrug Administration. If approved, monensinwill provide another management tool to thedairy industry.

(Key Words: Ionophore, Health, Efficiency.)

Introduction

The profitability of a dairy herd is afunction of the mail box price at the farmlevel and the cost of production (overheadand operational). The herd manager caninfluence the cost of production but has littleinfluence on the price received for milk. Ananalysis of individual items contributing tothe total cost of production reveals that feedcost constitutes approximately 50% (range of

35-60%). Thus, the efficient use of feed-stuffs is a high priority issue for dairy pro-ducers and researchers.

Feed efficiency is defined herein aspounds of energy-corrected milk producedper pound of feed consumed. Energy-cor-rected milk is used, because it accounts forvolume and energy content of milk (fat,protein, and lactose). Feed consumed is lessthan feed offered, but feed wasted duringhandling and feeding is a separate manage-ment issue. Milk and milk component yieldby the dairy cow is a function of her geneticmakeup and environment. The diet fed to thecow is a major aspect of the environmentalfactors that influence her performance. If weassume that the cow is fed a properly formu-lated diet and other environmental factors arefavorable, then her response to the diet de-pends on the efficiency of feedstuff utiliza-tion by ruminal microorganisms and thecow’s genetic ability to convert feed nutri-ents into milk

The purpose of this review is to explorethe implications of including monensin indiets for lactating dairy cows, because it isunder review by the U.S. Food and DrugAdministration (FDA) as a potential feedadditive.

Monensin’s Mode of Action

Monensin and other ionophores havebeen used as growth promotants in livestockproduction systems for decades. However,monensin is known most notably for itsability to alter the ruminal microbial popula-tion, leading to increased proportions of thegluconeogenic precursor propionate. Anionophore’s mode of action is to modify the


34

movement of ions across biological mem-branes. Two major classes of bacteria existin the rumen: gram negative and gram posi-tive. Gram positive bacteria (cells possess-ing a complex outer membrane) are resistantto ionophores, whereas gram negative bacte-ria are susceptible. Bacterial cell membranesconsist of a lipid bilayer that regulates nutri-ent exchange across the membrane.Ionophores bind to gram-negative bacteriaand disrupt nutrient exchange that interfereswith proper cell function and can result incell death. Alterations in bacterial popula-tions lead to changes in the proportions ofvolatile fatty acids (VFAs) produced duringruminal fermentation.

Effects on Animal Health Status

Management tools such as DHI records,rBST, and a solid preventive herd healthprogram play a vital role in achieving higherproduction efficiencies. Monensin is yetanother management tool that could enhanceproduction efficiency and improve animalhealth status. As the dairy cow progressesthrough various production phases (i.e., dryperiod, early, mid-, and late-lactations) sheexperiences a wide array of physiologicaland dietary changes. These changes requireintense nutritional management to preventherd health problems and maximize perfor-mance. Manipulating the ruminal microbialpopulation with ionophores could improveperformance by reducing ketosis, acidosis,and bloat and increasing digestive efficiency.

The transition from a nonlactating to alactating state increases nutrient demand at atime when intake is less than optimal. Thecow responds by mobilizing tissue to supportlactation, which increases the risk of meta-bolic disorders such as ketosis and fatty liver.Monensin has the potential to reduce theincidence of ketosis, because it increases theproportion of propionate, a gluconeogenicprecursor, whereas total ruminal VFA con-centrations either increase or remain un-changed. Increasing ruminal production ofpropionate (contributes to glucose produc-tion) reduces the need to synthesize glucose

from the amino acid pool in order to main-tain adequate concentrations of blood glu-cose.

Feeding diets containing an adequatesupply of nonstructural carbohydrates tomeet the lactational demand of the high-producing dairy cow often predisposes theanimal to borderline acidosis. The initialonset of ruminal acidosis stems from anoverproduction of VFAs that lowers ruminalpH (<5.5). This affects the ruminal micro-bial population, allowing lactic acid produc-ers to outnumber lactic acid utilizers.Monensin decreases the Streptococcus bovispopulation, a major lactate producer, andenhances the lactic acid utilizers. The neteffect of monensin on ruminal acidosis yieldsa more desirable ruminal pH (<5.8) for im-proved fiber digestion.

Monensin also has demonstrated theability to reduce bloat. Two major productsresulting from ruminal fermentation are acidsand gases. The inability to eructate free gasfrom the rumen results in bloat. This inabil-ity is caused by an accumulation of fluids,solids, foam, and(or) slime that prevents thefree gas from reaching the cardia to be ex-pelled via eructation. Monensin reduces theproduction of methane, and carbon dioxide,the rate of rumen fill, and growth of micro-bial species responsible for slime production.A reduction in these bloat-provocative sub-stances reduces the incidence of bloat withinthe herd.

Monensin also has a protein-sparingeffect and reduces ruminal ammonia produc-tion. Its depressive effect on overall ruminalcell numbers reduces activities of proteolyticand deaminative enzymes, thus, increasingthe quantity of dietary protein escapingruminal degradation. This dietary proteinthen would be available for postruminalabsorption. Other researchers have foundthat monensin reduces protozoan numbers invivo. Because protozoa play a role in bacte-rial protein recycling, ruminal ammoniaconcentration is lower for cattle receivingmonensin.


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Feeding Recommendations

Monensin has not been cleared for use inlactating dairy cow diets in the U.S. How-ever, data have been submitted to the U.S.Food and Drug Administration for review.Monensin has been cleared for use in othercountries, and the feeding recommendationscontained herein are based on their findings.

The impact of monensin on the digestionof other dietary ingredients should be consid-ered. Incorporating monensin into a high-fiber diet generally will result in increasedmilk production because of increased energy(in the form of glucose) available for milksynthesis. However, when monensin isformulated into an energy-dense diet, drymatter intake is reduced and milk productionunchanged, resulting in increased productionefficiency. Monensin also improves proteinnutrition of the dairy cow, because moreamino acids are absorbed postruminally andmade available for milk protein synthesis orgluconeogenesis rather than being degradedby ruminal microbes. This protein-sparingeffect is primarily due to a reduction in pro-tein deamination activity in the rumen, mak-ing more effective use of amino N. There-fore, diets designed for monensin inclusionshould contain sufficient high quality proteinto ensure the availability of essential aminoacids.

Because monensin enhances the energystatus of the cow, the greatest response tofeeding monensin is observed during the first3 to 4 wk after calving and continues untilpeak milk production. During the immediateprepartum period, the cow is in a negativeenergy balance as fetal growth is maximizedand the mammary gland is preparing for the

subsequent lactation. This energy imbalancecontinues during early lactation. Therefore,the positive effect of monensin on perfor-mance will continue until peak lactation(usually 50 to 60 days postpartum). Shortlyafter this time, feed intake is sufficient tomeet the demand for milk synthesis. Gener-ally, no response in milk production has beenobserved after peak milk production butincreases in body weight and body conditionresulted from the increased energy availableto the cow.

The amount of monensin to include inthe diet will be determined during the FDAreview process. Doses used in research trialshave ranged from 10 ppm (equivalent to 10mg/kg of feed dry matter) to 450 mg perhead per day. Research indicates that an in-teraction may occur between dose and otherfactors such as diet and stage of lactation. Ingeneral, feeding monensin at differentamounts has decreased milk fat percentagebut had an insignificant effect on milk pro-tein content. Feeding monensin under condi-tions known to decrease milk fat (low fiber,high grain diets, and heat stress) has shownthe greatest negative impact on milk fat.

In conclusion, a recent review indicatedthat monensin increased milk yield by ap-proximately 2 lb per day. Most importantly,monensin could be useful in the preventionof periparturient diseases, which are often-times invisible costs impacting the efficiencyof production. If it is approved for use in theU.S., diet formulation strategies will varybetween farms based on production goals. Inthe end, monensin’s impact on the efficiencyof milk production should help improve thedairy farm balance sheet.


36

Dairy Day 2000

EFFECT OF LEVEL OF SURFACE-SPOILEDSILAGE ON THE NUTRITIVE VALUE OF

CORN SILAGE-BASED RATIONS

L. A. Whitlock, M. K. Siefers, R. V. Pope,B. E. Brent, and K. K. Bolsen

Summary

Twelve ruminally cannulated crossbredsteers were used to determine the effect oflevel of surface spoilage in corn silage-basedrations on dry matter (DM) intake and nutri-ent digestibilities. Irrigated corn was har-vested at the 80% milkline stage of maturityand ensiled in pilot-scale bunker silos, whichwere 3 ft in depth, and a 9-ft-diameterAgBag®. After 90 days, the bunkers weresealed with a single sheet of polyethylene,and this silage was designated “spoiled”. Thesilage in the AgBag was designated “nor-mal”. The four rations contained 90% silageand 10% supplement (DM basis), and theproportions of silage in the rations were: A)100% normal; B) 75% normal: 25% spoiled;C) 50% normal: 50% spoiled; and D) 25%normal: 75% spoiled. Dry matter intakedecreased in a linear manner as the propor-tion of spoiled silage increased from 0 to75%. Steers consuming the normal silageration had higher DM, organic manner, crudeprotein, neutral detergent fiber, and acid det-ergent fiber digestibilities than those fed thethree rations that contained spoiled silage.The addition of surface-spoiled silage alsohad negative associative effects on nutrientdigestibilities, and the integrity of the foragemat in the rumen was destroyed partially byeven the lowest level of spoiled silage.

(Key Words: Corn Silage, Surface Spoilage,Nutritive Value.)

Introduction

A silage management practice sometimesoverlooked by dairy producers is the discard-ing of spoiled silage. Because sealingbunker, trench, and drive-over pile silos

with a polyethylene sheet is not 100% effec-tive, aerobic spoilage occurs to some degreein virtually all sealed silos. The objective ofthis study was to determine the effect ofincluding three levels of “surface-spoiledsilage” on the nutritive value of whole-plantcorn silage-based rations.

Procedures

Twelve crossbred steers, fitted withruminal cannulas, were used in the study. Asingle source of irrigated corn (Pioneer 3394)was harvested at the 80% milkline stage ofmaturity and chopped to a 10 mm particlelength. Three pilot-scale bunker silos, whichwere approximately 3 ft in depth, and a 30-ftsection of a 9-ft diameter AgBag® were filledwith alternating loads of chopped forage.After 90 days, the bunkers were sealed withsingle sheets of 0.6 mil polyethylene, andthese silages were designated “spoiled”. Thesilage in the AgBag® was designated as “nor-mal”. The four experimental rations con-tained 90% silage and 10% supplement (on aDM basis), and the proportions of silage inthe rations were: A) 100% normal, B) 75%normal:25% spoiled; C) 50% normal:50%spoiled, and D) 25% normal:75% spoiled.The rations were fed once daily at 0700, andthe amount fed was adjusted so that approxi-mately 10% of the as-fed ration was in thefeed bunk at the end of each 24-hr period.


The pH and chemical composition of thewhole-plant corn silages fed are shown inTable 1. The composition of the spoiledsilage is reported for each of the two distinctvisual layers, designated as the original top18 inches and bottom 18 inches, and for a


composite of the two layers after they weremixed, which represents the spoiled silage asit was actually fed in rations with 25%, 50%,or 75% spoilage. With ash content as theinternal marker, the estimated proportions ofthe original top 18-inch and bottom 18- inchspoilage layers in the spoiled compositesilage were 23.8 and 76.2%, respectively.The normal corn silage had higher DM andOM contents and slightly lower starch andCP contents than the spoiled compositesilage. The normal corn silage also had lowNDF and ADF percentages, which reflect thehigh proportion of grain in the ensiled crop.The high ash and fiber contents of the spoiledcomposite silage are associated with poorpreservation efficiency and very high OMlosses during the aerobic, fermentation, andstorage phases.

The original top 18-inch layer was visu-ally quite typical of an unsealed layer ofsilage that has undergone several months ofexposure to air and rainfall. It had a foulodor, was black in color, and had a slimy,“mud-like” texture, and its extensive deterio-ration during the 90-day storage also wasreflected in very high pH, ash, and fibervalues. The “slime” layer comprised 5.4,10.7, and 16.0 % of the DM in rations with

25%, 50%, or 75% spoilage, respectively.The original bottom 18-inch layer had anaroma and appearance usually associated-with wet, high-acid, corn silage - a brightyellow to orange color, a low pH, and a verystrong acetic acid smell.

The original depth of the packed, whole-plant corn in the bunker silos was about 36inches; however, the final depth of thespoiled silage was only about 22 inches, withabout 7 and 15 inches in the top and bottomdepths, respectively (Figure 1). This settlingof the ensiled crop that occurred during the90 days the bunker silos remained unsealed- approximately 14 inches - is typical ofsettling depths observed in unsealed bunker,trench, or drive-over pile silages.

The addition of surface-spoiled silagehad large negative associative effects on feedintake and DM, OM, NDF, and ADFdigestibilities (Table 2), and the first incre-ment of spoilage had the greatest negativeimpact. Examination of ruminal contentsshowed that the spoiled silage also had par-tially or totally destroyed the integrity of the“forage mat” in the rumen. The resultsclearly showed that surface spoilage reducedthe nutritive value of corn silage-based ra-tions more than was expected.

Figure 1. Surface-Spoiled Silage with a Slimy Layer of 7 Inches (Top) and an AcidicLayer of 15 Inches (Bottom).

37


38

Table 1. pH and Chemical Composition of the Whole-Plant Corn Silages Fed in theMetabolism Trial

Silage pH DM OM Starch CP NDF ADF

% ---------------- % of the DM ----------------

Normal 3.90 38.0 94.7 22.3 6.9 42.6 23.4

Spoiled top layer, composite of the original top 36 inches 4.79 26.4 90.9 24.3 9.9 48.9 31.0

Spoilage layers

Original top 0-18 inches (slime layer) 8.22 19.1 80.0 2.7 17.7 57.6 48.3

Original top 18-36 inches (acidic layer) 3.67 27.6 94.3 26.1 6.7 48.5 25.5

DM = dry matter, OM = organic matter, CP = crude protein, NDF = neutral detergentfiber, ADF = acid detergent fiber.

Table 2. Effect of the Level of Spoiled Silage on Nutrient Digestibilities for Steers Fedthe Four Whole-Plant Corn Silage Rations

Ration

% Spoiled silage 0 25 50 75

Item (% Slimy layer) (0) (5.4) (10.7) (16.0)

DM intake, lb/day 17.5a 16.2b 15.3b,c 14.7c

DM intake, % of body weight 2.36a 2.22b 2.10b,c 2.04c

-------------------------- Digestibility, % --------------------------

Dry matter 74.4a 68.9b 67.2b 66.0b

Organic matter 75.6a 70.6b 69.0b 67.8b

Crude protein 74.6a 70.5b 68.0b,c 62.8c

Neutral detergent fiber 63.2x 56.0y 52.5y 52.3y

Acid detergent fiber 56.1a 46.2b 41.3c 40.5c

a,b,cMeans within a row with no common superscript differ (P<.05).x,yMeans within a row with no common superscript differ (P<.10).


39

Dairy Day 2000

INTAKE AND PERFORMANCE OF DAIRY COWSFED WET CORN GLUTEN FEED DURING THE

PERIPARTURIENT PERIOD

A. F. Park, J. M. Defrain, M. J. Meyer,J. E. Shirley, E. C. Titgemeyer, T. T. Marston,

J. F. Gleghorn, and L. E. Wankel

Summary

Eight primiparous and nine multiparousHolstein cows were used in a randomizedblock design to determine the effect of wetcorn gluten feed in the diet during the last 21days of gestation on dry matter intake andearly postpartum performance. Multilacta-tion cows fed wet corn gluten feed main-tained a higher dry matter intake and intakeas a percentage of body weight during thelast week before calving than cows fed thecontrol diet. First-lactation cows fed wetcorn gluten feed consumed less dry matter,both total and as a percentage of bodyweight, across calving than first-lactationcows fed the control diet. Milk, milk compo-nents, and blood metabolites were not influ-enced by diet. Wet corn gluten feed mayhelp alleviate the depression in intake typi-cally observed during late gestation formultiparous but not primiparous cows.

(Key Words: Wet Corn Gluten Feed, Transi-tion Cow, Intake.)

Introduction

The 30% decrease in dry matter (DM)intake often observed in dairy cows duringthe last week before calving is of interest,because it appears to be associated with anincrease in body fat mobilization, the onsetof fatty liver, and a lower DM intake aftercalving. The exact cause of this depressionin intake and its physiological role remainunclear. Efforts to reduce the severity of thisintake depression or reduce its effects onnutrient balance have not been very success-ful.

Wet corn gluten feed (WCGF) increasedDM intake and milk yield in two lactating-cow studies at Kansas State University. Theobserved improvement in intake may havebeen due partially to an increase in dietaryfiber digestibility and a positive effect onruminal pH as reported by others. If this isthe case, then its inclusion in close-up dietsmight reduce the severity of the observedprepartum intake depression and enhanceDM intake immediately after calving. Ourobjective was to evaluate the effect of wetcorn gluten feed on DM intake and perfor-mance of dairy cows during theperiparturient period.

Procedures

Eight primiparous and nine multiparousHolstein cows were used in this study. Cowswere randomly assigned to a 20% WCGFdiet (DM basis) or control diet (Table 1).Cows were housed in a tie-stall barn, andexperimental diets fed from 21 days prior toprojected calving date until calving. Allcows received a common diet after calving.Cow performance was measured through 4wk postpartum. Daily feed intakes, milkweights, and body weights were recorded forindividual cows. Body condition scores wereassigned weekly (1 = thin and 5 = fat). Milksamples (AM , PM , and composite) were ob-tained on day 6 of lactation, and the contentsof protein, fat, lactose, solids-not-fat, milkurea nitrogen (MUN), and somatic cells weredetermined by the Heart of America DHILaboratory, Manhattan, KS. Blood sampleswere collected from the tail vein on days 21,3, and 1 prior to projected calving, and ondays 1, 2, 6 and 10 postpartum.


40


The experimental diets and their chemi-cal composition are shown in Tables 1 and 2,respectively. Expeller soybean meal(Soybest) replaced solvent soybean meal inthe WCGF diet to balance ruminally degrad-able protein, and WCGF replaced a portionof the alfalfa hay and corn grain. TheWCGF diet contained more moisture thanthe control diet and was higher in neutraldetergent fiber but similar to the control dietin acid detergent fiber. The diets were simi-lar in NEL, because the control diet containedless fat and more nonfiber carbohydrates.

The average DM intakes during the pre-and postpartum periods were numerically,but not significantly, higher for primiparouscows fed the control diet (Table 3). First-lactation cows fed WCGF tended (P=0.15) tobe heavier than those fed the control diet, butbody condition was similar between treat-ments. Multilactation cows were similar inbody weight and average DM intake duringthe pre- and postpartum periods, but thosefed WCGF tended to lose more body condi-tion during the first 30 days after calving.The difference in apparent DM intake re-sponses between first- and multilactationcows fed WCGF may have resulted from thedifference in nonfiber carbohydrate contentof the two diets. The working hypothesisthat fiber digestibility of the WCGF wouldbe sufficient to offset the reduction in non-fiber carbohydrates that occurred when itreplaced part of the corn grain in the dietseems to fit multilactation but not first-lacta-tion cows. Irrespective of diet, DM intakesaveraged 25.8 and 39.5 pounds per headdaily during the prepartum period for first-and multilactation cows, respectively. Oldercows also consumed more DM as a percentof body weight than first-lactation cows(2.41 vs 1.85%). Because intake in first-lactation cows is limited by body capacity,body condition, or both, they may be moreresponsive to diets higher in starch thanmultilactation cows.

Including WCGF in lactating cow dietsimproved DM intake in earlier studies.These results provided the basis for this

study, because of the current interest in thedepression in DM intake routinely observedprior to calving. The use of WCGF inprepartum diets may offer a means of main-taining dietary fiber, while improving nutri-ent delivery to the cow because the fiberfraction of WCGF is hypothesized to bemore digestible than alfalfa fiber. The multi-parous cows responded to WCGF as ex-pected; DM intake decreased by 8% between1 and 2 wk prepartum compared to a 16%decrease for control cows. Conversely, first-lactation cows fed WCGF experienced a23% drop in intake between 1 and 2 wkprepartum compared to an 11% decrease forthose fed the control diet. The decrease inDM intake observed for all cows was lessthan the 30% often reported, because ourvalues represent the decrease experiencedbetween the average intake during days 7, 8,and 9 and days 1, 2, and 3 prepartum insteadof 1 to 3 wk prepartum.

Milk yield and composition data areshown in Table 4 and reflect the averagedaily milk yield for the first 30 dayspostpartum and milk composition on day 6postpartum. No differences were observed inmilk yield across treatments for either thefirst or multi-lactation cows. Milk composi-tion was variable among cows within treat-ments, and the number of cows used in thestudy was not sufficient to detect differencesexcept for somatic cells. Cows consumingWCGF had a higher somatic cell count thanthose consuming the control diet. Theseresults differ from the results of earlier stud-ies and may reflect the limited number ofobservations.

The most interesting observation in thisstudy was that milk yield during the first 30days of lactation was not affected by thedifference observed in prepartum intakedepression. We realize that this is a smallnumber of observations on which to make afinal judgement, but the results indicate thatthe degree of intake depression during theweek before calving may be insignificant asan indicator of postpartum performance.Further studies with larger numbers of cowsare warranted.


41

None of the cows in the study experi-enced clinical ketosis, milk fever, displacedabomasum, or dystocia. Calf birth weightswere not affected by WCGF in first-lactationcows (91 vs 88 lb, control vs WCGF, respec-tively), but multilactation cows fed the con-trol diet produced larger calves than cowsfed WCGF (104 vs 79 lb, respectively). Thereason for the observed difference in birthweights is not apparent from the data col-lected in this study. The multilactation cowswere similar in body weight, body condition,and average dry matter intake during the last

2 wk before calving. No treatment differ-ences occurred in plasma total alpha aminonitrogen, glucose, or urea nitrogen (Table 5)during the prepartum period.

In summary, cows fed WCGF during theclose-up dry period performed as well asthose fed a standard diet. Further researchwith other diet formulations and more cowsper treatment group is needed to clarify thebenefits or deficiencies derived from theinclusion of WCGF in diets for close-up drycows.

Table 1. Diet Compositions

Prepartum Diets Common

Ingredient Control WCGF1 Postpartum Diet

Alfalfa hay 15.0 12.5 30.0

Prairie hay 20.0 20.0 -

Corn silage 23.0 23.0 14.5

Whole cottonseed - - 9.6

Wet corn gluten feed - 20.0 -

Corn grain, ground 30.2 13.4 32.4

Soybean meal, 48% CP 9.1 - 5.1

Soybest3 - 8.5 4

Wet molasses - - 1.2

Vit./min. premix2 2.7 2.6 3.2

1 Wet corn gluten feed.2Vitamin and mineral premix = dical; limestone; Na bicarbonate; Mg oxide; trace

mineralized salt; vitamins A, D, E; and selenium.3Expeller soybean meal.


42

Table 2. Chemical Compositions (% DM) of Experimental Diets

Prepartum Diets Common

Nutrient Control WCGF1 Postpartum Diet

Dry matter, % 77.2 68.0 81.5Crude protein, % 13.9 14.3 16.8RUP2, % of DM 5.55 5.95 7.73NEL , Mcal/lb 0.68 0.67 0.77Fat, % 3.04 3.66 4.78Neutral detergent fiber, % 36.4 42.6 29.1Acid detergent fiber, % 21.5 22.7 19.4Nonfiber carbohydrate, % 39.1 31.4 41.4Calcium, % 0.85 1.13 1.21Phosphorus,% 0.48 0.46 0.55Sodium, % 0.22 0.17 0.37Potassium, % 1.33 1.37 1.41Chlorine, % 0.41 0.37 0.36Sulfur, % 0.15 0.19 0.18

1Wet corn gluten feed.2Rumen-undegraded protein.

Table 3. Prepartum and Postpartum MeasurementsPrepartum Postpartum

Item Control WCGF1 SEM Control WCGF SEM

First-lactation cows (n = 8) DMI2, lb/day 26.7 24.9 1.3 37.3 34.8 1.5 DMI as % of BW3 1.9 1.8 0.12 2.9 2.8 0.15 BW, lb 1385 1435 15 1283 1259 51 BCS4 3.6 3.5 0.11 3.2 3.3 0.2 Rectal temperature, °F 101.4 101.1 0.2 101.1 101.4 0.2 Urine pH 8.2 8.3 0.06 8.3 8.3 0.3 Fecal pH 6.86 6.90 0.06 6.4 6.5 0.06Multilactation cows (n = 9) DMI, lb/day 39 40 2.0 54.2 53.4 2.6 DMI as % of BW 2.43 2.39 0.09 3.7 3.4 0.14 BW, lb 1632 1634 29 1508 1524 31 BCS 3.0 2.9 0.2 2.8 2.6 0.09 Rectal temperature, °F 101.5 100.9 0.2 101.7 101.1 0.2 Urine pH 8.3 8.3 0.03 8.3 8.4 0.09 Fecal pH 6.6 6.7 0.08 6.3 6.4 0.09

1

1Wet corn gluten feed.

2

2Dry matter intake.

3

3Body weight.

4

4Body condition score (1 = thin and 5 = fat).


Publications

43

Table 4. Milk Production and Composition

Prepartum Diets

Item Control WCGF1 SEM

First-lactation cows (n = 8) Milk, lb/day 63.3 64.6 3.2 Fat, % 4.19 4.50 0.21 Protein, % 3.7 3.78 0.10 Lactose, % 4.81 4.69 0.05 SNF, % 9.34 9.29 0.14 SCC, × 1000a 140 191 42 MUN, mg/dL 9.90 10.51 1.14Multilactation cows (n = 9) Milk, lb/day 86.7 85.8 3.2 Fat, % 3.68 3.97 0.28 Protein, % 4.14 4.07 0.16 Lactose, % 4.55 4.69 0.09 SNF, % 9.46 9.56 0.15 SCC, x 1000a 190 360 11 MUN, mg/dL 11.46 11.80 0.77

11Wet corn gluten feed.*Different (P<0.01) from control diet.

Table 5. Prepartum Plasma Total Amino Acid Nitrogen (TAAN), Glucose, andPlasma Urea Nitrogen (PUN)

Prepartum Diets

Item Control WCGF SEM

First-lactation cows TAAN, mM 2.30 2.38 0.05 Glucose, mg/dL 73.2 72.9 1.8 PUN, mg/dL 8.8 9.3 0.5Multilactation cows TAAN, mM 2.3 2.4 0.09 Glucose, mg/dL 65.2 66.4 0.9 PUN, mg/dL 10.4 10.6 0.4


Publications

44

Dairy Day 2000

DETERMINATION OF THE AMOUNT OF WET CORNGLUTEN FEED TO INCLUDE IN DIETS FOR

LACTATING DAIRY COWS

M. J. VanBaale, J. E. Shirley, M. V. Scheffel,E. C. Titgemeyer, and R. U. Lindquist

Summary

Twenty-four multiparous Holstein cowswere used in six 4×4 Latin squares with 28-day periods to determine inclusion rates forwet corn gluten feed (WCGF) in diets forlactating dairy cows. Cows were housed in atie-stall barn and fed diets to meet or exceedNRC (1989) nutrient requirements. Experi-mental treatments were 1) control, 2) WCGFconstituting 20%, 3) WCGF constituting27.5%, and 4) WCGF constituting 35% ofthe diet dry matter. Cows fed WCGF con-sumed more dry matter (P<0.01) and pro-duced more (P<0.001) milk, energy-cor-rected milk, and fat-corrected milk than cowsfed the control diet. Dry matter intakes were58.9 lb/day for control and 60.2 lb/day forthose cows consuming WCGF diets. Cowsfed the control diet produced 83.2 lb/day ofmilk, whereas those fed WCGF diets pro-duced 91.5 lb/day. Production efficiencywas increased (P<0.001) on the WCGF diets.The percentage of fat in milk, total proteinproduction, and milk urea nitrogen werehigher (P<0.01) for cows fed WCGF dietsthan controls. Plasma glucose, total alpha-amino nitrogen, urea nitrogen, and trygly-cerides were similar between cows fed thecontrol and WCGF diets. No differencesoccurred in percentages of protein, lactose,or solids-not-fat content, nor was somaticcell count affected by the addition of WCGF.Body weight and condition score were notaffected by treatment. We conclude thatWCGF is an excellent feed for lactatingdairy cows when included in the diet at 20%,27.5%, or 35% of the dry matter.

(Key Words: Wet Corn Gluten, LactatingCows, Milk Yield.)

Introduction

Wet corn gluten feed (WCGF) is a poten-tial feedstuff for dairy cows located near asource. Data from studies conducted withfeedlot steers suggest that it improves aver-age daily gain and dry matter intake, reducesacidosis, and yields feed efficiency valuescomparable to those with corn. Wet corngluten feed is relatively low in starch (18 to22% of dry matter, DM), and high in neutraldetergent fiber (42% of DM), with a proteinfraction that is very degradable (65%) in therumen. Lactation diets formulated to com-plement these characteristics should optimizethe use of WCGF. The objectives of ourstudy were to evaluate the effects of WCGFon the performance of lactating dairy cowswhen it was substituted in the diet for aportion of the forage and corn grain and todetermine the optimal amount of WCGF toinclude in diets for multiparous, lactatingdairy cows.

Procedures

Twenty-four multiparous Holstein cowsaveraging 65 days in milk were used in six4×4 Latin squares with 28-day periods.Cows were housed and fed in a tie-stallfacility at the Kansas State University Dairy,Manhattan, KS, and were fed individuallydiets formulated to meet or exceed NRC(1989) nutrient requirements. Diets wereformulated to be isocaloric and isonitro-genous with similar amounts of neutral andacid detergent fiber, rumen-undegradableprotein (RUP), and DM. Alfalfa hay andcorn silage were used as forages, and corn asthe primary grain. Expeller soybean meal(Soybest, Grain States Soya, Delevan, KS),48% solvent soybean meal, and blood meal


45

were used to balance diets for RUP. Treat-ments were control (no WCGF) and WCGFat inclusion amounts of 20, 27.5, and 35% ofdiet replacing a mix of alfalfa hay, cornsilage, and corn grain.

Diets were fed free choice as a totalmixed ration and issued twice daily to ensure10% orts. Daily milk production and feedintake were recorded, and milk samples (AM-PM composite) were collected weekly andanalyzed for milk composition: milk protein,fat, lactose, solids-non-fat (SNF), milk ureanitrogen (MUN), and somatic cells (Heart ofAmerica DHI Laboratory, Manhattan, KS).Cows were weighed and scored for bodycondition at the beginning of the study and atthe end of each 28-day period. Body weights(BW) were obtained immediately after theAM milking on 2 consecutive days, and theaverage was used for analysis. Blood sam-ples were collected from the cooccygeal veinduring the final week of each period, and theharvested plasma was frozen at –4°F untilanalyzed for glucose, urea nitrogen, and totalalpha amino nitrogen (TAAN).


Cows fed WCGF produced more(P<0.01) milk and energy-corrected milk(ECM) than cows fed the control diet. Cowsfed diets containing 20 and 27.5% WCGF (%of DM) consumed more (P<0.05) DM as

a percentage of BW than cows fed the con-trol or 35% WCGF diet. The resulting in-crease in milk yield can be explained par-tially by the increase in DM intake, butproduction efficiency (lb milk/lb DM intake)also improved in cows fed WCGF. Milk fatpercentage was lower (P<0.05) in milk fromcows fed 20 and 35% WCGF compared tocontrols. Cows fed WCGF produced more(P<0.01) milk protein, SNF, and lactose thancows fed the control diet, primarily becauseof the increase in milk yield. Cows fed 27.5and 35% WCGF had greater (P<0.01) MUNthan cows fed control or 20% WCGF.

Somatic cell count, BW, and body condi-tion score were unaffected by dietary inclu-sion of WCGF. Plasma glucose, TAAN, andtotal triglycerides were similar among diets,but plasma urea nitrogen increased (P<0.05)when cows consumed WCGF. Fecal pHtended to be greater (P=0.06) for cows fedthe 27.5 and 35% WCGF diets, whereasurine pH decreased (P<0.05) when WCGFwas included in the diet.

In summary, WCGF substituted for a mixof alfalfa hay, corn silage, and corn grain indiets of multiparous Holstein cows increasedECM yield. Cows fed 35% WCGF (% ofDM) were most efficient, but intake andECM production data indicated that 27.5%WCGF (% of DM) is the optimum inclusionlevel.


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Table 1. Ingredients and Nutrient Compositions of Experimental Diets

Wet Corn Gluten Feed, % of DM

Ingredient 0 20 27.5 35

Alfalfa hay 30.0 20.0 20.3 18.4Corn silage 24.5 9.8 9.8 7.4Whole cottonseed 9.6 9.7 9.7 9.8Wet corn gluten feed - 19.2 26.5 33.6Corn grain, ground 32.4 26.7 20.7 18.3Soybean meal, 48% CP 5.1 2.0 0.5 -Expellers soybean meal 4.0 8.1 7.2 7.0Wet molasses 2.2 1.3 1.3 1.3Blood meal - - 0.75 0.90Vit./Min. premix1 3.2 3.2 3.3 3.3Nutrients Dry matter, % 81.7 75.0 71.3 69.2 CP2, % 16.7 17.3 17.7 17.9 RUP3, % of CP 36.1 37.2 36.7 36.6 NEL

4, Mcal/lb 3.75 3.84 3.75 3.84 Fat, % 4.9 5.4 5.4 5.6 NDF5, % 29.4 31.7 33.3 34.4 ADF6, % 19.6 17.8 18.3 17.8 NFC7, % 42.5 39.7 36.7 36.2

1Vitamin and mineral premix = dical; limestone; Na bicarbonate; Mg oxide; trace mineralsalt; vitamins A, D, E; and selenium.

2Crude protein.3Rumen undegradable protein.4Net energy for lactation.5Neutral detergent fiber.6Acid detergent fiber.7Nonfiber carbohydrate.


47

Table 2. Lactational Performance of Cows


Item 0 20 27.5 35 SEM

DMI1, lb/day 58.9bc 60.9ab 61.4a 58.3c 0.36

DMI, % of BW 4.25b 4.42a 4.43a 4.20b 0.052

Milk, lb/day 83.2b 91.5a 91.5a 91.5a 0.49

ECM2, lb/day 82.9b 89.5a 89.9a 89.9a 0.49

ECM/DMI 1.41b 1.47a 1.47a 1.53a 0.015

Milk fat, % 3.47a 3.28b 3.33ab 3.21b 0.05

Milk protein, % 3.18 3.20 3.20 3.20 0.017

Milk lactose, % 4.84 4.88 4.88 4.88 0.012

Milk SNF3, % 8.80 8.86 8.86 8.86 0.023

Milk fat, lb/day 2.86 2.97 3.01 2.93 0.023

Milk protein, lb/day 2.67b 2.90a 2.90a 2.90a 0.016

Milk lactose, lb/day 4.03b 4.47a 4.47a 4.47a 0.026

Milk SNF, lb/day 7.30b 8.10a 8.07a 8.10a 0.045

Milk urea N, mg/dL 15.14b 15.02b 15.76a 16.01a 0.20

SCC4, × 1000 91 217 139 175 591Dry matter intake.2Energy-corrected milk.3Solids-not-fat.4Somatic cell count.a,b,cRow means not bearing common superscripts differ (P<0.05).

Table 3. Plasma Metabolites


Item 0 20 27.5 35 SEM

Triacylglycerol, mg/dL 14.46 14.39 14.24 14.32 0.61

Urea N, mg/dL 11.61b 12.45a 13.05a 12.96a 0.25

TAAN1, mM 2.48 2.48 2.58 2.57 0.057

Glucose, mg/dL 67.7 68.8 68.3 68.9 0.76

1Total alpha-amino nitrogen.a,bMeans not bearing common superscripts differ (P<0.05).


48

Dairy Day 2000

RELATIONSHIP AMONG CONCENTRATIONS OFMILK UREA NITROGEN AND PLASMA UREA

NITROGEN AND FEEDING TIME

E. E. Ferdinand, J. E. Shirley, M. J. Meyer,A. F. Park, M. J. VanBaale, and E. C. Titgemeyer

Summary

Eight Holstein cows were used to deter-mine the relationship among milk urea nitro-gen (MUN), plasma urea nitrogen (PUN),and feeding time. We first established thatMUN concentrations were similar in concen-tration among quarters by comparing milksamples from each quarter just before milk-ing. In order to determine if collecting asample of milk from a quarter influenced theMUN in samples taken later, samples wereobtained from the right front quarter (RF) at2, 4, 6, and 8 hr after the AM milking andfrom the left front quarter (LF), right rear(RR), and left rear (LR) at 4, 6, and 8 h afterthe AM milking, respectively. The MUN insamples obtained from RF at 4 hr was lower(P<0.01) than corresponding samples takenfrom LF, but samples from RF at 6 and 8 hrdid not differ from corresponding samplesobtained from RR and LR. We concludedthat by 6 hr, the effect of previous milking onMUN concentration disappeared because ofdilution. To determine the influence offeeding time on MUN concentrations, cowswere fed half of their normal PM feeding,injected with oxytocin at the subsequent AMmilking to reduce residual milk, and offeredsurplus feed after the AM milking. Milksamples were collected at 2, 4, 6, 8, 10, and12 hr after feeding from RF, LF, RR, LR,RF, and LF quarters, respectively. Bloodsamples were obtained from the coccygealvein at hourly intervals after feeding with thelast sample collected 12 hr after feeding. TheMUN concentrations at 2, 4, 6, and 8 hr weresimilar. The MUN at 10 hr was similar tothose at 2 and 8 hr, less than that at 4 and 6hr, and greater than that for the 12 hr sam-ple. Concentrations of PUN peaked at 2 hrpostfeeding, then gradually declined through

12 hr postfeeding. The MUN peaked at 6 hrpostfeeding and then declined. Time afterfeeding significantly influenced PUN andMUN concentrations.

(Key Words: MUN, PUN, Feeding Time.)

Introduction

Crude protein in dairy cow diets consistsof ruminally degradable and undegradablefractions. Ruminal microbes utilize degrad-able protein to meet their requirements. Aportion of this degradable protein appears inthe lower tract as microbial protein that canbe digested, absorbed, and utilized by thecow’s body. Undegradable protein passesthrough the rumen and can be digested andabsorbed in the lower tract. The optimalamount of each protein fraction to include inthe diet is influenced by the amount of milkproduced. Milk production dictates theamount of metabolizable protein requiredand influences total feed intake by the cow.Ruminally degradable protein and carbohy-drates in the diet influence the efficiency bywhich rumen microorganisms incorporatedietary rumen degradable protein into micro-bial protein. Generally, the efficiency ofprotein utilization in the rumen decreases asprotein intake increases or the microbialpopulation decreases. One method of evalu-ating protein utilization in the rumen is tomeasure plasma urea nitrogen (PUN), a by-product of ammonia clearance from theblood. This detoxification event occurs inthe liver, where amine groups are bonded toform urea for excretion primarily in theurine. Urea also is recycled back into therumen via the salivary glands or excreted inthe milk. The urea nitrogen in milk (MUN)is correlated highly with that in blood. Thus,


49

MUN provides a convenient method ofestimating PUN.

Feed intake and dietary content ofruminally available protein and rumen solu-ble carbohydrates affect MUN. Changes indietary ingredients that result in more or lessruminally available protein, carbohydrates orboth usually increase or decrease MUN iffeed intake remains relatively constant.Protein not used by the cow contributes tounnecessary feed costs and excretion ofnitrogen into the environment. Concentra-tions of MUN provide a convenient methodto evaluate efficiency of nitrogen utilizationamong diets. The objective of this study wasto determine the influence of feeding time onMUN and PUN concentrations.

Procedures

Eight Holstein cows past peak daily milkproduction were housed and fed in tie-stallfacilities at the Kansas State UniversityDairy Teaching and Research Center,Manhattan. Diets were formulated to meet orexceed NRC (1989) recommendations.Cows were fed a total mixed ration withalfalfa hay and corn silage as the forages andcorn as the cereal grain. Whole cottonseedand mechanically extracted soybean mealwere used as the primary sources of supple-mental fat and protein. Diets were formu-lated to contain .78 Mcal NEL/lb dry matter,17% crude protein, 40% nonfiber carbohy-drate, 6.8% rumen undegradable protein, and10.2% rumen degradable protein on a drymatter basis. Cows were moved into the tie-stall barn 3 days before the beginning ofExperiments 1 and 2 and 10 days beforeExperiment 3. Averages for daily dry mat-ter intake (DMI), crude protein intake (CPI),milk production, energy-corrected milk(ECM), and MUN/lb DMI for the 11-d ex-perimental period are shown in Table 1.Milk samples were analyzed by the Heart ofAmerica DHI Laboratory, Manhattan, KS.

Experiment 1

The objective of this experiment was todetermine whether quarter samples collectedbefore complete milk-out accurately reflect

the MUN concentrations of the total milk inthe mammary glands and whether MUNvalues vary among quarters.

At the AM milking, milk samples wereobtained from each quarter before attachingthe milking machine, and a composite sam-ple was taken from the weigh jar after milk-ing. Milk samples were analyzed for concen-tration of fat, protein, solids-not-fat (SNF),lactose, somatic cell count (SCC), and MUN.

Experiment 2

This experiment was conducted to deter-mine if the process of collecting milk from aquarter influenced the MUN concentrationsin samples obtained from the same quarter at2, 4, 6, and 8 hr after milking. Samplingprocedures consisted of predipping the teat,wiping the dip off, removing three to fivesquirts of milk, and collecting the sample.Milk samples were obtained from the rightfront (RF) quarter 2, 4, 6, and 8 hr after theAM milking. Milk samples were collectedfrom the left front (LF) quarter at 4 hr afterthe AM milking, the right rear (RR) quarter at6 hr after the AM milking, and the left rear(LR) quarter 8 hr after the AM milking.

Experiment 3

Experiment 3 was conducted after resultsof experiments 1 and 2 were known. Theobjective of this experiment was to deter-mine the influence of feeding time on con-centrations of MUN and PUN.

Cows were limit fed the night before theexperiment to encourage intake the nextmorning. At the AM milking, cows wereinjected with 80 IU of oxytocin to removeresidual milk. Cows were fed immediatelyfollowing milking. Milk samples werecollected at 2, 4, 8, 10, and 12 hr after feed-ing from the RF, LF, RR, LR, RF, and LFquarter, respectively. Samples were ana-lyzed for fat, protein, SNF, lactose, SCC, andMUN. Blood samples were collected fromthe coccygeal vein beginning 1 hr after feed-ing and at hourly intervals thereafter, withthe last sample collected 12 hr after feeding.Plasma was separated immediately and


50

frozen until analysis for glucose, total alphaamino nitrogen (TAAN), and PUN.

Results

Experiment 1

The MUN concentrations in milk sam-ples collected immediately before completemilk-out were not different among individualquarters. Urea nitrogen in milk from quar-ters, except the RF, differed (P<0.05) fromthat of the composite sample (Table 2).Percentages of milk fat were similar amongquarters, but were greater in the compositesample (P<0.05) than in the quarter samples.Milk protein percentages among individualquarters did not differ, but were greater insamples from RF and LF than in the compos-ite sample. Percentages of solids-not-fat andlactose in milk were not different amongindividual quarter and composite samples.Fewer (P<0.05) somatic cells were detectedin milk from LF than milk from LR, butcounts were similar among other quartersand the composite (Table 2).

Experiment 2

The MUN concentrations in samplestaken from the RF at 4 hr after completemilk-out and 2 hr after the first sample werelower (P<0.01) than those in samples takenfrom LF at 4 hr (Table 3). Samples obtainedat 6 and 8 hr after milking contained similarconcentrations of MUN among quarterssampled.

Experiment 3

Variation in milk composition over timeafter feeding is shown in Table 4. Milk ureanitrogen peaked at 6 hr postfeeding anddecreased linearly (P<0.01) through 12 hrpostfeeding (Figure 1). Concentrations ofMUN in milk samples obtained at 2, 4, 6,and 8 hr after feeding were numerically, butnot significantly (P>0.05), different. Samplesat 4 and 6 h were different. The 12 hpostfeeding sample contained less (P<0.01)MUN than other samples. Milk fat percent-ages decreased linearly (P<0.01) over time,whereas percentages of milk protein, SNF,

and lactose increased linearly (P<0.01) overtime.

The PUN concentration peaked at 2 hrpostfeeding (15.77 mg/dL), then declined to10.65 mg/dL at 12 hr postfeeding (Figure 1).A linear (P<0.01) relationship was observedbetween PUN and time after feeding; how-ever, PUN concentrations were not differentbetween samples taken 1, 2, 3, and 4 hr afterfeeding. Average PUN and MUN values forthe 12 hr period were similar, 13.4 mg/dLand 13.6 mg/dL, respectively. Plasma glu-cose (Table 5) was lowest (67.43 mg/dL) at3 hr postfeeding, highest at 9 hr postfeeding,similar among other sampling times, and bestdescribed by a quadratic contrast (P<0.01).Plasma TAAN was not influenced by timeafter feeding (Table 5).

Discussion

The primary objective of this study wasto determine the influence of feeding time onconcentrations of MUN and PUN. However,sampling techniques had to be verified be-fore this could be accomplished. First, wehad to establish that MUN concentrationswere similar among individual quarters andthat quarter sample values accurately re-flected values obtained from a milk sampleobtained after complete milk-out of the entireudder (composite sample). Results fromExperiment 1 demonstrated that MUN con-centrations were similar among quarters andthose from all quarters except one differedfrom the composite sample. However, theconcentrations in the three quarter samplesand the composite were within 0.5 mg/dLand would not affect management decisionsconcerning the diet.

The second factor to evaluate waswhether prior sampling influenced the MUNvalue of a later sample. The results fromExperiment 2 indicated that MUN concentra-tions were affected in samples obtained lessthan 4 hr after a quarter was first sampled.The sampling procedure in Experiment 3allowed adequate time (6 hr) between sam-ples from the same quarter for dilution,thereby negating effects of previoussamplings from the quarter.


51

Because most producers obtain milksamples for MUN analysis at either the AMor PM milking, but not both, feeding timebefore each milking may not be the same. Inaddition, when cows are milked by groups,milking time following feeding may varyamong groups. Results from Experiment 3indicate that sampling time after feedingalters MUN and PUN concentrations. Con-centrations of MUN peaked at 6 hr post-feeding and declined through 12 hr post-feeding. Therefore, sampling milk for MUNconcentration, without regard to feedingtime, can affect the results and lead to incor-rect interpretations.

Conclusions

Because time of sampling postfeedingaffects MUN and PUN concentrations, itmust be considered when interpreting resultsand making feeding decisions. According toour results, milk should be sampled at 6 hrpostfeeding in order to obtain the peak MUNconcentration. On the farm, MUN valuesobtained from samples taken at the AM milk-

ing in one test period and the PM milking inthe next test period will vary, if feeding timebefore milking varies. This is important forevaluating responses of cows to diet changesthat may have occurred during the month.Furthermore, MUN concentrations shouldnot be compared among groups when theirfeeding times prior to milking vary. Timeafter feeding also should be considered whensampling for PUN. Samples obtained at 2 hrpostfeeding reflect peak ammonia clearancefrom the blood.

Information gained from this study willassist producers in the interpretation of MUNdata collected from their herd. Diet changesdesigned to increase the efficiency of nitro-gen utilization by the dairy cow depend oncorrect interpretation of data routinely avail-able to the producer.

Acknowledgments

Appreciation is expressed to MikeScheffel and employees at the KSU tie-stallbarn and to Tamie Redding.

Table 1. Average DMI, CPI, Milk, ECM, and MUN/kg DMI

Item Average1 Exps. 1 and 22 Exp. 33

DMI, lb/day 49.65 47.94 56.52

CPI, lb/day 8.45 8.14 9.61

Milk, lb/day 62.79 62.48 65.21

ECM4, lb./day 67.54 65.675 —

MUN/kg DMI — .255 .216

1Average for the 11 d observation period.2Average for day samples taken for Exps. 1 and 2.3Average for day samples taken for Exp. 3.4ECM = energy-corrected milk.5Calculated from composite sample values.6Calculated from 12 hr values.


52

Table 2. Relationship among Quarters with Respect to Milk Composition

Quarter

Item RF LF RR LR Composite

Fat, % 1.54a 1.44a 1.61a 1.52a 3.59b

Protein, $ 3.65ab 3.68a 3.68a 3.63ab 3.60b

SNF, % 9.42a 9.51a 9.48a 9.34a 9.39a

Lactose, % 4.99a 5.04a 5.00a 4.94a 4.98a

SCC, *1000 62.00ab 29.13a 77.38ab 134.63b 63.25ab

MUN, mg/dl 12.25ab 12.48a 12.45a 12.49a 12.06b

a,bMeans within rows sharing different superscript letters differ (P<0.05).

Table 3. Effect of Previous Sampling on MUN Concentration (mg/dL)

Sampling Time, hr

Quarter 2 4 6 8

RF 11.27 12.22a 13.04 13.11

LR – 12.81b – –

RR – – 12.76 –

LR – – – 13.07a,bValues within columns sharing different superscript letters differ (P<0.01).

Table 4. Variation in Milk Composition over Time after Feeding1

Time Postfeeding, hr

Item 2 4 6 8 10 12 Contrast2

Fat, % 7.66 6.37 5.32 4.12 2.27 2.22 linear

Protein, % 3.06 3.26 3.44 3.62 3.93 4.00 linear

SNF, % 8.04 8.23 8.35 8.57 9.03 9.23 linear

Lactose, % 4.22 4.23 4.20 4.25 4.41 4.53 linear

SCC, *1000 956.38 438.88 1135.25 763.25 519.63 369.63 –

MUN, mg/dL 13.65 14.30 14.46 13.94 13.16 12.04 linear1Feeding time began approximately 30 min after AM milking.2P<0.01.


54

Dairy Day 2000

FACTORS AFFECTING DRY MATTER INTAKEBY LACTATING DAIRY COWS

M. J. Brouk and J. F. Smith

Summary

Feed intake is the single most criticalfactor of dairy production, and performanceof dairy cattle can be enhanced or hinderedby environmental factors that affect it. Theseenvironmental factors can by divided intophysical and climatic conditions. On moderndairies, the physical factors may be of moreconcern. Modern facilities provide the cowwith protection from the natural elements.However, these same facilities can enhanceor hinder dry matter intake. Facilities shouldprovide adequate access to feed and water, acomfortable resting area, and adequate pro-tection from the natural elements. Criticalareas of facility design related to feed intakeinclude access to feed and water, stall designand surface, supplemental lighting, ventila-tion, and cow cooling. The total systemshould function to enhance cow comfort andintake. It is important to remember thatchoices made during construction of a facil-ity will affect the performance of animals forthe life of the facility, which is generally 20to 30 yr. Producers, bankers, and consultantstoo often view the additional cost of cowcomfort from the standpoint of initial invest-ment rather than long-term benefit.

(Key Words: Facilities, Cows, Environmen-tal Stress.)

Introduction

One of the keys to success in dairy pro-duction is to design and manage facilities tomaximize the dry matter intake of dairycattle. Intake is impacted by environmentaland management factors. Environmentalconcerns include the physical facilities andclimatic conditions to which the cattle are

exposed. Management factors include feed-ing, grouping, and cow flow patterns thatmay be influenced by facility design. Thegoal of the system should be to provideadequate cow comfort that includes: 1) ade-quate access to feed and water; 2) a clean anddry bed that is comfortable and correctlysized and constructed; 3) acceptable airquality; and 4) adequate protection from thenatural elements.

Access to Feed and Water

4-Row vs 6-Row Barns

One of the critical decisions to make isthe type of freestall barn to build. The mostcommon types are either 4- or 6-row barns.Often the cost per cow or stall is used todetermine which barn should be built. Table1 illustrates the typical dimensions of thebarns, and Table 2 demonstrates the effectsof overcrowding on per-cow space for feedand water. Research indicated that feed bunkspace of less than 8 inches per cow reducedintake and bunk space of 8 to 20 inches percow resulted in mixed results. Even at a100% stocking rate, the 6-row barn offersonly 18 inches of feed-line space per cow.When overcrowding occurs, average feed-line space is reduced significantly. Four-rowbarns, even when stocked at 140% of thestalls, still provide more than 18 inches percow of bunk space. In addition, when wateris provided only at the crossovers, waterspace per cow is reduced by 40% in the 6-row barn compared to 4-row barns. Much ofthe current debate over the effect of 4- and 6-row barns on intake likely is related to pres-ence or absence of management factors thateither reduce on increase the limitations ofaccess to feed and water in 6-row barns.


55

Feed Barrier Design

The use of self-locking stanchions asfeed barriers is currently a debated subject inthe dairy industry. Data reported in theliterature are limited, and conclusions differ.One study (1996) reported that cows re-strained in self-locking stanchions for 4 hrhad milk production and dry matter intakessimilar to those of cows not restrained.Other researchers observed similar results inanother study. However, a third study re-ported similar intake but a 6.4 lb decrease indaily milk production when cows were re-strained during a 4-hr period (9 AM to 1 PM)in the summer. Increases in concentrationsof cortisol also were noted during the sum-mer but not in the spring, indicating a greateramount of stress during the summer. All ofthese studies compared restraining cows for4 hr to no restraint, and all animals werehoused in pens equipped with headlocks.The studies did not compare a neck railbarrier to self-locking stanchions or addressthe effects of training upon headlock accep-tance. Some have interpreted these results tomean that self-locking stanchions reducemilk production and only the neck rail bar-rier should be used. More accurately, theresults indicate that cows should not berestrained for periods of 4 hr during the sum-mer heat. The argument could be made that4 hr of continuous restraint is excessive, andmuch shorter times (1 hr or less) should beadequate for most procedures. These studiesclearly indicate that mismanagement of theself-locking stanchions, not the stanchionsthemselves, resulted in decreased milk pro-duction in only one of three studies but hadno effect on intake in all three studies.

Another study compared lockups to neckrails in a 4-row barn under normal andcrowded (130% of stalls) conditions. Resultsof the short-term study showed a 3 to 5%decrease in dry matter intake when headlockswere used. No differences were observed inmilk production or body condition score. Theovercrowding also reduced the percentage ofcows eating after milking compared to noovercrowding. In this study, use of headlocks

reduced feed intake but did not affect milkproduction.

Freestall Design and Surfaces

Freestall Design

Cows must have stalls that are sizedcorrectly. As early as 1954, research demon-strated increases in milk production whenlarger cows were allowed access to increasedstall sizes. Today, construction costs oftenencourage producers to reduce stall lengthand width. This may reduce cow comfortand production. Cows will use freestalls thatare designed correctly and maintained. Re-fusal of cows to utilize stalls likely is relatedto design or management of the freestallarea. Table 3 provides recommendations forcorrectly sizing the stall. In addition, thestall should be sloped front to back, and acomfortable surface should be provided.

Freestall Surface Materials

Sand is the bedding of choice in manyareas. It provides a comfortable cushion thatconforms to the body of the cow. In addi-tion, its very low content of organic matterreduces risk of mastitis. In many cases, it isreadily available and economical. In someareas, it is not economical, and other produc-ers may choose not to deal with the issue ofseparating the sand from the manure. Be-cause 25 to 50 lb of sand are consumed perstall per day, it should be separated frommanure solids to reduce the solid load on themanure management system. Producerschoosing not to deal with sand bedding oftenchoose from a variety of commercial freestallsurface materials. Research has shown thatwhen given a choice, cows show a prefer-ence for certain materials. Occupancy rang-ed from >50 to <20%. An increase in occu-pancy rate likely was influenced by thecompressibility of the covering. Cows se-lected freestall covers that compressed to agreater degree over those with minimal com-pressibility. Sand and materials that com-press likely will provide greater comfort, asdemonstrated by cow preference.


56

Supplemental Lighting

Lactating Cows

Supplemental lighting has been shown toincrease milk production and feed intake inseveral studies. One study reported a 6%increase in milk production and feed intakewhen cows were exposed to a daily photo-period of 16 hr of light and 8 hr of dark(16L:8:) compared to natural photoperiodsduring the fall and winter months. Medianlight intensities were 462 1ux and 555 1uxfor supplemental and natural photoperiods,respectively. Another study reported a 5%increase in feed intake when proper ventila-tion and lighting were provided. Otherresearchers reported a 3.5% increase withoutbST and 8.9% with bST when photoperiodwas increased from 9.5-14 to 18 hr. Increas-ing daily photoperiod to 16-18 hr of lightincreased feed intake. Additional researchshowed that 24 hr of supplemental lightingdid not result in additional milk productionover 16 hr of light. These studies utilizeddifferent light intensities in different parts ofthe housing area. In modern freestall barns,the intensity varies greatly depending on thelocation of the light source. Thus, additionalresearch is needed to determine the intensi-ties required for different locations withinpens to increase intake.

Another issue with lighting in freestallbarns is milking frequency. Herds milked 3×cannot receive 8 hr of continuous darkness.This is especially true in large freestall barnshousing several milking groups. In thesesituations, the lights may remain on at alltimes to provide lighting for moving cattle toand from the milking parlor. The continuousdarkness requirement of lactating cows maybe 6 hr according to one report. Thus, set-ting milking schedules to accommodate 6 hrof continuous darkness is recommended.The use of low intensity red lights may benecessary in large barns to allow movementof animals without disruption of the darkperiod of other groups.

Dry Cows

Dry cows benefit from a different photo-period than lactating cows. Recent researchshowed that dry cows exposed to short days(8L:16D) produced more milk in the nextlactation than those exposed to long days(16L:8D). An earlier study reported similarresults. Based on these results, dry cowsshould be exposed to short days and thenexposed to long days after calving.

Heat Stress

Effects of Heat Stress

Heat stress reduces feed intake, milkproduction, health, and reproduction of dairycows. Missouri researchers reported thatlactating cows under heat stress decreasedintake by 6 to 16% compared to those inthermal neutral conditions. Arizona workersalso observed that cows cooled during thedry period produced more milk in the subse-quent lactation than cows that were notcooled. The cow environment can be modi-fied to reduce the effects of heat stress byproviding for adequate ventilation and effec-tive cow cooling measures.

Ventilation

Maintaining adequate air quality can beaccomplished easily by taking advantage ofnatural ventilation. Researchers showed thata 4/12 pitch roof with an open ridge resultedin lower afternoon respiration rates of cowsthat a reduced roof pitch or covering theridge. They also observed that eave heightsof 14 ft resulted in lower increases in respira-tion rates than shorter eave heights. Design-ing freestall barns that allow for maximumnatural airflow during the summer will re-duce the effects of heat stress. Open side-walls, open roof ridges, correct sidewallheights, and the absence of buildings ornatural features that reduce airflow increasenatural airflow. During winter, it is neces-sary to allow adequate ventilation to main-tain air quality while providing adequateprotection from cold stress.


57

Another ventilation consideration is thewidth of the barn. Six-row barns are typicallywider than 4-row barns. This additional widthreduces natural ventilation. Summer ventila-tion rates are reduced 37% in 6-row barnscompared to 4-row barns. In hot and humidclimates, barn choice increases heat stress,resulting in lower feed intake and milk pro-duction.

Cow Cooling

During periods of heat stress, it is neces-sary to reduce cow stress by increasing air-flow and installing sprinkler systems. Thecritical areas to cool are the milking parlor,holding pen, and housing area. First, theseareas should provide adequate shade. Barnsbuilt with a north-south orientation allowmorning and afternoon sun to enter the stallsand feeding areas and may not adequatelyprotect the cows. Second, as temperaturesincrease, cows depend upon evaporativecooling to maintain core temperature. Theuse of sprinkler and fan systems to effectivelywet and dry the cows will increase heat loss.

The holding pen should be cooled withfans and sprinkler systems, and an exit lanesprinkler system may be beneficial in warmer.

climates. Holding pen time should not exceed1 hr. Fans should move 1,000 sq ft/min percow. Most 30- and 36-inch fans will movebetween 10,000 and 12,000 sq ft/min per fan.If one fan is installed per 10 cows or 150 sq ft,adequate ventilation should be provided. Ifthe holding pen is less than 24 ft wide with 8-10 ft sidewall openings, fans can be installedon 6- to 8-ft centers along the sidewalls. Forholding pens wider than 24 ft, fans aremounted perpendicular to the cow flow. Fansare spaced 6- to 8-ft apart and in rows spacedeither 20 to 30 ft apart (36-inch fans) or 30 to40 ft apart (48-in fan). In addition to the fans,a sprinkling system should deliver .03 galwater per sq ft of area. Cycle times generallyare set at 2 min on and 12 min off.

Heat abatement measures in freestallhousing should include feed-line sprinklersand fans to increase air movement. Sprinkl-ing systems should deliver water similar to theholding pen system, except they should wetonly the area occupied when the cow is at thefeed bunk. The hair coat of the cow shouldbecome wet and then be allowed to dry priorto the beginning of the next wetting cycle.Fans can be installed over the feed-line toprovide additional airflow and increase evapo-ration rate.

Table 1. Average Pen Dimensions, Stalls, Cows, and Allotted Space per Animal in4-Row and 6-Row Barns

Per Cow

BarnStyle

PenWidth

PenLength

Stallper Pen

Cowsper Pen Area

FeedlineSpace

WaterSpace

– ft – – ft – – no. – – no. – – sq ft – - inches - - inches -

4-Row 39 240 100 100 94 29 2.4

6-Row 47 240 160 160 71 18 1.5

2-Row 39 240 100 100 94 29 2.4

3-Row 47 240 160 160 71 18 1.5

Adapted from Smith et al., 2000. Relocation and Expansion for Dairy Producers. KansasCooperative Extension Service, MF2424, page 8.


58

Table 2. Effect of Stocking Rate on Space per Cow for Area, Feed and Water in 4- and6-Row Barns

Area, Feedline Space, Water Space,

sq ft/cow linear inches/cow linear inches/cow

Stocking Rate, % 4-Row 6-Row 4-Row 6-Row 4-Row 6-Row

100 28.5 21.3 29 18 2.4 1.5

110 25.9 19.4 26 16 2.2 1.4

120 23.8 17.8 24 15 2.0 1.3

130 21.9 16.4 22 14 1.9 1.1

140 20.4 15.2 21 13 1.7 1.1

Adapted from Smith et al., 2000. Relocation and Expansion for Dairy Producers. KansasCooperative Extension Service, MF2424, page 8.

Table 3. Freestall Dimensions for Cows of Various Body Weights

Body WeightFree Stall

Width Side LungeForwardLungea

Neck RailHeightabove

Stall Bed

Neck Rail andBrisket BoardBed, Distance

from Alley Side ofCurb

– lb – – inches – – inches – – inches – – inches – – inches --

800-1,200 42 to 44 78 90 to 96 37 62

1,200- 1,500 44 to 48 84 96 to 102 40 66

Over 1,500 48 to 52 90 102 to 108 42 71aAn additional 12 to 18 inches in stall length are required to allow the cow to thrust her

head forward during the lunge process.Adapted from Dairy Freestall Housing and Equipment,1997. 6th Edition. Midwest Plan

Service, Publication MWPS7, page 2. Iowa State University, Ames.


1Department of Biological and Agricultural Engineering.

59

Dairy Day 2000

KEEPING COWS COOL

J. F. Smith, J. P. Harner 1, and M. J. Brouk

Summary

Heat stress occurs when a dairy cow’sinternal heat load is greater than her capacityto lose unwanted heat to the environment.Effects of heat stress include: increasedrespiration rate, increased water intake, in-creased sweating, decreased dry matter in-take, slower rate of feed passage, decreasedblood flow to internal organs, decreased milkproduction, and poor reproductive perfor-mance. Lower milk production and repro-ductive performance cause economic lossesto dairy producers. The ordered priorities forreducing heat are: increasing water availabil-ity; providing shade in the housing areas(both dry and lactating cows) and holdingpen; reducing walking distance to the parlor;reducing time in the holding pen; improvingholding pen ventilation and freestall ventila-tion; adding cooling for the holding pen andexit lane; cooling close-up cows (3 wk beforecalving); cooling housing for fresh and early-lactation cows; and cooling housing for mid-and late-lactation cows.

(Key Words: Heat Stress, Cooling Tech-niques.)

Water Availability

Providing access to water during heatstress should be the first step. Lactating dairycattle typically require between 35 and 45gallons of water per day. Studies done inclimatic chambers indicate that water needsincrease 1.2 to 2 times when cows are underheat stress. A water system needs to be

designed to meet both peak demand anddaily needs of the dairy. Making water avail-able to cows leaving the milking parlor willincrease water intake by cows during heatstress. Access to an 8-ft water trough isadequate for milking parlors with #25 stallsper side. When using dry-lot housing, werecommend placing water troughs at twolocations using the following formula tocalculate the required tank perimeter. Groupsize × 0.15 × 2 = tank perimeter in feet. Infreestall housing, one waterer or 2 ft of tankperimeter is adequate for every 15 to 20cows. An ideal situation would be to havewater available at every crossover betweenfeed and resting areas. A minimum of twowatering locations per pen is needed.

Shades

Providing shade in housing areas and theholding pen is the second step. Cows housedin drylot or pasture situations should beprovided with solid shade. Florida research-ers found that cows housed with shade pro-duced more milk and had greater conceptionrates than nonshaded cows. Natural shadingprovided by trees is effective, but most oftenshades are constructed from solid steel oraluminum. Providing 38 to 48 sq ft of solidshade per mature dairy cow is adequate toreduce solar radiation. Shades should beconstructed at a height of a least 14 ft with anorth-south orientation to prevent wet areasfrom developing under them. More porousmaterials such as shade cloth or snow fenceare not as effective as solid shades.


60

Methods to Cool Cows

Several trials have evaluated differentcooling systems in a wide variety of climates.Everything from high-pressure misters tolow- pressure sprinklers or soakers have beenused to apply water to cows along with fansystems to aid in the evaporation of water offthe cow’s back or out of the air around thecow. As humidity increases in the environ-ment, the ability to evaporate waterdecreases. In general, low-pressure sprinkleror soaker systems to wet cows along withfans can be used in any climate to cool cows.We can witness the effectiveness of thesesystems by visiting the local pool on a hotwindy day. The children will leave the pooland become cold as the water evaporates offtheir skin. Just watch these children developgoose bumps as they search for their towels.Once they dry off, they become warm andjump back in the pool to start the same cycleagain. The same technique is used in coolingdairy cattle by wetting cows intermittently.Remember that high-pressure systems coolthe air around the cow and work best in veryarid climates. When we combine low-pres-sure and high-pressure systems, we run therisk of reducing the ability to evaporatemoisture off the cows’ back. Unless you areproducing milk in an arid climate, a low-pressure system is probably the most eco-nomical and practical way to cool cows.

Holding Pen and Exit Lane Cooling

The holding pen is where dairy cowsprobably experience the most heat stress.Arizona researchers concluded that whencows were cooled in the holding pen, milkproduction was increased 1.7 pounds per dayduring the summer. To make this improve-ment, low-volume sprinklers are used to wetcows, and fans are used to hasten evaporationof the water off their backs. Fans should beoperated continuously providing a minimumof 1,000 cu ft per cow. Fans should bemounted overhead at a 30° angle from verti-cal, so that the air will blow downward. Fansof 36- to 48-inch diameter used are mostcommonly. Fans typically are spaced 6 to 8ft side-to-side. The distances between rowsof fans are 20 ft for 30- and 36-inch fans and

40 ft for 48-inch fans. Water can be sprayedonto the cows using a PVC grid of 360°nozzles. Water is applied for 1 min every 6min.

Cows can be cooled as they exit the parlorto provide an additional 15 to 25 min ofcooling per milking. Typically, three to fournozzles are installed in the exit lane, with adelivery of approximately 8 gallons of waterper minute at 35 to 40 PSI. The nozzles areturned on and off with an electric eye orwand switch as the cow passes under thenozzles. If properly installed, nozzles willwet the top and sides of the cow, but theudder will remain dry so water does not washoff postmilking teat dips.

Freestalls

Freestall housing should be constructed toprovide good natural ventilation. Sidewallsshould be 14 ft high to increase the volume ofair in the housing area. They should be 75 to100% open. Fresh air should be introduced atthe cow’s level. Curtains on the sides of free-stall barns allow greater flexibility in control-ling ventilation. Because warm air rises,steeper sloped roofs provide upward flow ofwarm air. However, roofs with slopes steeperthan a 6/12 pitch prevent incoming air fromdropping into the area occupied by the cows.Roofs with slopes less than 4/12 may causecondensation and higher internal tempera-tures in the summer. Roof slopes for freestallhousing should range from 4/12 to 4/16.Providing openings in end walls and alleydoors improves summer ventilation. Gablebuildings should have a continuous ridgeopening to allow warm air to escape. Theridge opening should be 2 inches for each 10ft of building width. The distance betweennaturally ventilated buildings should be aminimum of 1.5 to 2 times the buildingwidth.

Adding fans and a sprinkler system pro-vides additional cooling in freestall areas.Freestall bedding must not become wet.Typically, a sprinkler system or soaker sys-tem can be located over the feed-line lock-ups. Fans can be used over the freestalls,lockups, or both to increase evaporation of


61

water off the cow’s back. Water is appliedfor 3 min every 15 min. These spray and fansystems can be turned on and off with athermostat set at 70 to 75°F.

Which Groups of Cows Do I Cool First?

A commonly asked question is whichcows should be cooled first? The short an-swer is that all lactating and dry cows shouldbe cooled, if possible. All lactating cowswill respond to cooling during heat stress.With a limited budget, a choice of whichgroup of cows to cool is required. The firstgroup to cool should be the close-up cows.Dry matter intake before calving is critical toensure that the upcoming lactation is suc-cessful. Cows consume less dry matterduring heat stress. The second group to becooled should be the fresh and early-lactationcows. These cows are approaching theirpeak daily milk production. For every poundof peak daily milk yield that is lost, 250pounds of milk production will be lost overthe entire lactation. It is not uncommon forproducers in Kansas to lose 10 pounds of

peak milk yield during heat stress when cowsare not cooled. That is equivalent to 2500pounds of milk over the lactation. Onceearly-lactation cows have been cooled, themid- and late-lactation cows should becooled.

Where Do I Start?

With a limited budget, start with step 1and proceed through step 9: 1) increasingwater availability; 2) providing shade inhousing areas of dry and lactating cows andin the holding pen; 3) reducing walkingdistances to the parlor; 4) reducing time inthe holding pen; 5) improving ventilation inthe holding pen and freestall area; 6) addingcooling systems in the holding pen and itsexit lanes; 7) cooling close-up cows during 3wk before expected calving date; 8) coolingfresh cows and those in early lactation; and9) cooling mid- and late-lactation cows.Starting with the basics and working overtime to cool all the cows on your dairy willpay big dividends. Good luck keeping yourcows cool during summer!


1The authors are indebted to Duane Meier (Meier Dairy, Palmer, KS) and SteveOhlde (Ohlde’s Dairy, Linn, KS) for the use of their cattle in conducting these studies.

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Dairy Day 2000

ANESTRUS IN LACTATING DAIRY COWS BEFORE OVULATION SYNCHRONIZATION

J. S. Stevenson, J. A. Cartmill,S. E. Zarkouny, and B. A. Hensley 1

Summary

The incidence of anestrus in dairy cattleprior to first inseminations carried out after aminimum of 60 days postpartum ranged from4 to 58% in first-lactation cows and 14 to50% in older cows. Dairy cows with moredays in milk, older than 2 years, and in betterbody condition (probably reflective of greaterpostpartum dry matter intakes) were morelikely to cycle than thinner cows. Cows thatwere not cycling before the first week ofinsemination conceived at lower rates andtook longer to become pregnant.

(Key Words: Body Condition, Cows, An-estrus.)

Introduction

Most mammals naturally undergo avariable period of anestrus following parturi-tion. This period is referred to as alactational or postpartum anestrus. Variousfactors contribute to the duration of thisperiod, including age or lactation number,dry matter intake, body condition, milkingfrequency, and overall health. The mostprolonged intervals to normal postpartumovarian activity and onset of estrous cyclesare observed in suckled cows, because multi-ple suckling bouts and continued cow-calfinteractions prevent reestablishment of nec-essary pituitary hormone secretions (i.e.,luteinizing hormone) to support follicularmaturation.

Most studies have indicated that cowsmilked twice daily generally ovulate for thefirst time after calving sometime between 15and 30 days in milk. As frequency of milk-ing increases, the interval to first ovulationmay increase slightly, but in all cases, theinterval to first estrus is more prolonged thanthe interval to first ovulation. A high per-centage of cows fail to show any sexualbehavior (estrus) prior to first ovulations, butnearly all cows display estrus by the thirdovulation.

Because of the preceding knowledgeabout dairy cows, most have consideredanestrus not to be a limiting factor in achiev-ing pregnancies. However, in more recenttimes, where cows are milked 3× daily andbST is used nearly universally, cows aremore likely to carry less body condition intothe dry period. Therefore, the potential existsfor cows to experience more prolonged peri-ods of anestrus.

Nutrients are used by cows according toan established priority. The first priority ismaintenance of essential body functions topreserve life. Once that maintenance re-quirement is met, remaining nutrients accom-modate growth. Finally, lactation and theinitiation of estrous cycles are supported.Because older cows have no growthrequirement, nutrients are more likely to beavailable for milk synthesis and estrous cycleinitiation. Because of this priority system,young, growing cows generally produce lessmilk and are anestrous longer after calving.As a consequence, one might expect these


63

factors to influence the ability of the cows toinitiate estrous cycles early after calving.

The objective of this collection of studieswas to determine the incidence of anestrus indairy cows prior to initiating various pro-grammed breeding protocols that attempt tosynchronize ovulation before first artificialinseminations.

Procedures

In the last 3 years, we have studied morethan 1300 dairy cows on three dairy farms.As part of those studies, we have estimatedthe cycling status of these cows based onblood samples that were collected beforesynchronization of estrus, ovulation, or both.Blood samples were collected at least twicebetween 0 and 19 d before PGF2" was admin-istered on Monday of the insemination weekand later assayed for concentrations of pro-gesterone. This period corresponded to 40 to83 days in milk when body scores also weremeasured (1 = thin and 5 = fat).

Cows were classified as anestrous whenserum concentrations of progesterone were<1 ng/ml in all samples collected prior to theinsemination week. If any one of severalblood samples collected contained progester-one >1 ng/ml, these cows were considered tohave initiated estrous cycles prior to theinsemination week.


Table 1 summarizes the results of thesestudies. Two studies were conducted in non-summer months, and the third during a hotsummer in Kansas (1998). One of theseherds was milking 3× daily, and all herds’rolling DHI averages for milk exceeded20,000 lb.

In the first study of 678 cows, the averagepercentage of cows cycling before timed AI(TAI) was 82% (Table 1). In the first-lacta-tion, 2-year-old cows, cycling percentage waslower in one herd than in the second herd,whereas no difference in cycling percentages

were detected between herds for older cows.Body condition scores assessed at time ofblood sampling averaged 2.3. Cows in betterbody condition were more likely to be cy-cling than thinner cows. Cows with moredays in milk at the blood-sampling times alsowere more likely to be cycling.

In the second study of 251 cows in oneherd where cows were milked 3× daily, thepercentage of cows cycling was less at 44%(Table 1). Again, body condition averagedabout 2.3. Younger and thinner cows wereless likely to be cycling. In fact, as bodycondition increased by 0.5 units, the percent-age of cows cycling increased by 24%. Milkyield (150-d energy-corrected milk) had noinfluence on cycling percentages.

In the last study of 385 cows in threeherds during the summer, the percentage ofcows cycling was 84% (Table 1). In thisstudy, lactation number did not affectcyclicity, but body condition (average of 2.4)was very important. For every 0.5 unit in-crease in body condition for cows in thestudy, cyclicity increased by 7.2%.

Subsequent first-service pregnancy rates(measured at days 27-29 after insemination)in dairy cows that were either cycling oranestrous prior to the insemination week aresummarized in Table 2. In nearly everycomparison, pregnancy rates were numeri-cally less in those cows that were anestrousprior to insemination. The exceptions werethose anestrous cows treated with progester-one (via an intravaginal progesterone-releas-ing device or CIDR-B) and anestrous cowstreated with the Ovsynch protocol during thesummer.

The important point learned from thesestudies was that cows not cycling by the endof the volunteer waiting period conceived atlesser rates and took longer to eventually getback in calf (data not shown). In each case,body condition was a very important predic-tor of when cows began estrous cycles aftercalving.


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Table 1. Estimates of Cycling Status of Lactating Dairy Cows Producing More than20,000 lb of Milk before the Onset of First AI

No. ofCows

Days in Milk when BloodSampling Occurred

Lactation Number

Season Herd 1 2+

----- % cycling -----

Not summer 12

284394

48-6840-60

8872

8687

Not summer 1 251 47-67 42 50

Summer123

66198121

63-8357-7756-76

968377

858786

Table 2. First-Service Pregnancy Rates of Lactating Dairy Cows Based on TheirCycling Status Prior to First Insemination

Cycling Status

Season Treatments No Yes

----- % pregnancy rates (no. of cows) -----

Not summer1 OvsynchOvsynch + CIDR

28 (54)62 (50)

47 (36)54 (41)

Not summer2Ovsynch

PGF + Ovsynch2 × PGF

22 (37)33 (47)20 (44)

36 (189)43 (186)37 (197)

Summer3 OvsynchSelect Synch

36 (31)13 (31)

33 (176)19 (187)

1Ovsynch = injections of GnRH 7 days before and 48 hr after PGF2". Ovsynch + CIDR(Ovsynch + a progesterone-releasing device placed in the vagina for 7 days beginning at thefirst GnRH injection and removed when PGF2" was injected. In both cases, one AI wasadministered at 16 to 20 hr after the second GnRH injection.

2Ovsynch = as described above. PGF + Ovsynch = one injection of PGF2" given 12 daysbefore the Ovsynch protocol. 2 × PGF = injections of PGF2" given 12 days apart and oneinjection of GnRH given 48 hr after the second PGF2" injection. In all cases, one AI wasadministered at 16 to 20 hr after the second GnRH injection.

3Ovsynch = as described above. Select Synch = injection of GnRH 7 days before PGF2" andcows inseminated after detected estrus.


1The authors are indebted to Duane Meier (Meier Dairy, Palmer, KS) and SteveOhlde (Ohlde’s Dairy, Linn, KS) for the use of their cattle in conducting these studies.

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Dairy Day 2000

EMBRYO SURVIVAL IN LACTATING DAIRY COWS

J. S. Stevenson, J. A. Cartmill,S. E. Zarkouny, and B. A. Hensley 1

Summary

Rates of embryo survival in lactatingdairy cows were assessed in three separatestudies. Based on pregnancy diagnoses 27 to29 days after timed inseminations, survival todays 40 to 50 or day 57, depending on thestudy, varied from 9 to 88% in cows thatwere not cycling before insemination com-pared to 57 to 90% in cows that were cycling.Previously anestrous cows had lower rates ofsurvival. In one study, supplementing cowswith progesterone before insemination im-proved embryo survival.

(Key Words: Embryo Survival, Cows, FirstAI.)

Introduction

Reproductive failure of cows results infinancial liabilities to dairy producers. Theseliabilities include greater breeding costs,greater involuntary culling rates, and in-creased maintenance costs. Embryo and fetaldeaths following insemination are majorcomponents of these losses.

Previous research indicates that about90% of the eggs are fertilized, and averagecalving rates are 55% following single in-seminations. Based on those estimates, therate of embryonic and fetal mortality is 38%.Of this total loss, 70 to 80% probably issustained between days 8 and 16 after AI,10% between days 16 and 42, and 5 to 8%between day 42 and term. In so-called

“repeat breeders,” fertilization and embryolosses are even greater.

Current studies of pregnancy losses indairy cows located in Ireland, where cowsproduce about 50% as much milk as U.S.dairy cows, seem to substantiate the lossescited above. Based on one U.S. study ofdairy cows annually producing in excess of24,000 lb of milk, pregnancy losses are muchgreater. These losses likely are related to thegreater milk-producing capacity of our cows.Of pregnancies diagnosed on day 28 after AI(using transrectal ultrasonography), survivalrates of the pregnancies were 89.5% to day42; 83.2% to day 56; 81.5% to day 70; and79.8% to day 98.

The purpose of the current survey of threeKansas dairy farms was to estimate theamount of pregnancy loss that was occurringafter first AI services.

Procedures

Three studies were conducted in whichfirst postpartum inseminations wereprogrammed with various ovulation synchro-nization protocols.

Study 1 consisted of cows inseminatedafter the Ovsynch protocol (injections ofGnRH given 7 days before and 48 hr afterPGF2" with timed AI [TAI] 16 to 20 hr afterthe second GnRH injection) compared tocows inseminated after the Select Synchprotocol (injection of GnRH 7 days beforePGF2" and inseminations performed after


66

visually detected estrus). This study wasconducted during the summer of 1998 on twodairy farms and during the summers of 1998and 1999 on a third dairy farm. Pregnancywas diagnosed once between 27 to 29 daysafter AI (transrectal ultrasonography) andreconfirmed by palpation between 40 and 50days.

Study 2 (winter and spring of 1997-1998)consisted of cows inseminated after theOvsynch protocol compared to those insemi-nated after the same protocol but with aCIDR (controlled internal drug release: aprogesterone-releasing device) insertedintravaginally at the time of the first GnRHinjection and removed 7 days later whenPGF2" was administered (Ovsynch + CIDR).Inseminations were carried out 16 to 20 hrafter the second GnRH injection. Pregnancywas diagnosed (transrectal ultrasound) on day29 after TAI and again at day 57.

Study 3 (fall, winter, and spring of 1997-1999) consisted of cows inseminated after theOvsynch protocol compared to: 1) thoseinseminated after the same protocol but withone injection of PGF2" 12 days before thecows received the first GnRH injection of theOvsynch protocol (PG + Ovsynch), and 2)those inseminated after having received twoinjections of PGF2" 12 days apart and oneGnRH injection 48 hr after the last of twoPGF2" injections (2×PG12). In all threeprotocols, cows were inseminated 16 to 20 hrafter the second or only GnRH injection.Pregnancy was diagnosed once at 27 to 29days after AI (transrectal ultrasound) andreconfirmed by palpation between 40 and 50days.


Embryo survival for Study 1 is summa-rized in Table 1. Of cows diagnosed preg-nant by ultrasound on days 27 to 29, fewer(P=0.07) embryos survived to days 40 to 50

(palpated pregnancy diagnosis) after theOvsynch than Select Synch protocols. Cowsidentified to be not cycling before the onsetof the breeding protocols had less (P<0.05)embryo survival than cycling cows. Theseresults may indicate that noncycling cows inboth treatments were induced successfully toovulate and subsequently conceive, but had adecreased ability to maintain pregnancybeyond 27 to 29 days.

In Study 2, embryo survival was en-hanced (P<0.05) greatly by treatment of cowswith progesterone (Table 1) in conjunctionwith the Ovsynch protocol. In this study,embryo survival was not affected by previouscycling status.

Embryo survival in Study 3 is illustratedin Table 1. Rates of embryo survival tended(P=0.09) to be affected by an interaction oftreatment and cycling status. Although cy-cling cows had numerically better embryosurvival in all treatments, survival in the2×PG12, noncycling cows apparently wasreduced. These results indicate that thenoncycling cows possibly benefitted from thefirst GnRH injection given 10 days beforeTAI in both groups treated with the Ovsynchprotocol.

The average survival rates were 53% incows not cycling before insemination and77% for cows that were cycling. These areconsiderably less than those reported else-where (approximately 83%). It is alarming tosee such losses occurring in Holstein cowsafter they have conceived. Causes for theselosses are unknown but may include insuffi-cient energy, too much crude protein (partic-ularly rumen-degradable protein that elevatesblood and milk urea nitrogen and ammonia),and(or) insufficient luteal function (reducedconcentrations of progesterone in bloodserum of cows). We plan to investigatefurther if insufficient progesterone is a pri-mary cause for embryo losses in lactatingdairy cows.


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Table 1. Embryo Survival after d 27 to 29 of Pregnancy in Lactating Dairy Cows

Cycling Status1 Probabilities

Treatments No Yes Treatment Cycling T×C

% embryo survival5(no. of pregnancies

diagnosed on days 27-29)

Study 12

Ovsynch Select Synch

20 (15)9 (11)

50 ( 4)

63 ( 95) 57 ( 58)73 ( 37)

0.07 0.03 0.44

Study 23

Ovsynch Ovsynch + CIDR

61 (49)50 (16)67 (33)

78 ( 37) 63 ( 16) 90 ( 21)

0.02 0.20 0.56

Study 34

Ovsynch PG + Ovsynch 2×PG12

67 (33)88 ( 8) 69 (16)44 ( 9)

73 (223)70 ( 70)76 ( 80)74 ( 73)

0.11 0.47 0.09

1Cows with elevated concentrations of progesterone (>1 ng/ml) in blood serum samplescollected before insemination were cycling and those with progesterone <1 ng/ml wereanestrus.

2Ovsynch = injections of GnRH 7 days before and 48 hr after PGF2". Inseminations wereconducted 16 to 20 hr after the second GnRH injection. Select Synch = injection of GnRH 7days before PGF2" and cows inseminated after detected estrus.

3Ovsynch = as described above. Ovsynch + CIDR (Ovsynch + a progesterone-releasingdevice placed in the vagina for 7 days beginning at the first GnRH injection and removed whenPGF2" was injected. In both cases, one AI was administered at 16 to 20 hr after the secondGnRH injection.

4Ovsynch = as described above. PG + Ovsynch = one injection of PGF2" given 12 daysbefore the Ovsynch protocol. 2×PG12 = injections of PGF2" given 12 days apart and oneinjection of GnRH given 48 hr after the second PGF2" injection. In all cases, one AI wasadministered at 16 to 20 hr after the second GnRH injection.

5Embryo survival after days 27 to 29 (via ultrasonography) until cows were palpated forpregnancy diagnosis between 40 and 50 days. Survival in Study 2 (Ovsynch vs Ovsynch +CIDR) represent those from day 29 to day 57 (via ultrasonography).


68

Dairy Day 2000

INDEX OF KEY WORDS

Indexer’s note: The numbers indicate the first pages of each article that uses the listed keyword.

Anestrus . . . . . . . . . . . . . . . . . . . . . 62

Bacteria . . . . . . . . . . . . . . . . . . . . . . . 4

Bedding . . . . . . . . . . . . . . . . . . . . . . 17

Blood Protein . . . . . . . . . . . . . . . . . . 23

Body Condition . . . . . . . . . . . . . . . . 62

Calves . . . . . . . . . . . . . . . . . . . . 21, 23

Colostrum . . . . . . . . . . . . . . . . . . . . 23

Cooling Cows . . . . . . . . . . . . . . . . . 29

Cooling Techniques . . . . . . . . . . . . . 59

Corn Silage . . . . . . . . . . . . . . . . . . . 36

Cows . . . . . . . . . . . . . . . . . . 54, 62, 65

Dairy . . . . . . . . . . . . . . . . . . . . . . . . 13

Economics . . . . . . . . . . . . . . . . . . . . 29

Efficiency . . . . . . . . . . . . . . . . . . . . . 33

Embryo Survival . . . . . . . . . . . . . . . . 65

Environmental Stress . . . . . . . . . . . . 54

Facilities . . . . . . . . . . . . . . . . . . . . . . 54

Feeding Time . . . . . . . . . . . . . . . . . . 48

First AI . . . . . . . . . . . . . . . . . . . . . . 65

Flush . . . . . . . . . . . . . . . . . . . . . . . . 17

Hairy Heel Warts . . . . . . . . . . . . . . . 25

Health . . . . . . . . . . . . . . . . . . . . . . . 33

Heat Stress . . . . . . . . . . . . . . . . 29, 59

Heifers . . . . . . . . . . . . . . . . . . . . . . . 21

Incoming Tests . . . . . . . . . . . . . . . . . . 1

Intake . . . . . . . . . . . . . . . . . . . . . . . 39

Ionophore . . . . . . . . . . . . . . . . . . . . 33

Lactating Cows . . . . . . . . . . . . . . . . 44

Lagoons . . . . . . . . . . . . . . . . . . . . . . 13

Manure . . . . . . . . . . . . . . . . . . . 13, 17

Mastitis . . . . . . . . . . . . . . . . . . . . . . . 4

Milk Quality . . . . . . . . . . . . . . . . . . . . 4

Milk Production . . . . . . . . . . . . . . . . . 4

Milk Yield . . . . . . . . . . . . . . . . . . . . 44

Morbidity . . . . . . . . . . . . . . . . . . . . . 23

MUN . . . . . . . . . . . . . . . . . . . . . . . 48

Nonantibiotic . . . . . . . . . . . . . . . . . . 25

Nutrients . . . . . . . . . . . . . . . . . . . . . 13

Nutritive Value . . . . . . . . . . . . . . . . . 36

PUN . . . . . . . . . . . . . . . . . . . . . . . . 48

Quality . . . . . . . . . . . . . . . . . . . . . . . . 1

Raw Milk . . . . . . . . . . . . . . . . . . . . . . 1

Salmonella dublin . . . . . . . . . . . . . . 21

Sand . . . . . . . . . . . . . . . . . . . . . 13, 17

Silage Storage . . . . . . . . . . . . . . . . . . 9

Silage . . . . . . . . . . . . . . . . . . . . . . . . . 9

Surface Spoilage . . . . . . . . . . . . . . . 36

Therapy . . . . . . . . . . . . . . . . . . . . . . 25

Transition Cow . . . . . . . . . . . . . . . . 39

Wet Corn Gluten Feed . . . . . . . . 39, 44


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Dairy Day 2000

ACKNOWLEDGMENTS

Appreciation is expressed to the following organizations for their support of dairy teaching,research, and extension at Kansas State University:

Alfa-Laval, Kansas City, MO

Dairy Farmers of America, Kansas City, MO

Eli Lilly and Co., Greenfield, IN

Grain State Soya, West Point, NE

Heart of America Dairy Herd Improvement

Association (DHIA), Manhattan, KS

Hiland Dairy, Manhattan, KS

Hoffmann-LaRoche, Nutley, NJ

Hubbard Feed, Mankato, MN

Interag, Hamilton, New Zealand

Intervet, Inc., Millsboro, DE

Iowa Limestone, Des Moines, IA

Kansas Agricultural Experiment Station,

Manhattan, KS

Kansas Artificial Breeding Service Unit

(KABSU), Manhattan, KS

Kansas Dairy Association, Wamego, KS

Kansas Dairy Commission, Wamego, KS

Kansas Farm Management Association,

Manhattan, KS

Kansas Grain Sorghum Commission, Topeka,

KS

Meier Dairy of Palmer, Inc., Palmer, KS

Merial Limited, Iselin, NJ

Miley Equipment Co., Emporia, KS

Minnesota Corn Processors, Marshall, MN

Monsanto Company, St. Louis, MO

Moorman Feed, Quincy, IL

Ohlde’s Dairy, Linn, KS

Pharmacia & Upjohn, Kalamazoo, MI

Pioneer Hi-bred International, Inc., Des

Moines, IA

Prestressed Concrete, Inc., Newton, KS

Rota-Mix, Dodge City, KS

Select Sires, Plain City, OH

West Central Coop, Ralston, IA

Western Dairy Management Conference

West Agro, Inc., Kansas City, KS

Cimarron Dairy, Cimarron, KS

Appreciation is expressed to Eileen Schofield, Senior Editor of the Kansas Agricultural Experiment

Station for editing; to Valerie Stillwell and Tamie Redding for typing the contents of this publication;

and to Fred Anderson for the cover design. The Department of Agricultural Economics, College of

Agriculture; the Department of Biological and Agricultural Engineering, College of Engineering; and

the Food Animal Health and Management Center, College of Veterinary Medicine at Kansas State

University are recognized for their cooperation and contribution to our dairy research program.

Contribution No. 01-166-S from the Kansas Agricultural Experiment Station, Kansas State

University, Manhattan 66506. Trade names are used to identify products. No endorsement is

intended, nor is any criticism implied of similar products not named.


70

Dairy Day 2000

BIOLOGICAL VARIABILITY AND CHANCES OF ERROR

Variability among individual animals in an experiment leads to problems in interpreting theresults. Although the cattle on treatment X may have produced more milk than those ontreatment Y, variability within treatments may indicate that the differences in production betweenX and Y were not the result of the treatment alone. Statistical analysis allows us to calculate theprobability that such differences are from treatment rather than from chance.

In some of the articles herein, you will see the notation "P<.05". That means theprobability of the differences resulting from chance is less than 5%. If two averages are said tobe "significantly different", the probability is less than 5% that the difference is from chance or theprobability exceeds 95% that the difference resulted from the treatment applied.

Some papers report correlations or measures of the relationship between traits. Therelationship may be positive (both traits tend to get larger or smaller together) or negative (as onetrait gets larger, the other gets smaller). A perfect correlation is one (+1 or -1). If there is norelationship, the correlation is zero.

In other papers, you may see an average given as 2.5 ± .1. The 2.5 is the average; .1 isthe "standard error". The standard error is calculated to be 68% certain that the real average(with unlimited number of animals) would fall within one standard error from the average, in thiscase between 2.4 and 2.6.

Using many animals per treatment, replicating treatments several times, and using uniformanimals increase the probability of finding real differences when they exist. Statistical analysisallows more valid interpretation of the results, regardless of the number of animals. In all theresearch reported herein, statistical analyses are included to increase the confidence you canplace in the results.

Contents of this publication may be freely reproduced for educational purposes. Allother rights reserved. In each case, give credit to the author(s), name of work,Kansas State University, and the date the work was published.


T h e L i v e s t o c k & M e a t I n d u s t r y F o u n d a t i o n , I n c .

Officers and Directors

Bill AmsteinPresident

Don SmithVice President

Harland PriddleSecretary

Kenneth KnightTreasurer

Dee W. JamesExecutive Vice President

Don L. GoodDirector of Development

Raymond Adams. Jr.Dell M. AllenRichard ChaseMax DeetsHenry GardinerFred C. GermannSam HandsKathy PattonMikel StoutDuane Walker

Royal Board MembersHarry BurgerCharles N. CooleyStan FansherFloyd Ricker

Mailing AddressWeber HallKansas State UniversityManhattan, KS 66506785-532-1241785-532-3474 fax

What is the Livestock and Meat Industry Foundation, Inc.?

The Livestock and Meat Industry Foundation, Inc. (LMIF) has a unique approach for promoting thegrowth and development of the livestock and meat industry. The Livestock and Meat IndustryFoundation, Inc. is a 501(c)(3) non-profit charitable foundation that has nearly thirty years ofexperience supporting animal agriculture.

Accomplishments of the Livestock and Meat Industry Foundation, Inc, to date?

1.

2.3.4.5.6.

Annually provides over $100,000 for scholarships and student enrichment opportunities tostudents in Animal Science and Industry at Kansas State University.Funds Dairy, Poultry, Livestock, Meats, Wool, Horse and Dairy Products Judging Teams.Provided over $500,000 for equipment and supplies for the Weber Hall renovation project.Solicited industry funds for initial research on frozen meat and related marketing studies.Provided funds for the segregated early weaning (SEW) facilities at KSU.Arranged a gift from the Rannells sisters of 2,056 acres of rangeland and purchased 620adjoining acres to be used for range and beef cattle research. The 2,676-acre tract locatedalong Highway 177 south of Manhattan is known as the Hilas Bay Rannells Flint HillsPrairie Preserve.

How can I become a member?

All contributors become members of the LMIF. Gifts of cash, property, livestock, grain, machinery,life insurance, IRA’s, trusts and other methods of giving can be explored. Trusts are a greatinvestment for the donor and the LMIF. A trust pays the donor for their lifetime with the remaindergoing to LMIF at death. Proceeds are used as the donor designated. If you are interested, please writeand we will be glad to explain how a trust works, and show you how charitable giving can have apositive impact in estate planning.

Who controls and distributes these funds?

The board of directors of the Livestock and Meat Industry Foundation is responsible for allocatingLMIF funds according to donor directions. All funds are managed by the KSU Foundation forinvestment purposes and donors receive credit for their contribution from the LMIF and KSUFoundation.

For more information on how you can be a part of this charitable foundation contact:

Dee W. James, Executive Vice PresidentThe Livestock and Meat Industry Foundation, Inc.

134 Weber Hall - KSUManhattan, KS 66506-0201

(785) 532-1226

71


Kansas State University Agricultural Experiment Station and Cooperative Extension Service, Manhattan 66506SRP 861 November 2000It is the policy of Kansas State University Agricultural Experiment Station and Cooperative Extension Service that all persons shall have equal opportunity and access to its educationalprograms, services activities, and materials without regard to race, color, religion, national origin, sex, age, disability. Kansas State University is an Affirmative Action employer. These materialsmay be available in alternative formats. 900


srp861 dairy day 2000lines and test conditions to define acceptable limits for the pi test....

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