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Dairy Cattle Production 342-450A Calf management Page 1 of 24 Department of Animal Science CALF FEEDING & MANAGEMENT Dairy Cattle Production 342-450

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Page 1: Calf feeding & management

Dairy Cattle Production 342-450ACalf management

Page 1 of 24

Department of Animal Science

CALF FEEDING & MANAGEMENT

Dairy Cattle Production 342-450

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Goals for a successful calf management system

1- Building the immune system of the calf as soon as possible after birth.2- Reduce stress and microbial challenges to the calf.3- Provide adequate nutrition4- Provide proper treatments for sick calves.

Immediate care of the calf after birth1- Clean away mucous from the nose and the mouth.

2- Make sure that breathing is initiated, especially after difficult birth. This can be done bytickling the nose or by pouring cold water on the calf's head, which causes the grasping reflex inthe calf

3- Examine the calf for injuries and birth defects.

4- Dry the calf if the cow is not allowed to do so (e.g. in case of Johne's disease).

5- Feed ample amounts of colostrum as soon as possible within the first hour after birth. Use anipple bottle if necessary. Provide a second feeding within 12 hours of birth.

6- Separate the calf from the cow within the first 12 hours of birth after the cow has dried the calfand the calf has nursed. Separate the calf immediately after birth if there is any concern ofinfectious diseases such as Johne's disease.

7- Dip or coat the navel with 7% tincture of iodine.

8- Make sure the calf in properly identified.

Feeding Colostrum

• Colostrum is the first secretion produced by the mammary gland of cows after calving. It isa rich source of protein, fat, minerals and antibodies. The total protein and fat in colostrumare higher while the lactose is lower than in milk (Table 1). Colostrum contains nearly twiceas much total solids as milk. This is attributed mainly to its higher protein content (aboutfourfold) than milk.

• Most of the increase content in protein content is accounted for by the more than 56-foldincrease in immunoglobulin (Ig) content (Table 2). Colostrum of the first milking containsabout 6% Ig. The Ig content then decreases by about 30 and 70% in the second and thirdmilking, respectively. The cow's milk contains less than 0.1% Ig. The Igs are not producedin the mammary gland but passes from the mother’s blood into the milk prior to parturition.The IgG are transferred from blood into the mammary gland and accumulate during lategestation. Transfer of Igs into colostrum is largely completed before calving, therefore

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premilking cows or extensive leakage of colostrum from the udder results in loss of Ig andlower Ig concentration after calving.

Table 1. Composition of colostrum, transitional milk and milk.Time after calving Casein

%Globulin

%Fat%

Lactose%

Ash%

Total solids%

At once 5.00 11.07 6.55 2.90 1.22 26.746 hours 3.50 6.60 7.82 3.29 0.97 22.1812 hours 3.12 2.86 4.10 3.88 0.88 14.8418 hours 3.00 2.14 4.00 3.75 0.85 13.7424 hours 2.61 1.91 3.64 3.82 0.85 12.8336 hours 2.86 1.32 3.58 3.68 0.84 12.1072 hours 2.77 1.10 3.52 4.41 0.84 12.645 days 2.74 1.00 3.55 4.79 0.83 12.9110 days 2.62 0.68 3.57 4.92 0.82 12.61

Table 2. Types of colostral immunoglubulinsIg class Proportion of total (%) FunctionIgG 85-90 Systemic immunityIgM 7 Early immunity and prevention

of septicemiaIgA 5 Not clear

• Colostrum is also a rich source of most mineral and vitamins. Several growth factors (e.g.insulin-like growth factors I & II, epidermal growth factor, and nerve growth factor) as well ashormones (e.g. insulin, cortisol and thyroxin). These growth factors and hormones maystimulate the development of the gastrointestinal tract and other systems in the newborn calf.

Passive Immunity Transfer

• Newborn calves have no disease protection, as blood antibodies can not cross the placentalbarrier from the cow to the calf. Thus the newborn calf is completely dependent on theimmunoglobulin (Ig) passed from its mother via colostrum. The acquisition of Ig through gutabsorption is known as passive transfer.

• A unique characteristic of the small intestine of the newborn calf is the ability to absorb largeprotein molecules such as Ig. However, this capacity only lasts for the first 24 to 36 h of life.The loss of this capacity is known as closure of the gut. Thus it very important that theabsorption of sufficient amount of Ig to provide the calf with passive immunity occurs by thetime gut closure in completed.

• The digestive tract of the new-born calf has several characteristics to minimize digestion of theIg protein and thus to ensure the absorption of intact Ig:

1- Lack of retention of Ig in the stomach.

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2- Bovine colostrum contains trypsin inhibitor that has greater inhibitory effects on trypsin butnot chymotrypsin. This helps protecting Ig and other antimicrobial proteins without affecting thedigestion of other protein in the colostrums, which are important sources of amino acids for thecalf.

• Most of the Igs in colostrum are of the IgG class, particularly IgG1 (80-90% of the total IgG).Optimal protection occurs when all classes of Ig are present together in the colostrum. Studieshave shown that classes of Ig administered individually were not effective in preventing diseasesin newborn calves.

Feeding colostrum

• Calves should receive colostrum in an amount equivalent to 8-10% of their weight with 12 hafter birth. A minimum of 2 liters should be removed and fed to the calf with 30 minutes ofbirth to ensure desired intake has occurred. The second meal should be fed with 6-9 hours afterbirth. On average, the calf should receive 3-4 meals of colostrum with the first 24 hours of life.Recent data showed that the quality (measured as the concentration of IgG in the colostrum) andnot the quantity of colostrums that should be main factor to be considered when feedingcolostrum.

• The amount of colostrum a calf needs to provide adequate immunity depends on:

- Calf body weight.- Concentration of antibodies in the colostrum- Time elapsed between birth and first feeding- Level of infectious agents in the environment

Effects of IgG levels on survival rate of newborn calves

• In most cases colostrum is milked from the cow and the calf is fed through nipple bottle or abucket. Colostrum should be warmed to body temperature (39 °C) in a water bath beforefeeding. If the calf is unable or unwilling to suckle, an esophageal feeder should be used. Asurvey in the US showed that 64% of producers use bucket or bottle to feed colostrum whileabout 33% rely on nursing.

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Excess colostrum can be refrigerated (up to one week)or can be frozen (up to a year) without loosing Igcontent or activity. Frozen colostrum should bethawed in warm water to avoid denaturing the Igprotein. Excess colostrum and transit milk (secretionproduced during the 3rd to the 6th milkings after parturition) can be fed to calves after the firstday.

Determination of Colostrum Quality

• Colostrum quality can be determined using on-farm devisecalled colostrometer. The device is a hydrometer calibratedto take advantage of the linear relationship betweencolostrum specific gravity and Ig concentration.

• The colostrometer classifies colostrum as poor (red) with lessthan 22 mg Ig/mL, moderate (yellow) with 22-50 mg Ig/mLand excellent (green) with greater than 50 mg Ig/mL.Because colostrometer reading is highly dependent ontemperature, colostrum should be tested under standardconditions (room temperature 20-25 °C).

• The main disadvantage of colostrometer is its low cut-off point. In order for the standardfeeding (2 liters) to provide 100 g of IgG, the cutoff of the colostrometer should be increasedto from 50mg/mL to 110 mg/mL.

Testing for Immunity Transfer

• The best indication of a successful transfer of passive immunity is plasma or serum Igconcentration. A passive immunity transfer in considered successful when the plasma Igconcentration is ≥≥ 10 g per liter. Failure of passive transfer in indicated by a bloodconcentration of Ig of less than 10 g per liter at 48 hours of age. However, a concentrationof 15 g per liter is more desirable.

To ensure a successful passive transfer, a 100 g of IgG must be consumed immediately afterbirth. This amount is based on the following assumptions:

1- Plasma volume of the calf is 6.5% of body weight.2- A newborn calf weighs and average of 40 kg.3- Average absorption efficiency of Ig is 25%.

The amount of colostrum needed to supply a 100 grams of Ig will depend on the quality of thecolostrum:- From a good quality colostrum (60 g/L of Ig) the amount will be 100/60 = 1.7 L.- From a low quality colostrum (35g/L of Ig) the amount will be 100/35 = 3 L.

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Milk Replacers

• Development of milk replacers began in the early 1950s in order to make use of surplus milkpowder and products and to conserve fluid milk for retail use. At 4-6 days of age. Milkreplacers usually contain less fat and thus less energy than whole milk.

• Common ingredients in commercial milk replacers include milk byproducts, particularlywhey. Other milk byproducts used include whey protein concentrate, delactosed whey, driedskim milk and casein. Alternative protein include soy, wheat and potato protein concentrates.Skim milk and butter milk are not usually included in the milk replacers due to their cost. Theprimary protein source in most milk replacers is whey, which well digested and utilized bycalves.

• The quality of milk replacers is quite variable from one product to another. The lower-costmilk replacers contain alternative proteins (usually of plant origin) that might have negativeeffects on the health and performance of young calves (< 3 weeks of age). The following pointshould be considered when buying a milk replacer:

- The reputation of the manufacturer.- The chemical composition of the product.- Ingredients included in the products.

• Milk replacers usually contain more than 50% dehydrated skim milk (dry matter basis). Milkreplacers should also contain at least 20% protein (22 to 24% if the replacer contains plantproteins). This is in attempt to compensate for the reduced digestibility and utilization ofamino acids from plant proteins.

• Fat contain of milk replacers should be a minimum of 10%. However, higher fat content (15-20%) is needed when replacers are fed to vealers and calves housed in hutches or in coldenvironment. Chemical composition of a typical replacer is shown in Table 1.

Table 1. Recommended nutrient content in milk replacerNutrient ConcentrationCrude protein (%) 22.0Fat (%) 10.0MacromineralsCalcium (%) 0.70Phosphorous (%) 0.60Magnesium (%) 0.07Potassium (%) 0.60Sodium (%) 0.10Chloride (%) 0.20Sulfur (%) 0.29MicromineralsIron (mg/kg) 100.0Cobalt (mg/kg) 0.10Copper (mg/kg) 10.0Manganese (mg/kg) 40.0

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Zinc (mg/kg) 40.0Iodine (mg/kg) 0.25Selenium (mg/kg) 0.30VitaminsVitamin A (IU/kg) 3800Vitamin D (IU/kg) 600Vitamin E (IU/kg) 40.0

• To encourage, early consumption of milk calf starter, calves can be limit-fed all-milkreplacers containing 18% protein. However, milk replacers should contain more than 18%protein (20 to 24%) when calves are fed ad libitum amounts of milk replacer for maximumdaily gain.

Classification of Milk Replacers

• Milk replacers can be divided into two groups based on protein source:

1- All milk: contains only milk ingredients

2- Alternative: contains some proteins of non-milk sources. Milk replacers containing less than50% total milk solids are known as Milk substitutes.

• A common practice in formulating alternative milk replacers is to replace 50% of the milkprotein with lower cost plant proteins

Acceptable protein sources include:- Soy protein concentrate- Soy protein isolates- Modified wheat protein

Unacceptable protein sources include:- Pea flour.- Lupin flour.- Wheat flour.- Fishmeal- Whole blood protein

• During the first three weeks of age, heifer calves being raised as replacement heifers should befed only all-milk replacers. This is because the digestive system of newborn calves isincapable of digesting alternative protein sources. After three weeks of age, calves can beswitched to alternative milk replacers. The alternative milk replacers are also suitable for vealcalves and calves destined for beef production.

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Mixing and Feeding Considerations

• For replacement calves, the recommendation is to feed about 450 grams of milk replacerpowder per day. The mixing recommendations indicated in the product label should befollowed carefully, especially the temperate of water used for reconstitution.

• Milk replacers should be mixed until all powder is in suspension and all clumps are dissolved.The reconstituted milk replacer should contain between 10 and 15% dry matter. In coldweather, the dry matter content can be increased to 25% to enhance nutrient intake. Most ofmilk replacers are mixed in the ratio of one part of milk replacer to seven parts of water

Management of liquid feeding of calves

Setting the level of liquid feeding is critical because:

1- Sufficient amount of nutrients must be given to ensure optimum health and growth.

2- Feeding excessive amounts of liquid feed, particularly milk replacers can cause digestive

upsets and diarrhea.

3- The difference between the need and an excess is small in young calves.

The amount of liquid feed that should be fed is mainly determined by:

1- Body weight of the calf.

2- Season of year (winter vs summer)

3- Feeding frequency (number of feedings per day).

• Liquid feeds (milk or milk replacers) should be fed at the rate of 8 to 10% of body weight.Calves are traditionally fed twice. Feeding once daily gives similar results in most cases.However, twice daily feeding in recommended for the following:

1- Sick calves

2- When high level of feed intake is required (e.g. veal calves).

3- When feeding a milk replacer that is less than high quality.

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Characteristics of feeds for calf before weaningColostrum Milk Milk replacer

powderMilk replacer

with waterSkim milk

Protein (%) 14 32 20 2.5 3.2Fat (%) 7 3.7 10 1.3 0.1Lactose (%) 3 5.0 variable - 5.0Ash (%) 1.2 0.7 variable - 1.2Total solids (%) 25.2 12.6 90 11.3 9.5TDN (% as fed) 32.8 16.4 95 11.9 8.6TDN (% DM) 130 130 106 106.0 91

TDN required by a 45 kg Holstein calf gaining 300 g/day = 0.74 kg TDN/day (NRC 1989)

Amount of feed required to meet TDN requirement:Colostrum 2.5 kg/day (some calves may consume up to 6 liters/dayMilk 4.5 kg/dayMilk replacer powder 0.78 kg/dayMilk replacer solution 6.2 kg/day (7 liters/kg of powder)Skim milk 8.6 kg/day

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Digestion and Metabolism in Newborn Calf (Preruminant)

The newborn calf is not a ruminantPreruminant refers to the period after birth when the calf is dependent on milk (or milk replacers)as it’s major food. At birth and during the first few weeks of life, the compartments of thedigestive system (i.e. rumen, reticulum, and omasum)are undeveloped. In contrast to the mature cow, theabomasum (true stomach) of the newborn calf is themain compartment, constituting 60% of the total tissueweight of the stomach. At this stage of life, the rumenis nonfunctional and the calf cannot utilize some feedsdigested by the adult.

During nursing or feeding from a bucket, milkbypasses the rumen via the esophageal groove andpasses directly to the abomasum. Reflex action closes the groove to form a tube-like structure,which prevents milk or milk replacer from entering the rumen. When milk is consumed veryrapidly, some may overflow into the rumen.

Esophageal Groove

A unique feature of the preruminant digestive system. It is afold of tissue that leads from the base of the esophagus tothe reticulo-rumen orifice. Contractions of muscles in thisfold of tissue forms a tube called the esophageal groove,through which milk and other liquids bypasses the reticulo-rumen to the abomasum. The closure of the esophagealgroove is a conditioned reflex initiated mainly by visual andother stimuli that the young associated with feeding.

Protein Digestion

• Inactive pepsin and chymosin are secreted by abomasal mucosa. The enzymes are activatedby the acidic (HCl) condition of the abomasum. Chymosin is the major enzyme responsiblefor clot or curd formation. Breaking peptide bonds of κ-casein polypeptide chain in thepresence of Ca ions, results in the coagulation of the casein in milk. Chymosin activity isrelatively high at 2 days of age but declines with age (2-4 weeks in lambs). Chymosinactivities decline sharply at weaning. Pepsin activity increases upon introduction of solid foodand is proportional to increased body weight. After weaning, pepsin is the main abomasalenzyme.

• Abomasal digesta entering the duodenum after a meal of whole milk contains little intactcasein, indicating that this protein is extensively hydrolyzed in the abomasum. The whey

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protein α-lacalbumin is also hydrolzed in the abomasum whereas β-lactoglobulin is relativelyunaltered by abomasum enzymes.

• In the small intestine, protein is digested first by the action of pancreatic proteases (trypsinand chymotrypsin) and then by the action of peptidases secreted by pancreas and intestinalmucosa. Milk proteins are highly digestible (> 95%). Plant proteins used in milk replacers areless digestible than milk proteins. Regardless of protein type, protein digestibility improveswith age, which correlates with maturation of the proteolytic activities of the digestive system.

Fat Digestion and Absorption

• The first enzyme added to the ingesta is pregastric esterase (secreted by salivary glands). Theenzyme hydrolyzes short-chain fatty acids and has a limited effect on long-chain fatty acids.The abomasum does not have any lipolytic enzymes. However, hydrolysis of milk lipidscontinues in the abomasum by the action of pregastric esterase.

• Most of milk fat digestion occurs in the small intestine by the action of pancreatic lipase. Mostof milk long-chain fatty acids are hydrolyzed by the action of pancreatic lipase. The endproducts of milk lipid digestion are free fatty acids, mono- and di-acylglycerols.

• Milk fat is almost 100% digestible by calves. The digestibility of animal and plant lipids usedin milk replacers is also high providing they are emulsified to particle sizes less than 3-4 µmby homogenization.

Digestion and Absorption of Carbohydrates

• Except for lactase, other carbohydrate digesting enzymes are found in low concentrations inthe digestive system of the newborn calf. Consequently, utilization of any disaccharides orpolysaccharides other than lactose is very limited in young calves.

• The calf lacks sucrase and amylase that are present in the young of many nonruminants.Intestinal maltase and pancreatic amylase are found in limited amounts at birth but increase inactivity with age. Post-ruminal digestion of starch and maltose increases considerably duringthe first three months but remains lower compared with monogastric animals.

Colostral Immunoglobulin Absorption

The intestine of the neonatal calf is permeable to colostral immunoglobulins for a short period oftime after birth and therefore a delay in the consumption of colostrum greatly reduces γ-globulinuptake. The ileum is the primary site of γ-globulin absorption. Reduction in absorption ofimmunoglobulin bodies is related to renewal of intestinal lining that occurs 40-48 hours afterbirth.

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Development of the Rumen

• As long as the calf remains on milk, the rumen remains undeveloped. When calves beginconsuming solid food, a microbial population becomes established in the rumen andreticulum. End products of microbial fermentation (i.e. volatile fatty acids) are responsible forthe development of the rumen. This occurs as early as 3 weeks of age with most feedingprograms. If grain feeding with or without forage is started during the first few weeks of life,the rumen will become larger and heavier with papillae

development, and will begin functioning like the adult's when the calf is about 3 months of age.

Butyric and propionic (mostly butyric) acids are the major stimulants of tissue growth of therumen because:

1- They are metabolized by ruminal tissue during absorption. Their metabolism provides theenergy for growth of the epithelial cells.

2- They have direct effects of proliferation and differentiation of gastro-intestinal epithelial cells.

Feeding grains produces more propionic and butyric acids than does feeding forages. Therefore,development of the forestomach tissue and a papillae are more responsive to grain than forageintake. It is recommended that forage feeding should be withheld until after weaning.

Ruminalpapillae of acalf fed all-grain starters

Ruminalpapillae of acalf fed gain+ hay starter

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• At about 12 to 16 weeks of age, the proportions of the four compartments of the fore-stomachwill be similar to those of a mature animal (see figures). Based on tissue weight theproportions are 76, 18, and 15% for the reticulorumen, omasum and abomasum, respectively.At birth the proportions are 38, 13, and 49%, respectively.

Development of Ruminal Microbial Population

• Ruminal microbial population is greatly influenced by diet and ruminal pH. During the firstthree weeks of life, the predominant ruminal microbes are aerobic or facultative bacteria. Asdry matter intake increases, lactic acid may become the major product of fermentation. Thisis particularly true in early-weaned calves, which receive highly fermentable carbohydrates inpre-starters. This results in a very low ruminal pH. During this period, the anaerobic bacterialpopulation increases in this period resulting in a more diverse microbial population.

• At about six weeks of age, microbial population similar to that of adults predominates withsome characteristics of calf microbial population still remains. By 9-13 weeks bacterialpopulation that utilizes cellulose and hemicellulose as energy sources become dominant andruminal pH and substrate availability are more favorable for the growth of these micro-organisms.

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Calf Weaning

A calf should not be weaned until it rumen is functional and capable of supporting the calf’snutritional needs. Calves are usually weaned by weight and appetite rather than age. As a rule ofthumb, calves can be weaned abruptly when they consume 800 to 1000 g of starter for twoconsecutive days (not less than 500 g). This usually happens when calves are 35 to 40 days oldand weigh 65 to 70 kg (Holstein calves).

Under a good calf management program, Holstein calves can be weaned at 3 to 5 weeks of age(early weaning). However, weaning in most commercial herds is at 6 to 8 weeks of age. Jerseyand Guernsey calves are usually weaned at older ages than Holstein calves. To ensure early andsuccessful weaning, water and good quality starter must be available by the time the calf is 7 to10 days old.

Importance of offering forages before weaning

Forages are important in stimulating rumination, which will begin to take place at about twomonths of age. However, high forage intake may slow down the development of ruminal papillaedue to lower production of propionate and butyrate relative to acetate.

Importance of calf starter

• Rumen development takes place rapidly between 4 and 8 weeks of age. Starters are moreimportant than forages as a source of fermentable carbohydrate for rumen development.Production of volatile fatty acids, particularly propionic and butyric acid in the rumenstimulates development of the rumen and thereticulorumen. Grain starter should be offeredas early as four days after birth and shouldcontinue until about four months of age.

• Calves should be encouraged to consume starterby placing a small amount in the bottom of thebucket from which the liquid diet is fed or handfeeding small amounts. Starter intake usuallybecomes measurable between 7 and 14 days ofage.

Quality of calf starterCalf starter should be:1- High quality.2- Fresh.3- Palatable.4- Coarse textured.

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Nutrient specifications of calf startersCrude protein 18-20%Total digestible nutrients 80%Acid detergent fiber 15%Ether extract 3-5%Calcium 0.6%Phosphorous 0.4%Copper 10 mg/kgZinc 42 mg/kgManganese 30 mg/kgVitamin A 6000 IU/kgVitamin D 1400 IU/kgVitamin E 50 IU/kg

Examples of calf starters

Several types of calf starters are available (Table 3a,b):1- Prestarter: contains milk powder as well as cereal grains, oilseed meals, byproduct feeds

and mineral-vitamin mix.2- Regular (grain) starter: 16 to 20% crude protein and contains cereal grains, oilseed meals,

byproduct feeds and mineral-vitamin mix.3- High fiber starter (complete ration): complete calf rations contain up to 50% forage or

fibrous byproducts such as cottonseed hulls, oat hulls or sun-cured alfalfa

Table 3a. Example of calf-starter diet (mash form)Ration

A B CCracked or coarsely ground corn and cob meal 50Cracked or coarsely ground shelled corn 51 37Cracked or coarsely ground barley, oats or wheat 25 25.5 37Soybean meal 17.5 16Sunflower meal 18.5Molasses 5 5 5Mineral and vitamin premix 1.5 1.5 1.5Trace mineral salt 1 1 1

Table 3,b. Example of calf-starter diet (pelleted starter)Ingredient %Wheat 30Barley 21Oats 16.5Soybean meal 14Canola meal 4Dehydrated alfalfa meal 4Spray dried whole milk 3

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Molasses 5Mineral-vitamin premix 2Ground limestone 0.3Cobalt-iodized salt 0.2

Calves should be allowed to 1.5 to 2 kg of starter daily plus all the good forage they could eat.Water should be available all the time. Salt and mineral supplements up to 90 g per day may beprovided. Calves will depend on starters as their main source of nutrients up to 4 months of age.

Expected body weight gain before weaningLiquid diets supplemented with a starter should allow calves to gain 250-400 g/day. It isimportant to remember that the objective of the pre-weaning feeding is not to maximize bodyweight gain but rather to insure good health and good skeletal growth.

Figure 1. Consumption of grain starter and body weight gain of calves fed milk at a constant rate and free choiceforage.

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Other Managerial Aspects for the Dairy Calf

Housing

• The calf housing facilities should be comfortable for the calf and convenient for the stockperson.General requirements include individual housing for each calf, dry, well ventilated pens withample of bedding, and isolation from older animals.

• A popular housing system for dairy calves is theportable outside hutches. The hutches should be placedin a well-drained and protected area with south-facingopen front. Only one calf should be place in individualhutch (1.5 x 2.5 m). Lots of bedding should be used tokeep the calf dry and to prevent the straw from freezingin winter. Hutches should be cleaned and disinfectedbetween calves.

• Weaned calves can be moved to calf grow-out facilitiessuch as outside pens with overhead shelter. The movecan be made when the calves are as young as 4 monthsof age or as old as 6 months of age. The calves can beplaced in groups of up to 12 calves each. The age andsize spread should not be more than 2 months and 50 kg, respectively. Allow about 3 m2 per calfand 25 cm of feed space

Identification

Identification of calves is an important managerial tool that guarantees accuracy of heat dates,breeding dates, calving dates and monthly milk weights. Every calf should be identified at birthwith a permanent visible herd number. Permanent identification is also required to registerpurebred calves. Identification numbers should not be duplicated. Branding is anotheridentification method. Calves are usually branded before its one-month old by either freeze-drying or hot branding.

Extra teatsExtra teats on cow's udder can be a site for infection and may interfere with machine milking.Extra teats should be removed as a soon as they can be identified. Calves should be checked atbirth and extra teats should be removed at the line where the teat joins the udder using sharpscissors or a serrated curved shears. A veterinarian should be consulted if there is any doubt as towhich teats are supernumerary.

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Dehorning

Calves are usually horned as soon as the horn buttons can be felt, usually between one and twoweeks of age. Dehorning can be done with caustic potash or electric dehorner. A veterinarianshould be consulted regarding which dehorning method to use.

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Veal Production

Two types of veal are produced:1- Red veal2- White veal

Red Veal

In this system, calves are raised as on milk or milk replacers up to 6-8 weeks of age and thenintroduced to all concentrate feeding system. The concentrate rations may be made of whole cornor barley and supplement pellets to give a concentrate diet with 16-18% protein. Rate of gain is1.4-1.8 kg/day with a feed conversion of 3:1 or less.

White VealWhite veal refers to the anemia resulting from feeding milk or milk replacers, which contain lowlevels of iron. Vealer milk replacers are similar to regular milk replacers but contain a higherlevel of fat.

The calves are gradually brought to an intake of 9-12 kg of milk daily and maintained at thatlevel until they reached the market weight (140-150 kg). The feed conversion is about 10 kg ofmilk per kg of gain. White veal is often raised with reduced lightning in order to minimizeactivity and maximize feed conversion.

Profitability of veal production depends on:- Market price of veal- Alternative value of milk and cost of milk replacers.- Initial size and cost of the calf.

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Scours (Diarrhea)

Scours or neonatal diarrhea is the primary cause of death in unweaned calves (50 to 60%).

Primary Cause- Infectious agents; bacteria, viruses, and protozoa (microbial diarrhea)- Improper nutrition (Nutritional diarrhea).

Predisposing factors:- Inadequate intake of colostrum- Using milk with high bacterial count- Feeding milk or milk products at irregular time or irregular amounts.- Feeding poor quality milk replacers, especially calves less than 3 weeks of age.- Poor sanitation of feeding equipment.- Keeping calves in dirty pens or exposed to scouring calves.

Types of Neonatal Diarrhea

Diarrhea in newborn calves can be classified into two groups:1- Nutritional diarrhea: Results from ingesting too much milk or a milk that is not

properly digested (i.e. bad quality milk replacer). Overfeeding milk to hungry calves Themain cause of nutritional diarrhea is lactic acid bacteria. Excessive fermentation of sugars(e.g. lactose) in the large intestine results in the production of large quantities of lacticacid. Osmotic pressure increases and pH is lowered in the intestine. As a result, waterwill be drawn from the body into the intestine causing diarrhea

2- Infectious diarrhea: Caused by infectious agents mainly E. coli. Infectious diarrhea isthe most common health problem in young calves when predisposing factors are notwell-controlled. The incidence of fatal E. coli infections is high during the first twoweeks of life. Affected calves that survive this period, usually recover.

Two types of E. coli infections can be identified:a- Septicemia: E. coli may cross the intestinal wall and enter the blood stream

causing septicemia. The highest mortality occurs during the second and third dayafter birth.

b- Enterotoxemia: E. coli produces toxins that cause localized intestinalinflammation. Peak mortality occurs at about 6-7 days of age.

Signs

A major loss of water in the feces. This accompanied by massive loss of electrolytes (Na, Cl andK, Table 4). A healthy calf losses 5% of water intake in feces whereas a diarrheic calf could loseup to 80% of water intake, or 50% extracellular fluid volume.

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Occurrence of diarrhea in young calve is sudden and acute and the calf can loose up to 12% of itsbody fluid within 24 hours.

Table 4. Electrolytes balances (g per day) in normal and diarrheic calves.Electrolytes Normal calf Diarrheic calvesSodium +0.38 -10.70Potassium +1.31 -3.00Chloride -0.93 -12.70Calcium +5.52 +1.00Magnesium +0.34 -0.26

Degrees and signs of dehydration- < 6% no clinical signs- 6-8% sunken eyes, dry mouth and nose- 8-10% Loss of body weight, more distinct sunken eyes, reduction in urine output.- 10-14% Cold extremities, calf remains down, poor peripheral pulses.- > 12-14 shock and death

Most calves that die from diarrhea do not die as a result of the infectious agent but rather fromdehydration and imbalance of electrolytes.

Treatments

• The key to successful treatment of calf diarrhea is early detection and early administration of awell-balanced oral rehydration products (electrolytes). Oral electrolyte treatment should start atthe first sign of diarrhea (excretion of large volume of loose watery feces). In severe cases ofdehydration (10% or more), intravenous feeding may be necessary.

• Scouring calves treated with an electrolyte solution should continue to receive their normalfeeding of milk or milk replacer. This is because the electrolyte solutions do not contain enoughnutrients to meet the energy requirements of the calf. Electrolytes solution can be classifiedbased on the pH of the solution into alkaline and acidic electrolytes. Acidic electrolyte solutionmay be fed immediately after a meal of milk as they may help protein co-aggulation anddigestion. However, alkaline electrolyte solutions are more effective when they are fed 3-4 hoursafter a meal, as they may interfere with milk-co-aggulation.

Other DiseasesPneumonia (inflammation of the lungs): Respiratory diseases occur between 4-6 weeks of age.Calves with chronic pneumonia seldom recover and should not be used for replacement.Pneumonia may vary from subclinical to acute and fatal. Rate of morbidity (incidence of disease)is high but mortality rate is quite variable. Pneumonia can be caused by bacteria (e.g. Pasteurellamultocida), virus (e.g. Parainfluenza Type 3) and mycoplasma (e.g. Mycoplasma dispar).

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Pneumonia usually follows other infectious diseases. The organisms associated with the diseaseoften cannot cause clinical signs without the presence of predisposing factors.

Clinical signs of pneumoniaClinical signs are variable and are generally observed in various combinations:1- Nasal discharges2- Dry cough, especially noticeable after exercise.3- Rectal temperature > 41 °C (normal temperature 39 °C).4- Difficult breathing5- Lesions of the lungs.

Predisposing factors:

1- Reduced immunity and / or continuous challenge from microbes (contaminatedenvironment).

2- Poor ventilation and high relative humidity.3- Poor feeding management (overfeeding of colostrum or milk replacers)4- Poor housing management (too early weaning, too early grouping, stress due to

transportation)

Treatment of pneumonia: Calves with pneumonia should be placed in a dry well-ventilated environment. Antibiotics are usually given to reduce the effects of secondarybacterial infections.

Prevention of pneumonia: Reduction or elimination of predisposing factors willsignificantly reduce the occurrence of pneumonia. Adequate intake of colostrum,avoidance of nutritional stress, proper housing and good natural ventilation are effectiveways of reducing the incidence on pneumonia. Vaccination program relevant to agentsprevalent in an area may be planned under veterinarian supervision.

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Birth, colostrum (2-3 days)

Whole milk, milk replacer, milk substitute, sour colostrum, (starter, hay)

6-8 weeks, weaning starter (0.5-1.0 kg daily) hay, water

16 weeks, forage (hay, silage, pasture) grower (0.05-2.0 kg/day)

15 months, breeding forage, concentrate (0.5-2.0 kg/day)

24-24 months, calving

Dairy Calf FeedingTypes of feed and subsequent use

Individual pens, hutches300-400 g/day gain

Grouppens600-700 g/day gain

Groups700 g/day gain

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Nutritional considerations for the newborn calf.Age

(week)Formof diet

Energy source Nitrogen sources

Fats Simplesugars

Starch Cellulose &hemicllulose

Animalprotein

Plantprotein

NPN

Preruminant 0-4 Liquid Emulsified Lactoseonly

No No Milk No No

Transitional 4-8 Liquid Emulsified Lactoseonly

No No Yes Max.50%

No

>8 Dryfeed

supplemental No yes Yes No yes No

Further readings:

Technical Dairy Guide (CD): Raising dairy heifers. The Babcock Institute for InternationalDairy Research and Development. Madison, WI.Davis, C. L. and Drackley, J. K. 1998. The Development, Nutrition, and Management of theYoung Calf. Iowa State University Press, Ames, Iowa. (In the library).

http://www.das.psu.edu/dcn/calfmgt/. A comprehensive site for dairy calf & heifermanagement

http://www.das.psu.edu/dcn/calfmgt/slides2/index.html. A slide show about dairy calf feeding& management.

http://www.das.psu.edu/dcn/calfmgt/rumen/index.html. Images of calf rumens.