copyright 2016, tosha l. opheim

Beef production sustainability: The water use efficiency of distillers grain in Texas High Plains

beef production and the use of byproducts in Honduran beef finishing systems

Tosha Lynae Opheim, B.S.

A Thesis

Animal Science

Submitted to the Graduate Faculty

of Texas Tech University in

Partial Fulfillment of

The Requirement for

The Degree of

MASTER OF SCIENCE

Mindy M. Brashears, Ph.D.

Chair of Committee

Sara J. Trojan, Ph.D.

Markus F. Miller, Ph.D.

Jhones O. Sarturi, Ph.D.

Charles P. West, Ph.D.

Mark A. Sheridan

Dean of the Graduate School

August 2016

Texas Tech University, Tosha L. Opheim, August 2016

ACKNOWLEDGEMENTS

First, I would like to thank Dr. Trojan for giving me the chance to attend Texas

Tech University to continue my education. The opportunities I have been given while

attending Texas Tech are truly innumerable. Dr. Trojan has pushed me, challenged me,

and supported me and by doing so has helped me to grow as both a student and a person.

A special thank you goes to Dr. Mindy Brashears as she saw something in me that I did

not even see in myself. She has inspired me to go outside the “comfort zone”, challenge

the “norms”, and to see the “big picture”. Undoubtedly, her guidance has pushed me to

see beyond the science. Another special thank you goes to Dr. Miller as he has afforded

me the opportunity to be a part of the team and encouraged me every step of the way. It

has been not only a privilege, but an honor to travel and work closely with both Dr.

Brashears and Dr. Miller. I would also like to thank Dr. Sarturi and Dr. West. They have

gone the extra mile for me, taking a vested interest in my success and for that I am truly

grateful.

Secondly, I would like to thank the graduate students, interns, undergraduates,

and staff that have not only helped me with my projects, but helped to shape me during

my time at Tech. A special shout goes out to Maria Bueso for her support and guidance

while traveling and working together. If it were not for her friendship, this “gringa” may

not have survived Honduras. Thank you to all who have traveled with me and made our

trips so memorable Remy Carmichael, Andrea English, Keelyn Hanlon, Ana Gomez,

Brenda Inestroza, Nick Hardcastle, J Ricardo Gomez, Sarahi Morales, and Amber

Anderson. A special thanks to Pedro Campanilli, Barbara Lemos, and Lauren Ovinge for

their help in the lab and the feedlot. And last but not least, thank you to Zach Smith, Alex

Thompson, Jessica Baggerman, Loni Lucherk, and Valerie Manning for your friendship

and guidance over the last two years.

Thirdly, I would like to take the time to thank my Honduran families for taking

care of me while I traveled throughout Honduras. Thank you to the Gomez family for

everything they have done for me in Honduras; on numerous occasions they welcomed

me into their home, fed me, and taught me so much about their country and culture. Also

thank you to the Bueso and Ponce families for their hospitality and welcoming homes.

Ricardo Paz, Gustavo Valdivia, and all of the producers and people I worked with, thank

you for challenging me and always watching out for me. I truly feel as though I have

family in Honduras because of all of the amazing people I have met.

Lastly, thank you to my family and friends back home for supporting me to

continue my education, move across the country, travel internationally, and to do what I

love. My parents, Tom and Dixie, taught me the value of hard work and that I could do

whatever I set my mind to, and for that I am beyond grateful. My siblings, Cade and

Lexi, have been with me through every step of the way; their friendship and

encouragement has helped me to continue pushing forward. My family’s love and

unwavering belief in me has allowed me to succeed and a simple thank-you does not

even begin to cover it all.

TABLE OF CONTENTS

ACKNOWLEDGEMENTS……………………………………….....................................ii

LIST OF TABLES……………………………………………..........................................vi

LIST OF FIGURES...........................................................................................................vii

I. INTRODUCTION…………………………………………………….........................1

II. REVIEW OF LITERATURE ………………………………..................………….....3

Introduction.......................................................................................................3

History of Distillers Grain.................................................................................3

Distillers Grain Processing................................................................................5

Feeding Distillers Grains...................................................................................7

History of Palm Kernel....................................................................................21

Palm Kernel Processing...................................................................................21

Feeding Palm Kernel Meal to Livestock.........................................................22

Conclusions......................................................................................................23

Literature Cited................................................................................................25

III. THE RELATIONSHIP BETWEEN CROP WATER USE AND FINISHING

PERFORMANCE OF BEEF STEERS FED DIETS CONTAINING CORN OR

SORGHUM DISTILLERS COPRODUCTS…………………………………...........35

Abstract............................................................................................................35

Introduction......................................................................................................37

Materials and Methods.....................................................................................38

Results and Discussion....................................................................................41

Implications.....................................................................................................46

Literature Cited...............................................................................................47

IV. UTILIZATION OF LOCAL BYPRODUCTS IN BEEF FINISHING DIETS IN

HONDURAS: DESCRIPTIVE ASSESSMENT OF GROWTH PERFORMANCE

AND CARCASS CHARACTERISTICS....................................................................54

Abstract............................................................................................................54

Introduction......................................................................................................56

Materials and Methods.....................................................................................57

Results and Discussion....................................................................................63

Implications......................................................................................................67

Literature Cited................................................................................................68

V. CONCLUSION............................................................................................................76

VI. APPENDICES............................................................................................................78

Additional Honduras Trials..............................................................................80

LIST OF TABLES

3.1. Ingredient composition of corn and sorghum coproducts diets fed to beef steers....50

3.2. Conversion factors and calculated values.................................................................51

4.1. Ingredient composition (DM basis) of the experimental diets fed in Honduras

finishing trials...........................................................................................................72

4.2. Descriptive statistics for beef cattle finishing diets in Honduras..............................73

4.3. Descriptive growth performance, carcass, and cost statistics for individual

finishing diets............................................................................................................74

A-1. TAWC Grain Sorghum yield and total crop water 2005-2014.................................77

A-2. TAWC Corn yield and total crop water 2005-2014..................................................78

LIST OF FIGURES

3.1. Yield response to water input...................................................................................52

3.2. Water use efficiency of beef production...................................................................53

4.1. Honduran producer map...........................................................................................71

CHAPTER 1

INTRODUCTION

Protein is an essential nutrient for humans and animals as it vital for repair and

synthesis of tissues, particularly muscle (Miller. E. L., 2002, World Health Organization,

2002). Humans can utilize many different sources of protein; although, the most nutrient-

dense sources of complete proteins are animal-based. Beef, milk, and eggs have the

highest protein to energy ratios and the highest digestibility (Millward and Jackson,

2003). Protein production is vital not only for the economy but also for food security.

From 1981 to 1994 it was estimated that 80% of cereal grains were consumed as

direct food sources in developing countries (Rosegrant et al., 1999). Within developed

countries, the use of byproducts in livestock production has helped to shift a percentage

of the diet away from direct cereal grain use. Ethanol continues to play an important role

in the U.S.; therefore, the abundance of distillers grains allows for continued use in

livestock production. Developing countries tend to rely on industries other than ethanol

for byproduct feeds and economic stimulation. The palm kernel industry is an important

source of economic return for the country of Honduras. Palm kernel meal is a byproduct

of that industry and can be utilized in animal production; however, palm kernel meal is

oftentimes underutilized in Honduras.

Ruminants are able to effectively utilize byproducts from animal and industrial

production to create a high-quality and nutritionally rich protein source. As the

importance of sustainability within agricultural production increases, the use of

byproducts will continue. In developed countries such as the U. S. sustainability in

agricultural production will focus on aspects such as water, crop yield potential, and

efficiency of production and use of byproduct feeds. Tradeoffs between the yield

efficiency of crops, the water use efficiency of crops, and the animals’ ability to

efficiently utilize the grain and/or byproduct feeds in production will be important to

realize for more sustainable production. For developing countries such as Honduras,

understanding the role byproducts have in livestock production and increasing their use

will help to create more sustainable livestock production practices.

CHAPTER II

REVIEW OF LITERATURE

Introduction

Rumen microbial fermentation, allows ruminants to digest forages and other

feedstuffs that nonruminants cannot utilize efficiently which enables readily available

byproducts to be used in ruminant diet formulation. Many industrial byproducts are

fibrous in nature, because other nutrients like starch and oil have been removed for other

primary products such as ethanol, corn syrup, and plastics. Due to the resulting

alterations in chemical composition, many byproducts are well-suited for ruminant use.

Byproduct feedstuffs are derived from a range of processes and have different physical

and chemical properties compared to their corresponding whole grain source. Within the

United States, byproducts from ethanol and biofuel industries play important roles in the

U.S. livestock feeding industry. In many other countries, palm oil byproducts are of equal

importance. The production and feeding history will be reviewed.

History of Distillers Grain

The use of distillers grain (DG) in animal production has a long history with many

changes and technologies adapted over the years. In the 1700’s, many European countries

utilized the wet byproduct of alcohol distillation as a feed source for livestock (Liu and

Rosentrater, 2012). It is believed that this practice was slowly adopted in the United

States during the 1800’s; however, it was not until the late 1800’s that the drying of

byproduct grains began (Liu and Rosentrater, 2012). In the early 1900’s, research on the

use of DG byproducts in dairy rations first emerged. The Association of Feed Control

Officials (AAFCO) developed definitions for DG in 1913, and by 1915 the American

Society of Animal Science Committee adopted them (Committee on Terminology, 1915).

Prohibition within the United States slowed production to a near halt during the 1920’s

and early 30’s, but resumed following the end of prohibition (Liu and Rosentrater, 2012).

After the adoption of distillers’ definitions and the resumption of distilleries, the need for

distillers within animal production was realized and led to improvements in distillation,

drying, and marketing.

It was not until the energy crisis in the1970’s that ethanol distillation emerged.

Ethanol subsidies led to the construction of new ethanol plants; however, many were

poorly designed which resulted in poor feed-quality, inconsistent DG byproducts (Liu

and Rosentrater, 2012). During the 1990’s, many new ethanol plants were built, and the

distillation process was further improved (Liu and Rosentrater, 2012). Subsequent DG

vastly improved in quality, further cementing its place in livestock production.

Due to the large quantities of corn produced, particularly in the Midwest, most of

the initial ethanol production was corn-based (Liu and Rosentrater, 2012). Corn has

continued to be the predominant grain source, however, the increase in grain sorghum

production in water-limited regions in the United States has led to an increased number of

ethanol plants utilizing sorghum. One of the most recent advances in cereal grain ethanol

production is further processing to remove oil, resulting in a low-fat, deoiled corn

distillers byproduct. By removing additional corn oil, ethanol production profitability has

increased. The evolution of the ethanol industry has proven to be dynamic, with rapid

technological advances in processing and additional byproducts (Liu and Rosentrater,

2012). As the importance of ethanol byproducts were realized, DG quickly transitioned

from secondary resultants of the ethanol process to coproducts contributing 10-40% of

ethanol plant’s total revenue (Liu and Rosentrater, 2012). Availability and cost (relative

to corn) have been two factors driving the inclusion of coproducts to beef finishing diets

(Westcott, 2007). Ethanol plants have been heavily concentrated in high corn producing

regions, as a result, greater feeding of coproducts to ruminants occurs in the U.S. corn

Distillers Grain Processing

The two primary processes for ethanol distillation are dry grinding and wet

milling (Rausch and Belyea, 2005). Dry grinding is the most common process used in

ethanol production today as it is a simpler process with lower capital costs. According to

the 2012 Ethanol Industry Outlook, approximately 90% of ethanol production was dry

grinding, and 10% was produced by wet milling (Renewable Fuels Association, 2012).

Dry grinding is a five step process to recover fuel ethanol (Bothast and Schlicher,

2005). These steps include grinding the grain, cooking, liquefaction, saccharifaction, and

fermentation. Initially the grain source is ground and water is added to create a mash.

After cooking the mash, enzymes are added to assist in the conversion of starch to sugar.

Alpha-amylase enzymes are added to the hot mash to reduce the size of starch polymer

and aid in the breakdown of the starch. After the mash has cooled, glucoamylase enzymes

are added which convert the small starch polymers to glucose. Next, yeast is added to

ferment the sugars (glucose) contained within the mash; the mash is then distilled and

fuel ethanol is recovered. Whole stillage, the remaining fractions after the removal of

ethanol, is centrifuged to separate the thin stillage from the grain fraction. The resulting

grain fraction is wet DG, which can be dried (dried DG). The thin stillage is condensed

through evaporation until the subsequent fraction is a thick syrup. This syrup is also

known as condensed solubles which may be added back into the wet DG at varying

inclusion levels. Wet DG with solubles (WDGS) can also be dried at this point (Bothast

and Schlicher, 2005).

According to AAFCO (2016), the definitions of ethanol coproducts are:

Distillers Dried Grains (DDG): obtained after the removal of ethyl alcohol by

distillation from the yeast fermentation of a grain or a grain mixture by separating

the resultant coarse grain fraction of the whole stillage and drying it.

Distillers Dried Grains with Solubles (DDGS): obtained after the removal of

ethyl alcohol by distillation from the yeast fermentation of a grain or a grain

mixture by condensing and drying at least ¾ of the solids of the resultant whole

stillage.

Distillers Wet Grains (DWG): the product obtained after the removal of ethyl

alcohol by distillation from the yeast fermentation of a grain or a grain mixture.

Condensed Distillers Solubles (CDS): obtained after the removal of ethyl

alcohol by distillation from the yeast fermentation of a grain or a grain mixture by

condensing the thin stillage fraction to a semi-solid.

Deoiled corn distilllers dried grains with solubles, solvent extracted: the

product resulting from the solvent extraction of oil from DDGS to result in a

crude fat content of less than 3% on an as fed basis. (Proposed definition, 2015)

Within the last 5 to 10 years, several dry grind ethanol plants have implemented

further processing technologies to remove additional corn oil from the DG coproducts

(Liu and Rosentrater, 2012). Corn oil is increasingly utilized in the synthesis of biofuel

and as a biofiller in plastics, which has increased the demand for corn oil and driven

production ethanol production profits (Liu and Rosentrater, 2012). According to Musser

(2013), from 2011 to 2013, there was a 33% increase in the number of ethanol plants

marketing a DG coproduct with less than 10% fat. Additionally, there has been a 26%

increase in ethanol plants marketing DG coproducts with less than 7% fat. According to

the 2015 Ethanol Industry Outlook, 85% of dry-grind ethanol plants are removing corn

oil at some point in their processing (Renewable Fuels Association, 2015). In a process

known as back end oil extraction, thin stillage can be further centrifuged to remove

additional corn oil, resulting in a lower fat DG coproduct (U.S. Grains Council, 2012).

For front end oil extraction, the less common procedure, the grain source is fractionated

into endosperm, germ, and bran before fermentation (U.S. Grains Council, 2012). The

endosperm fraction then undergoes a traditional ethanol distillation process; whereas corn

oil is extracted from the germ fraction and the remaining germ meal and bran fraction are

utilized as feedstuff coproducts (U.S. Grains Council, 2012).

Feeding Distillers Grains

The 2015 Industry Outlook reported that in 2014, 43% of U.S. DG were

consumed by beef cattle and 30% by dairy cattle (Renewable Fuel Association, 2015).

Nearly three-fourths of all U. S. DG are consumed by ruminant animals due to their

innate capabilities to utilize a wide array of feedstuffs. Nutritionists utilize DG in many

forms as both sources of energy and protein. According to a 2007 consulting nutritionist

survey, 82.8% of the feedlot nutritionists surveyed, included grain coproducts in their

finishing diets (Vasconcelos and Galyean, 2007). Wet DG or DDGS were used as the

primary grain coproduct by 68.95% of nutritionists using grain coproducts (Vasconcelos

and Galyean, 2008).

Corn distillers grains. A large portion of starch is removed during distillation,

thus the remaining coproduct is concentrated with protein, fat, and fiber (Han and Liu,

2010). The moderately high CP of distillers coproducts warrant its use as a protein source

in ruminant diets. According to the NRC (1996), DDGS has an approximate CP content

of 30.4% and contains 52% rumen undegradable protein (RUP). Benton et al. (2006)

reported that DDGS RUP is approximately 90% digestible. Carrasco et al. (2014)

reported that ruminal digestion of feed N and N efficiency linearly decreased as DDGS

increased to 30%; however, total-tract digestion of N linearly increased as inclusion of

DDGS increased. Although direct amino acid utilization occurs, it was reported in a DG

review that DG have increased concentrations of amino acids but lower amino acid

digestibility compared with corn (Stein and Shurson, 2009).

Ham et al. (1994) compared either WDG or DDGS at 40% (DM basis) in diets

containing low, medium, or high ADIN. Sixty crossbred calves were fed to evaluate

protein source and efficiency and 160 yearling steers were fed to evaluate performance.

All calf diets were formulated for a minimum of 11.5% CP (DM basis) and urea was

included as the protein source in the control diet. As ADIN increased in DDGS, so did

the concentration of RUP; however, WDG had the highest RUP. Wet DG had the greatest

protein efficiency which was calculated as (gain above urea control divided by protein

intake above urea control). This can partially be attributed to the negative effect of

drying; as DG are dried, heat can bind nutrients, particularly protein (Lemenager et al.

2006). Yearling steers fed diets containing WDG had a lower DMI and greater G:F

regardless of the level of ADIN in DDGS (Ham et al., 1994). The WDG diet contained

39% more NEg and the DDGS diets contained 21% more NEg than the DRC control diet.

Larson et al. (1993) fed WDGS at levels up to 40% (DM basis) to calf-fed and yearling

steers consuming dry-rolled corn-based (DRC) diets. Both calf-fed and yearling studies

reported linear decreases in DMI and linear increases in G:F as WDGS inclusion level

increased. Both experiments also demonstrated a linear increase in diet NEg as

concentrations of WDGS increased.

Leupp et al. (2009) fed DDGS up to 60% (DM basis) to ruminally and duodenally

cannulated steers in 70% concentrate growing diet to determine the effect of increased

CP and DDGS inclusion on nutrient digestibility. Crude protein increased from 15% to

21.7% in the diet, with dietary CP tending to quadratically increase with a peak CP intake

at 45% DDGS inclusion. As DDGS inclusion increased, CP output decreased, total tract

CP digestion increased, with no differences for apparent ruminal, true ruminal, or

postruminal CP digestion. The authors indicate than this can be attributed to increased

digestion of N in the small intestine supported by the fact nearly half of more of DDGS

CP is RUP. Increased total tract digestion with increased DDGS inclusion supports

Carrasco et al. (2014); however, no difference in ruminal digestion contrasts.

Jenkins et al. (2011) fed additional RDP (urea) in both WDGS and DDGS diets to

determine if diets containing DG had sufficient RDP. In both the wet and dried

experiments, sufficient RDP was available without supplementing urea. Sufficient N

recycling occurred and MP was available thus supporting that DG can sufficiently supply

both RDP and RUP.

Trenkle (1996 and 1997) conducted 2 finishing experiments feeding cracked corn

with increasing concentrations of WDGS (16, 28, and 40%) and WDGS (20 and 40%) to

calf-fed steers and yearling steers, respectively. In both experiments, no live performance

differences were realized as concentrations of WDGS increased; however, in both

studies, the NEg content of WDGS was NEg 1.5 times greater than that of corn grain.

Mateo et al. (2004) fed steers 5 diets: corn:soybean meal control, 20% DDGS or WDGS,

and 40% DDGS or WDGS in cracked corn-based diets. Treatments containing WDGS

had greater G:F than DDGS, as well as greater G:F for steers fed 40% DG compared to

20%; this supports the earlier work of Ham et al. (1994) and Larson et al. (1993).

Vander Pol et al. (2006) fed increasing levels of WDGS, up to 50% (DM basis) to

yearling steers. The basal diet was a 50:50 blend of high-moisture corn (HMC) and DRC.

Quadratic responses were reported for DMI, ADG, G:F, and HCW, with the optimal

performance realized at a 40% inclusion of WDG. Corrigan et al. (2009a) evaluated corn

processing methods (steam-flaked corn (SFC), DRC, or HMC) and inclusion level of

WDGS (up to 40% DM basis). A corn processing by WDGS inclusion interaction were

reported for all live performance metrics. Dry matter intake responded quadratically

across all corn processing methods, reaching a peak at 15% inclusion and decreasing as

inclusion of WDGS increased. Average daily gain increased linearly across DRC

treatments; however, quadratic responses were reported within SFC and HMC treatments.

Hot carcass weight and G:F increased linearly as WDGS increased for DRC treatments,

and increased linearly at inclusions up to 27.5% WDGS for HMC treatments. Corn

processing methods directly influenced optimum inclusion levels of WDGS. Dry-rolled

corn treatments reached optimum numerical efficiency at 40% WDGS inclusion, HMC at

27.5% WDGS inclusion, and SFC at 15% WDGS inclusion. Buttrey et al. (2012) fed

heifers 0 or 20% WDGS (DM basis) in DRC or SFC-based finishing diets to determine

the interaction between corn processing and WDGS. In contrast to Corrigan et al.

(2009a), no interaction between WDGS inclusion level and corn processing was reported.

Regardless of WDGS inclusion level, SFC-based diets had decreased DMI and increased

G:F when compared with DRC. These results agree with the results of Nichols et al.

(2012) who fed WDGS at 0 or 35% in diets containing blends of SFC:DRC. These

authors indicated with increasing dietary inclusion of SFC, DMI decreased and G:F

increased, independent of WDGS inclusion.

Buckner et al. (2007) feed steers increasing levels of DDGS up to 50% (DM

basis) in DRC-based diets to determine optimum inclusion levels. Final BW was

quadratic with a maximum at 20% DDGS inclusion. Average daily gain and HCW tended

to respond quadratically, reaching peaks at 20% inclusion. Feed efficiency tended to

linearly increase as DDGS inclusion increased. In contrast, Vander Pol et al. (2006)

reported optimum feed efficiency by feeding 40% WDGS. Depenbusch et al. (2009) fed

heifers increasing levels of DDGS up to 75% (DM basis) in SFC-based diets. Similar to

the findings of Vander Pol et al. (2006), quadratic responses were reported for DMI and

ADG. In contrast, a linear decrease in G:F was reported with increasing DDGS inclusion.

It is noteworthy that although growth performance was reduced at inclusions greater than

15%, DMI, ADG, and G:F were similar for cattle fed 0 to 30% DDGS, and feeding 45%

DDGS or greater resulted in significant performance decreases. Hot carcass weight

followed similar patterns to growth performance, with the greatest HCW observed at

15% inclusion. The findings of Vander Pol et al. (2006) support the findings of Ham et

al. (1994) and Mateo et al. (2012), indicating greater performance for wet DGS than

dried. Increased feed efficiency of wet compared with DDGS is multi-factorial and can

be attributed to the negative effects drying has on protein and energy availability.

Optimum performance was reached at 30% of WDGS Vander Pol et al. (2006); whereas

Buckner et al. (2007) and Depenbusch et al. (2009) observed lower optimum inclusion

rates 20% and 15% (DM basis) for DDGS, respectively.

The importance of roughage in ruminant diets is well-known; however, the

interactions between roughage level and DG and roughage source are not well

understood. May et al. (2010b) evaluated roughage levels and corn processing methods

in 2 experiments. In Exp. 1, heifers were fed a basal diet of SFC with 0% or 25% DDGS

and 5% or 15% corn silage. In. Exp. 2, heifers were fed the same inclusions of corn silage

and DDGS in DRC or SFC basal diets. Roughage level did not impact growth

performance in Exp. 1; however, steers fed diets without distillers had carcasses with

lower LM area, and increased yield grades 4 and 5. In Exp. 2, DMI was greater for steers

fed DRC, whereas G:F was greater for SFC. Final body weight and G:F increased at 15%

silage inclusion and 0% DDGS. In contrast to Exp. 1, final BW and DMI decreased with

a lower inclusion of silage; however, dressing percentage increased with lower silage

inclusion. Feed efficiency, ADG, and carcass quality was not negatively affected when

roughage level was decreased when DDGS was included at 25% in the diet.

Uwituze et al. (2010) fed heifers corn silage or alfalfa hay, and 0 or 25% DDGS

in SFC-based diets. Similar to May et al. (2010b), no DDGS inclusion and roughage

interaction was observed. Final BW and ADG were also lower for treatments including

DDGS. A decrease in DMI was reported for heifers fed alfalfa hay compared with corn

silage, however, other growth performance responses were not affected by roughage

source. These authors reported G:F was less when 25% DDGS were fed compared with

no DDGS, which agrees with Depenbusch et al. (2009). In agreement with Uwitzue et al.

(2010), Benton et al. (2015) also reported no differences in G:F due to source of

roughage.

The variability of cattle finishing performance when DG are fed may be attributed

in part to the inconsistency of processing of DG. Multiple studies have reported positive

growth performance with low to moderate inclusion levels of DDG; however,

inconsistencies in performance have been reported at high inclusion levels. Consistently,

feeding wet DG results in greater cattle performance than feeding similar levels of

Sorghum distillers grains. Feeding sorghum DG is not novel within beef

production, however it is not as extensively researched as feeding corn DG. As water

availability has become more limited in certain regions of the US, grain sorghum

production has become a potential alternative to corn. Both corn and grain sorghum

produce similar quantities of ethanol due to similar amounts of starch (Turhollow and

Heady, 1986). Accordingly, as grain sorghum production has continued to rise, so has

sorghum-based ethanol production, and the use of sorghum DG for cattle feeding.

Lodge et al. (1997) fed 160 yearling steers DRC-based diets without distillers or

40% sorghum WDG, WDGS, or DDGS to evaluate the feeding value of sorghum DG. No

differences were reported for DMI or ADG among treatments; however, G:F and NEg

were less for steers fed sorghum DDGS. Lower NEg for sorghum DDGS is consistent

with the corn studies of Ham et al. (1994), Larson et al. (1993), Trenkle (1996 and

19997), and Mateo et al. (2004).

Drouillard et al. (2005) evaluated the optimum inclusion level of sorghum WDGS

in SFC-based diets by feeding WDGS levels up to 40% to heifers. Average daily gain,

G:F, and NEg all responded quadratically, maximum ADG was reached at 8%, whereas

G:F and and NEg were optimized by feeding 16% WDGS. Dry matter intake decreased

linearly with increasing sorghum WDGS inclusion. As the proportion of sorghum WDGS

increased, YG 1 carcasses and LM area decreased linearly, and YG 3 carcasses increased

linearly.

In 2 studies conducted by Vasconcelos et al. (2007), sorghum WDGS were fed to

steers to evaluate performance. In Exp. 1, increasing levels of sorghum WDGS (up to

15%) were fed in SFC-based diets. In Exp 2, a control containing no DG and 3 treatments

with sorghum WDGS 10% (DM basis) and increasing levels of urea to determine effects

of supplementing additional RDP. Final BW, ADG, G:F, HCW, and LM area decreased

linearly as inclusion rate of sorghum WDGS increased in Exp. 1. In Exp. 2, final BW,

ADG, and G:F were greater for control than the average of the 3 treatments containing

sorghum WDGS, regardless of inclusion level of urea. Hot carcass weight, rib-fat

thickness, and YG were also greater for control compared with the average of the

sorghum WDGS treatments. In both experiments, increasing levels of sorghum DG

resulted in decreased performance and carcass quality. Performance was not improved

with increasing supplemental urea which is consistent with Jenkins et al. (2011).

May et al., (2008) fed heifers increasing levels of sorghum WDGS (0 to 40%) in

SFC-based diets. Dry matter intake decreased linearly as sorghum WDGS increased

within the diets. Quadratic responses were reported for ADG and G:F with optimum

growth performance observed by feeding 16% sorghum WDGS, which agrees with

Drouillard et al. (2005). These findings contrast Leibovich et al. (2007) in which positive

growth performance responses were not reported by feeding sorghum WDGS.

Leibovich et al. (2009) fed steers diets containing 0% or 15% sorghum WDGS in

DRC or SFC-based diets. Dry matter intake decreased and G:F increased for diets

containing SFC which is consistent with Buttrey et al. (2012) and Mateo et al. (2004).

Final BW, ADG, and G:F decreased with the inclusion of sorghum WDGS, and may be

attributed to a decrease in both NEm and NEg for the diets containing 15% sorghum

WDGS. A decrease in G:F with the inclusion of sorghum WDGS supports the findings of

Vasconcelos et al. (2007). Hot carcass weight decreased for steers fed diets including

sorghum WDGS; no other carcass traits were effected.

Corn versus sorghum distillers grains. Grain sorghum’s drought tolerance and

lower water requirement has resulted in an increase in the acres of production each year.

From 2010-2015, grain sorghum acres planted increased by 3.1 million (NASS, 2016).

Although corn is still the primary grain feedstuff and grain source for ethanol production,

a better understanding of the differences in feeding values between corn and sorghum

coproducts is apparent. Research has been conducted to quantify these differences,

although more extensive research is warranted.

Al-Suwaiegh et al. (2002) fed yearling steers diets containing 30% corn or

sorghum WDGS in DRC-based diets. Steers fed diets containing WDGS had greater

final BW, ADG, G:F, and NEg compared with control. Dry matter intake was greater for

steers fed sorghum WDGS; however, G:F did not differ by grain source. In contrast,

Vasconcelos and Galyean (2007) reported no DMI differences between corn and

sorghum WDGS fed at 10%.

Depenbusch et al. (2009), fed yearling steers to compare the inclusion of DG at

15% (DM basis) with varying levels of roughage. Treatments were no DGS, sorghum

WDGS with 0 or 6% alfalfa hay, sorghum DDGS with 0 or 6% alfalfa hay, corn WDGS

with 6% alfalfa hay, or corn DDGS with 6% alfalfa hay. When sorghum wet or dried

DGS (6% alfalfa hay) treatments were compared to wet or dried corn DGS, no

performance differences were reported. Additionally, performance did not differ due to

physical form, which is inconsistent with Ham et al. (1994) and Mateo et al. (2004) both

of which reported increased performance for wet versus dried treatments. Final BW,

DMI, and ADG were greater for steers fed diets containing alfalfa hay at 6% regardless

of wet or dried sorghum DGS.

May et al. (2010a) fed corn, sorghum, or blended corn:sorghum WDGS at

increasing inclusion rates to evaluate differences in grain source and inclusion rates of

WDGS. Final BW decreased as WDGS inclusion rate increased from 15% to 30% and

G:F was greater for 15% WDGS, regardless of distillers type. Cattle fed blended

corn:sorghum WDGS diets had a lower DMI than cattle fed sorghum WDGS. Carcass-

adjusted G:F was greater for control than the average of all WDGS treatments.

Additionally, carcass-adjusted G:F was greater for corn WDGS than the average of

sorghum and blended treatments; 15% was greater than 30% inclusion. An interaction

among grain source by inclusion rate was reported for sorghum vs. blended, and was

attributed to the decrease in G:F when blended WDGS was fed at 30% compared with

15%. Net energy for gain was greater for blended corn:sorghum diets, and greater for

when DGS was fed at 15% than 30%, regardless of source.

Luebbe et al. (2012) fed increasing levels of blended corn:sorghum WDGS

(<15% sorghum grain). Final BW, ADG, and G:F decreased linearly as WDGS inclusion

increased. Dry matter intake responded quadratically with increasing WDGS levels, and

was greatest when 15 and 30% WDGS was fed. Hot carcass weight and fat thickness

decreased linearly as WDGS inclusion increased.

Considerable variability exists in DG feeding studies in regards to inclusion rate,

source, and physical form. Nevertheless, typically negative performance results are seen

as sorghum DG inclusion increases to a moderate or high inclusion. Decreased growth

performance is less common at low inclusion rates. On average wet DG performs better

than dried and corn better than sorghum; however, there are exceptions to both.

Deoiled distillers grains. As the ethanol distillation process continues to evolve,

ethanol coproducts continue to change as well. As previously described, additional corn

oil is being removed, changing the composition of the coproduct to contain less fat, and

research is limited with this altered coproduct.

Corrigan et al. (2009b) individually fed steers diets containing corn DDG at 0.25,

0.5, 0.75, or 1.0% of BW with proportions of condensed corn distillers solubles (CDS)

included at 0, 5.4, 14.5, 19.1, or 22.1% of DDG DM. Final BW, forage intake, DDG

intake, and total DMI intake increased linearly as DDG percent fed increased. Adding

CDS did not result in significant responses. Interactions were observed for both ADG and

G:F. A linear increase in ADG was reported for an inclusion of CDS at 5.4% and a

quadratic response in ADG was reported at a 22.1% CDS inclusion. Gain to feed

efficiency reported a linear increase at 5.4% CDS and a positive quadratic response at

14.5% CDS. As level of CDS increased so did the ether extract (6.9 to 13.3%). At greater

inclusion of DDG, the cattle were not able to maintain growth performance with the

increased CDS and subsequent dietary fat content.

To evaluate coproduct fat content, Pritchard et al. (2012) fed diets with no DG,

40% corn gluten feed corn DG blend, 40% corn WDG, and 40% corn WDGS to yearling

steers in a 50:50 DRC:HMC basal diet. Dietary fat content increased with increasing

DGS levels. Final BW, ADG, DMI, and G:F increased linearly with increasing dietary

fat content. Dressing percentage and HCW also linearly increased as dietary fat was

added. The resulting equation of diet NEg and dietary mean fat content regressions (NEg

= 57.32 + 1.02 (%EE)) suggested that a 1 Mcal change in NEg equates to a 1% change in

dietary fat. The authors suggest that this results in DGS fat with 2 times the NEg of the

replaced carbohydrate.

Bremer et al. (2015) fed yearling steers 8 diets to evaluate deoiled WDGS. Diets

contained deoiled WDGS at 0, 17.5, and 35% (DM basis) in SFC and DRC-based diets.

Two diets were fed that contained traditional (normal fat content) WDGS 35% (DM

basis) in SFC and DRC diets. No interactions between corn processing and concentration

of deoiled WDGS were reported. Final BW, ADG, G:F, and NEg linearly increased as the

concentration of deoiled WDGS increased. Hot carcass weight, fat thickness, and yield

grade all linearly increased as deoiled WDGS increased; marbling score responded

quadratically with maximum marbling peaking at 17.5% inclusion. No interaction was

reported between fat content of WDGS and corn processing methods. The only difference

reported for fat content of WDGS was an increase in NEg for traditional WDGS

compared to deoiled. Despite the decrease in WDGS fat content, the deoiled WDGS was

fed at increasing levels without negatively affecting growth performance.

Digestibility of distillers grains in finishing diets. Grain sorghum has 12.9%

lower NEg compared with corn, and can be attributed to structural differences in the

starch-protein matrix of the 2 grain sources (NRC, 1996; Rooney and Plugfelder, 1986).

Corn contains less peripheral endosperm, allowing the endosperm to be more readily

available for digestion (Rooney and Sullins, 1973; Rooney and Miller, 1982).

Additionally, it has been well-documented that the protein matrix surrounding the starch

within the endosperm of the two grains presents differences in digestibility (Riley, 1984;

Rooney and Pflugfelder, 1986; Wester et al., 1992). Two specific differences within the

protein-starch matrix are present among these 2 grains. Protein within the grain sorghum

endosperm is more tightly bound to the starch. Within the endosperm, prolamines are

cross-linked with kafirins, which decreases the digestibility of both the starch and protein

(Wall and Paulis, 1978; Hamaker, 1995). Further processing (steam-flaking, dry-rolling,

etc.) of both grains results in increased digestibility due to the breakdown of the protein

matrix, and the gelatinization of the starch (Rooney and Pflugfelder, 1986; Owens et al.

1997). The additional processing by the ethanol distillation process can result in ethanol

coproducts with improved digestibility. However, factors such as grain source,

processing methods, and inclusion rates of DGS impact nutrient digestibility and

utilization.

Lodge et al. (1997) fed wether lambs diets containing 80% (DM basis) corn or

sorghum WDG and corn or sorghum DDGS to determine the digestibility differences of

grain source and physical form of DGS. Apparent OM, apparent N, and true N

digestibility were greater for corn versus sorghum WDG. The WDG diets had greater

apparent OM, apparent N, and true N digestibility compared with dried. The improved N

digestibility of WDG supports the belief that drying binds protein and decreases

digestibility. The sorghum DDGS diets had greater apparent N and true N digestibility

than corn DDGS. Digestibility of NDF was not different among treatments.

May et al. (2010a) compared corn or sorghum WDGS at 15% (DM basis) in SFC-

based diets and a SFC diet with 0% DG. Crude protein and NDF intake increased with

the inclusion of distillers, regardless of source. No differences in apparent total-tract

nutrient digestibility were reported. Depenbusch et al. (2009) compared wet or dried

sorghum DGS to wet or dried corn DGS. No differences were reported for apparent total-

tract digestibility of DM or OM among grain source or physical form of DGS.

Cole et al. (2011) fed increasing proportions of blended corn:sorghum WDGS to

evaluate apparent nutrient digestion. Digestibility of DM and OM increased

quadratically. Luebbe et al. (2012) fed increasing concentrations of blended

corn:sorghum WDGS ( <15% sorghum grain) in SFC-based diets. Digestibility of

ruminal and total-tract OM linearly decreased with increasing concentrations of WDGS.

In contrast to OM, ruminal and total-tract NDF digestibility increased as concentration of

WDGS increased in the diets. Ruminal starch digestibility increased linearly with

increasing WDGS; however, total-tract starch digestibility responded quadratically, with

peak digestion at 15% inclusion.

Jolly-Breithaupt et al. (2015) conducted a study to analyze the digestibility of

diets containing deoiled CDS or deoiled modified DGS compared to traditional fat

coproducts. The basal diet was a 50:50 blend of DRC to HMC with deoiled or traditional

CDS at 27% or MDGS at 40%. No interactions between coproduct and fat were observed

for DM, OM, and NDF intakes or digestiblities. A coproduct by fat interaction occurred

for fat digestibility; traditional fat CDS (27%) had the greatest digestibility. No

differences were reported for fat digestibility for deoiled versus traditional fat MDGS.

However, deoiled CDS was less digestible than the traditional fat CDS and indicates

deoiling may have an effect the on the digestibility of the fat depending on the type of

coproduct.

History of Palm Kernel

African oil palm, (Elaeis guineensis Jacq.) is a popular and growing industry in

many tropical regions. The history of the oil palm is extensive and dates back thousands

of years. In 1790, the first recorded palm oil was imported into the UK, cultivation as a

commercial crop began in West Africa in 1807, the first mechanized mill was constructed

in West Africa in 1909, and by 2004, palm oil was the world’s largest source of vegetable

oil (Henson, 2012). It is typically grown in Africa, South-east Asia, and South America

but has continued to expand into Central America (Henson, 2012). Oil palm is typically

grown in groves or plantations, with an increasing number of small farmers growing oil

palm due to government subsidization (Henson, 2012). Oil is extracted from both the

outer mesocarp and inner nut, producing palm oil and palm kernel oil, respectively. The

extraction of oil results in biomass that is commonly used in both the bioenergy industries

and the livestock industry. Palm kernel meal (PKM), also known as palm kernel cake

(PKC), is a byproduct of the extraction of palm kernel oil and is used as a feedstuff in

livestock production. Production of PKM was just under 5 million tonnes in 2013 (FAO,

2015).

Palm Kernel Processing

The inner nut of the oil palm contains a hard outer shell and an inner kernel

(Obibuzor et al., 2012). The outer shell is cracked and separated from the kernel. Oil is

removed from the kernel by screw press or solvent extraction. After the outer shell is

separated from the kernel, the kernel is dried. The dried kernel is then ground to a smaller

particle size, heated “cooked”, and the oil is removed. In the screw press method an

oilseed expeller is utilized and in the solvent extraction a petroleum based solvent is

added, sometimes both of these methods are used in conjunction with each other

(Obibuzor et al., 2012). There are advantages to both processes. More oil is removed via

solvent extraction; however, the cost is greater and the public perception is worse. After

removal of the oil, the remaining kernel particles are now known as PKM or PKC

(Obibuzor et al., 2012).

Feeding Palm Kernel Meal to Livestock

Due to the fibrous nature of PKM it is commonly fed to ruminants, but has also

been utilized in swine and poultry diets (Zahari and Alimon, 2003). The method of oil

extraction can have an impact on the composition of PKM, but it is generally regarded as

a high fiber, moderate protein and energy source (Alimon, 2005). On a DM basis, CP

ranges from 14.5 - 19.6%, ether extract 5.0 - 8.0%, and NDF 66.8 – 78.9% (Alimon,

2005). O’Mara et al. (1999) analyzed the chemical composition and digestibility of

expeller and solvent extracted palm kernel meal samples using wether lambs. Organic

matter and CP were more digestible for solvent extracted samples. Although solvent

extracted samples contained greater amounts of crude fiber and NDF, there was no

difference in NDF digestibility between processing methods. The authors attribute a

greater fiber content in solvent extracted samples due to an ether extract dilution effect

(O’Mara, 1999). No differences in digestible energy or gross energy were reported.

Limited growth performance data for ruminant animals fed diets containing PKM

exists. In a PKC review, it was reported that Sahiwal-Friesian cattle were fed diets

containing solvent extracted or expeller pressed PKC at 50:50 ratio with dried sago pith;

no differences in performance were reported for the 2 diets (Chin, 2001). Sago pith is a

byproduct of sago palm (Metroxylon sagu) and a highly digestible carbohydrate

(Chanjula and Ngamponsai, 2009). Abdullah and Hutagalung (1987) fed a PKC-based

diet (63.1% PKC-solvent, 25.9% PKC-expeller, 5.0% corn, and 3.0% fishmeal). The

analyzed diet contained 16.6% CP. Eight bulls and 8 females were fed for 185 days, no

palatability issues or digestive upset problems were encountered. Dressing percentages

were similar for both males and females (58%). Rumen fermentation was analyzed on 4

bulls and 4 females. The pH and VFA concentrations were considered desirable

(increased proprionate and decreased acetate). The authors noted that both males and

females had completely defaunated rumens. The research of Mohamed and Alimon

(2003) reported that in Malaysia typical finishing diets contain between 50 – 80% PKC.

At 80% inclusion of PKM crossbred cattle can gain 1-1.2 kg/d. Positive performance

when feeding high levels of PKM is possible; however, little is known about the true

feeding value and digestibility of diets containing PKM.

Conclusions

Despite the extensive research that has been conducted feeding DG to ruminant

animals, the inherent variability of DG has resulted in extensive variability of results. On

average, positive performance and carcass results have been reported at greater inclusions

of corn than sorghum and wet than dried. Nevertheless, lower inclusion rates have been

able to mitigate differences due to source and physical form. Digestion of nutrients is

effected by inclusion and source with corn DG classically being more digestible due to

the physical differences of the grain sources. Deoiled coproducts have reported positive

performance with limited digestibility differences beyond fat. In contrast to the extensive

DG research, far less information is known about PKM. Nevertheless, PKM is a major

component in the diets of ruminants in other countries. Upon review of the literature, it is

evident that further research needs to be conducted on the differences in DG source, corn

versus sorghum and more information collected on feeding PKM.

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CHAPTER III

THE RELATIONSHIP BETWEEN CROP WATER USE AND FINISHING

PERFORMANCE OF BEEF STEERS FED DIETS CONTAINING CORN OR

SORGHUM DISTILLERS COPRODUCTS

ABSTRACT

Feedlot steers were fed diets containing 25% (DM basis) corn dried, sorghum

dried, or sorghum wet distillers grains with solubles (DGS) in a previously conducted

study, with G:F for corn DGS = 0.153, and sorghum wet DGS = 0.150, and sorghum

dried DGS = 0.142. These G:F ratios were combined with crop yield and crop water

(effective precipitation, irrigation, and soil moisture) data collected over a 10-yr period

by the Texas Alliance for Water Conservation project (Hale and Floyd counties in

southern Texas High Plains region) to develop an equation for water use efficiency of

beef production. The relationships between crop grain yield and crop water use were

determined using quadratic regressions. Crop yield-to-water ratios (kg/m3) were

calculated using predicted yields. Distillers grain-to-water ratios were calculated using a

grain to DGS conversion factor (GDG). To account for crop water requirement of the

DGS portion of the grain, total crop water was multiplied by 0.33. The DGS:water ratio

was adjusted for the DM of DGS source, yielding a value expressed in kg of DGS/m3 of

crop water. The DGS contribution to gain (DC%) was accounted for by using diet NEg

and DGS NEg values; G:F was adjusted by DC% to reflect kg of beef gain from DGS.

The DGS G:F was divided by the DGS:water ratio to determine the water use efficiency

of beef production credited to the DGS as kg of beef/m3 crop water. Water Use

Efficiency of Beef Production = {(𝐷𝐶%)𝑥 𝐺: 𝐹} ÷ ⟦{(𝑘𝑔 𝐺𝑟𝑎𝑖𝑛

𝑚3 𝑊𝑎𝑡𝑒𝑟 𝑥 0.33) ÷ 𝐺𝐷𝐺} ×

𝐷𝐺𝑆 𝐷𝑀⟧. Overall, corn had greater crop water inputs than grain sorghum, and reached a

peak yield of 17,324 kg/ha at 768 mm of water input, when calculated from the quadratic

fitted equation. Grain sorghum yields were similar to corn yields at the low end of the

observed water input range. At a water supply of 197 mm, a maximum water use

efficiency for beef production was reached at 0.089 kg/m3 for sorghum wet DGS and

0.073 kg/m3 for sorghum dried DGS. Corn DGS reached its peak efficiency at 286 mm of

crop water, with a water use efficiency for beef production of 0.092 kg/m3. Sorghum

DGS have the potential to produce beef as efficiently as corn DGS at low water inputs,

reflective of dryland conditions, in which corn would not be productive. The greater feed

efficiency of wet sorghum DGS compared to dried DGS can translate into greater water

use efficiency for beef production feeding sorghum wet DGS than dried DGS. As

reduced pumping capacity from the declining Ogallala aquifer restricts crop irrigation on

the Texas High Plains, measuring efficiency of beef production from low-water input

crops and their coproducts becomes increasingly important.

INTRODUCTION

Corn is the predominant ingredient in the U.S. cattle feeding industry because of

its favorable energy value in finishing diets. Yet, in semi-arid regions, like the Texas

High Plains (THP), where cattle finishing is heavily concentrated, local production of

sufficient quantities of corn is limited by water availability. Discovery of the Ogallala

aquifer in the THP transformed the landscape from a native short-grass prairie to

intensive row-crop production. Over time, this resource has declined in capacity due to

heavy crop water demands and frequent periods of drought and drought-like conditions.

For example, measurable declines have been observed in the southern portion of the

THP, as the water level declined by 3.13 m from 2005 to 2015 (HPWD, 2015). Grain

sorghum generally exhibits greater water use efficiency and lower crop water

requirement than corn under low-water-input conditions (Assefa et al., 2014; Stone and

Schlege, 2006). Grain sorghum offers an opportunity for enhanced feed grain production

over corn in areas that irrigation water supply is declining. Stone and Schlegel (2006)

reported greater water use efficiency at evapotranspiration (ET) values above 537 mm for

corn and below 537 mm for grain sorghum. In a 6-year Texas study with varying growing

season lengths, grain sorghum used an average of 193 mm less ET over a consistently

shorter growing season than corn (Howell et al., 1997).

Despite drought tolerance of grain sorghum, the differences in feeding values

between grain sorghum and corn still exist. Grain sorghum has a 12.9% lower NEg

compared with corn, which can be attributed to structural differences in the starch-protein

matrix of the two grains (NRC, 1996; Rooney and Plugfelder, 1986). Opheim et al.

(2016) fed 25% (DM basis) corn dried and sorghum wet or dried DGS in steam-flaked

based diets to beef finishing steers. Steers fed diets with corn dried DGS had greater G:F

and apparent digestibility of nutrients compared with steers fed diets with sorghum DGS.

Thus, the objective of this study was to define the relationship between crop water

requirements and differences in feed efficiencies of corn and grain sorghum DGS in diets

for finishing cattle.

MATERIALS AND METHODS

Beef Efficiency

In a study conducted at the Texas Tech University Burnett Center, crossbred

steers were fed to evaluate feedlot cattle performance and apparent total tract nutrient

digestibility of finishing diets containing corn and sorghum coproducts. Dietary

treatments were: 1) corn dried DGS (DRY-C); 2) sorghum dried DGS (DRY-S); and 3)

sorghum wet DGS (WET-S) (Table 3.1). Diets were balanced for CP and ether extract

and coproducts were included at 25% (DM basis; Opheim et al., 2016). Coproduct DM,

G:F, and NEg values from this study were utilized in the current analysis (Table 3.2).

Crop Water Use Efficiency

Data from Texas Alliance for Water Conservation (TAWC; TAWC, 2015) were

used to develop yield and water production functions. The Alliance TAWC is a

partnership of universities, government agencies, industries, and producers seeking to

conserve groundwater use for irrigation by using crop water-monitoring technology and

advanced irrigation practices. The data set consisted of actual farm data collected from

2005 to 2014 from 29 cooperating farms in Hale and Floyd counties in Texas. Various

cropping systems managed by 20 producers included multi-crop, monoculture, and

integrated crop-livestock systems. Crops within systems included cotton, corn, sorghum,

perennial forage, small grains, perennial grass seed, peanut, and sunflower. For the

purpose of this analysis, only corn and grain sorghum data were used (Tables A-1 & A-

Grain type and intended purpose (grain or silage), irrigation type (e.g. sprinkler

vs. subsurface drip) and quantity of water applied, rainfall, soil moisture changes, yield,

and cost and type of inputs were recorded from each site (TAWC, 2015). All sites that

reported corn and grain sorghum (harvested for grain) data from 2005-2014 were

included in the current analysis and included all irrigation systems and management

practices. Sites that were not representative of harvested grain were removed from the

analysis (sites that claimed insurance, sites that did not harvest, and sites that replanted an

alternative crop after initial crop failure).

Grain yield responses (in kg per hectare) to crop water input (in mm) were fitted

to quadratic functions and plotted for comparison (Figure 3.1). Total crop water input

comprised the sum of effective rainfall, seasonal irrigation, and changes in volumetric

soil moisture content. Rainfall was calculated as 50% effective for this analysis based on

guidelines for this region from USDA Natural Resources Conservation Service (TAWC,

2015). Rainfall was measured with custom-designed rain gauges by personnel of the

High Plains Underground Water Conservation District. All grain yield data were reported

at 15% moisture.

Water Use Efficiency of Beef Production

Predicted yields from the regressions were expressed as crop water use efficiency

by dividing kilogram of grain by the associated hectare-millimeter, and then converting

hectare-millimeter units to cubic meters by dividing kg of grain by 10. Grain mass values

were converted to kilograms of DGS (dried and wet) using a grain to distillers grain

conversion factor (GDG). The GDG was 3.11 for dried and 1.14 for wet (25.4 kg of grain

= 8.2 kg dried DGS or 22.2 kg wet DGS) (Duff, 2015, United Sorghum Checkoff

Program, Lubbock, TX, personal communication). It should be understood that the

volume of crop water reported reflects the water required to produce the grain. Therefore,

to calculate the crop water needed to produce DGS, the volume of water was multiplied

by 0.33 to accurately reflect the water contribution. The DGS:water values reflect the

kilograms of corn or sorghum, dried or wet DGS produced by 1 cubic meter of crop

water on an as-is basis. These values were further converted to a DM basis using the

analyzed average DM of each DGS (Table 3.2). The DGS:water efficiency defines the

kilograms of DGS on a DM basis produced by 1 cubic meter of crop water.

Gain to feed efficiency assesses kilograms of beef gained to kilogram of feed

(feed representing a kilogram of the total diet). Although coproducts were included at

25% (DM basis) of the diet, they do not directly represent 25% of the G:F. In order to

assess the coproducts’ contribution of gain, adjustments were made to the base

percentage or inclusion rate of 25%. Using an equation derived by Pritchard et al. (2012)

[(Test NEg - Control NEg) / % coproduct] + 1.496, the NEg for corn dried, corn/sorghum

dried, and sorghum dried and wet coproducts were calculated. The original equation

included 1.496 Mcal/kg to reflect a 50:50 dry rolled corn:high moisture corn blend, and

was adjusted to 1.562 Mcal/kg to reflect the steam-flaked corn used in the present feeding

experiment. The DGS contribution percentage (DC%) was calculated with the following

equation (Table 2). {(

𝑇𝑒𝑠𝑡 𝑁𝐸𝑔 – 𝐶𝑜𝑛𝑡𝑟𝑜𝑙 𝑁𝐸𝑔

0.25)+1.562} ×0.25

𝐷𝑖𝑒𝑡 𝑁𝐸𝑔= DC %

Coproducts with greater energy concentration contributed more to gain, and

coproducts with less energy contributed less, reflecting the energy differences of the

grain sources and the impact of processing. Corn dried DGS, sorghum wet DGS, and

sorghum dried DGS feed efficiencies from the finishing study were multiplied by the

DC% to reflect the feed efficiency of the DGS (Table 3.2). The inverse of the DGS gain

efficiencies were divided by the respective DGS:water efficiencies. Recalculating the

efficiency values as their inverse resulted in expression of a water footprint of beef

production (cubic meters of crop water used to produce 1 kilogram of beef). The

equations were the following:

Water Use Efficiency of Beef Production =

{(𝐷𝐶%)𝑥 𝐺: 𝐹} ÷ ⟦{(𝑘𝑔 𝐺𝑟𝑎𝑖𝑛

𝑚3 𝑊𝑎𝑡𝑒𝑟 𝑥 0.33) ÷ 𝐺𝐷𝐺} × 𝐷𝐺𝑆 𝐷𝑀⟧

Statistical Analyses

Water and yield data were analyzed using the REG procedure of SAS (SAS Inst.

Inc., Cary, NC) using a quadratic model.

RESULTS AND DISCUSSION

When DGS was included at 25% (DM basis) in steam-flaked corn-based diets,

feed efficiency differences were reported (Opheim et al., 2016). The diet G:F of DRY-C

and WET-S were similar (P > 0.45); whereas DRY-C was greater than DRY-S (P < 0.01)

(Opheim et al., 2016). Differences in efficiency can be attributed to apparent digestibility

differences of the diets. The DM and OM digestibilities of the WET-S diet were similar

to the DRY-C (P > 0.30) and greater than the DRY-S diet (P < 0.01) (Opheim et al.,

2016). The WET-S diet had greater NDF, ADF, and hemicellulose digestibility than both

DRY-C and DRY-S (P < 0.01) (Opheim et al., 2016). Crude protein digestibility was

greatest for DRY-C, followed by WET-S and DRY-S (P < 0.01). Ether extract and starch

were similar for DRY-C and WET-S (P > 0.09) (Opheim et al., 2016). At a lower

inclusion, 15% (DM basis) DGS, in a steam-flaked corn-based diet, no digestibility

differences were reported for corn and sorghum dried DGS (Depenbusch et al., 2009).

The digestibility differences reported for greater DGS inclusions alludes to distinct

digestibility differences remaining between corn and grain sorghum, even after ethanol

distillation.

Corn and grain sorghum have inherent digestibility differences. Grain sorghum

contains more peripheral endosperm, which makes the endosperm less available for

digestion (Rooney and Sullins, 1973; Rooney and Miller, 1982). Differences in the

protein matrix surrounding the starch within the endosperm also inhibits digestion (Riley,

1984; Rooney and Pflugfelder, 1986; Wester et al., 1992). Corn and grain sorghum store

different forms of prolamines as their primary storage protein; total corn protein is

composed of 50-60% zein, whereas 68-72% the total protein in grain sorghum is kafirin

(Hamaker, 1995). Extensive crosslinks within kafirn reduce protein digestibility (Belton

et al., 2006). Additionally, the protein within the grain sorghum endosperm is more

tightly bound to the starch, thus decreasing digestibility of both the starch and protein

(Wall and Paulis, 1978; Hamaker, 1995). Herold et al. (1999) reported that the protein

contained within the solubles portion of distillers grains was composed primarily of

yeast, which was approximately 20% degradable in the rumen. McDonald et al. (1954)

reported that zein was nearly 40% degradable in the rumen. Further processing (steam-

flaking, dry rolling, etc.) of both grains results in increased digestibility due to the break-

down of the protein matrix and starch gelatinization (Hale, 1973).

Not only are there differences in the feed efficiency caused by the physical nature

of the two grains, but there are also distinct crop water input differences. The mean water

input for corn was 647 mm and the mean grain yield was 12,483 kg/ha. The same values

for grain sorghum were 456 mm and 7,176 kg/ha, respectively. The crop water inputs of

corn production are generally greater than grain sorghum as depicted in greater levels of

water input for corn in Figure 3.1, reflecting the preferred use of corn when irrigation is

ample. The fitted quadratic response function for corn indicated a peak yield of 17,324

kg/ha at 768 mm of water input. The response function for grain sorghum did not reach a

peak. Corn exhibited greater grain yield than grain sorghum at a given water input as corn

yields approached the optimum, indicating high water use efficiency. At lower water

inputs, corn and grain sorghum produced similar yields, yet as water input increased, corn

out-yielded grain sorghum. Grain sorghum can handle soil water deficit better than corn

due to deeper and denser root structure, self-pollination, and plasticity during the growing

phase (Assefa et al., 2014). In the TAWC data, the corn and grain sorghum yields

converged at approximately 300 mm of total crop water applied and at approximately

6500 kg grain/ha (Figure 3.1). Lack of corn yield data at the lower end of water input

prevents expression of a crossing over of the two crop functions with respect to water use

efficiency. Corn is generally considered less capable than sorghum to produce

harvestable grain at low water input (Assefa et al., 2014), which indicates an advantage

for sorghum production when water supply is low. High corn yield is possible when the

water input is substantially increased beyond 300 mm. The TAWC data highlight the

current and distinctly different management strategies used by corn and grain sorghum

producers in the Texas High Plains region. Corn producers apply irrigation at rates that

far exceed the water applied to grain sorghum, noted by the nearly 400 mm of water

difference between the ends of the corn and sorghum curves (Figure 3.1). Some

producers also applied water at rates beyond 100% the crop water demand (potential ET

rate of the field) (TAWC, 2015). As water application increases beyond the plant’s needs,

yields begin to decline resulting in inefficient production, decreased economic returns,

and unsustainable use of resources. Rainfall, irrigation type and management, climate,

soil, length of growing season, and several other factors contribute to the differences

between yield and water relationships.

When modeled using the TAWC crop-water response functions, beef

production with sorghum wet DGS was as efficient as that from corn dried DGS at the

lowest water input observed (Figure 3.2). As water input increased, the efficiency of both

crop DGS sources declined, with that of grain sorghum declining more steeply than that

of corn. Sorghum DGS most efficiently produced beef at the lowest water application

observed (197 mm), with water use efficiencies of 0.089 kg/m3 and 0.073 kg/m3 for

sorghum wet DGS and sorghum dried DGS, respectively. Corn DGS was also most

efficient at its lowest input of water (286 mm), with a water use efficiency of 0.092

kg/m3. Again, lack of sufficient data at the lower end of water input prevents a precise

identification of a trade-off in corn vs. sorghum under very limited water inputs. The

trends do suggest that feeding sorghum DGS under dryland cropping conditions results in

a high water use efficiency for beef production. Similar to the TAWC yield response

curve (Figure 3.1), the efficiency of beef produced from corn DGS declined as water

application reached beyond plant needs. Several factors contribute to excessive

application of water. Unpredictable rainfall and weather are both continually faced in

irrigation management; for example, rainfall received directly after irrigation can create

over-application of water. Additionally, poor irrigation management practices and

irrigation systems having greater evaporation can also create unnecessary water

application.

The results indicate that feeding corn DGS to beef cattle results in more efficient

crop water use in scenarios with medium to high water use situations, and that

efficiencies of dried and wet sorghum DGS can approach those of corn DGS at low water

inputs. Two factors that drive greater water use efficiency are crop yield potential and

increased digestibility of corn. With medium to high water application, corn yield was

nearly double that of grain sorghum (Figure 3.2). Tollenaar and Lee (2002) credited the

increased yield potential of corn to genetic improvement, agronomic-management

improvement, and favorable genotype x management interactions. Factors also

contributing to increased corn yields include widespread adaptation of improved hybrids,

selection for tolerance of stressors (low soil moisture or N, tolerance to high planting

density, weed interference), enhanced photosynthetic efficiency, and the dynamic

potential of genotypes to adapt to environmental changes (Tollenaar and Lee, 2002).

Precision agriculture technologies have also had significant positive impacts on yields

(Nielsen, 2012). Although many of these factors have contributed to improvements in

grain sorghum yields as well, physiological profit-potential differences between corn and

grain sorghum have resulted in faster improvement in yield of corn. If corn receives

adequate water, it is a consistently able to grow taller and produce more leaves, which

allow the plant to capture more radiation and convert it into greater yield (Aseefa et al.,

2014).

IMPLICATIONS

The novel analysis in the present study combined crop production and beef

production to discover possible tradeoffs between the two grain sources. Differences in

yield potentials between corn and grain sorghum, coupled with differences in

digestibility, magnified greater water use efficiency of corn DGS in beef production in

medium to high water input situations. Nevertheless, those differences were narrowed in

low water-input situations, possibly making grain sorghum more water use efficient

under dryland conditions. The importance of water use and production efficiency will

continue to grow as water use restrictions increase and greater emphasis is placed on

sustainable practices and measurements.

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Chem., St. Paul, MN. p. 135-219.

Wester, T. J., S. M. Gramlich, R. A. Britton, and R. A. Stock. 1992. Effect of grain

sorghum hybrid on in vitro rate of starch disappearance and finishing performance

of ruminants. J.Anim. Sci. 70:2866. doi:/1992.7092866x.

Table 3.1. Ingredient composition of corn and sorghum coproduct diets fed to beef steers*

Treatment1

Item DRY-C WET-S DRY-S

Ingredient, %

Steam-flaked corn 59.68 61.93 59.45

Corn dry DGS 25.00 -- --

Corn/sorghum dry DGS -- -- --

Sorghum dry DGS -- -- 25.00

Sorghum wet DGS -- 25.00 --

Cottonseed hulls 4.00 4.00 4.00

Alfalfa hay 4.00 4.00 4.00

Molasses 3.00 -- 3.00

Supplement2 2.00 2.00 2.00

Fat (yellow grease) -- 0.79 1.25

Limestone 1.80 1.10 1.30

Urea 0.52 0.49 -- 1DRY-C = 25% (DM basis) inclusion of corn dried distillers grains with solubles (DGS); DRY-S = 25% (DM basis)

inclusion of sorghum dried DGS; and WET-S = 25% (DM basis) inclusion of sorghum wet DGS. 2Supplement contained (DM basis): 71.514% ground corn, 0.500% antioxidant (Endox, Kemin Industries, Des

Moines, IA), 10.000% potassium chloride, 15.000% salt, 0.002% cobalt carbonate, 0.196% copper sulfate, 0.083%

iron sulfate, 0.003% ethylenediamine dihydroiodide, 0.167% manganous oxide, 0.125% selenium premix (0.2%

Se), 0.9859% zinc sulfate, 0.009% vitamin A (1,000,000 IU/g), 0.157% vitamin E (500 IU/g), 0.750% Rumensin

(220.5 mg/kg monensin, Elanco Animal Health, Indianapolis, IN), 0.506% Tylan (97 mg/kg tylosin, Elanco Animal

Health).

*Adapted from Opheim et al. (2016)

Table 3.2. Conversion factors and calculated values

Treatment1

Item DRY-C WET-S DRY-S

Diet NEg, Mcal/kg of DM2 1.31 1.28 1.25

DGS NEg, Mcal/kg of DM3 1.40 1.28 1.16

DGS Contribution %4 26.76 25.04 23.24

Diet G:F5 0.153 0.150 0.142

DGS G:F6 0.041 0.038 0.033

DGS DM %7 88.8 34.6 89.4 1DRY-C = 25% (DM basis) inclusion of corn dried distillers grains with solubles (DGS); DRY-S = 25% (DM basis)

inclusion of sorghum dried DGS; and WET-S = 25% (DM basis) inclusion of sorghum wet DGS. 2Dietary NE values were calculated from performance data (Opheim et al. 2016) using NE equations (NRC, 1996)

and methods of Vasconcelos and Galyean (2008). 3DGS NE values were calculated using DGS NE equation Pritchard et al. (2012). 4Calculated [DGS NEg x 0.25 (inclusion rate)] / Diet NEg 5Opheim et al. (2016). 6 DGS Contribution % x G:F 7DM for DGS were analyzed throughout finishing period.

02000400060008000

100001200014000160001800020000

0 200 400 600 800 1000 1200

Crop water input (mm)

Grain Sorghum Corn

Figure 3.1. Yield response to water input. W= (total irrigation + effective rainfall + soil moisture).

Corn Y = -2403+ 42.3 (W) - 0.028 (W2) R² = 0.22 Grain Sorghum Y = 2664 + 13.1 (W) -0.006 (W2) R² = 0.39

Figure 3.2. Water use efficiency of beef production.

Water Use Efficiency of Beef Production = {(𝐷𝐶%)𝑥 𝐺: 𝐹} ÷ ⟦{(𝑘𝑔 𝐺𝑟𝑎𝑖𝑛

𝑚3 𝑊𝑎𝑡𝑒𝑟 𝑥 0.33) ÷ 𝐺𝐷𝐺} × 𝐷𝐺𝑆 𝐷𝑀⟧

DC% = distillers grain contribution percentage.

G:F = kg gain/kg diet DMI.

GDG = grain to distiller grain 3.11 for dried and 1.14 for wet (25.4 kg of grain = 8.2 kg dried DGS or 22.2 kg wet DGS).

DGS DM = coproduct DM.

00.010.020.030.040.050.060.070.080.09

0 200 400 600 800 1000 1200

Crop water input (mm)

Corn Dried Distillers Grain Sorghum Dried Distillers Grain Sorghum Wet Distillers Grain

CHAPTER IV

UTILIZATION OF LOCAL BYPRODUCTS IN BEEF FINISHING DIETS IN

HONDURAS: DESCRIPTIVE ASSESSMENT OF GROWTH PERFORMANCE

AND CARCASS CHARACTERISTICS

ABSTRACT

Five finishing diets were formulated using local Honduran feedstuffs such as

palm kernel meal (PKM), poultry litter (PL), and sugar cane (SC) for bulls in

confinement. Diets were formulated on DM basis and targeted 13.5% CP. Each

experiment was identified, Honduran Management (HM) 1-5; treatments HM1, HM2,

and HM3 were fed in the central region of Honduras, HM4 the southeast, and HM5 the

northwest. All cattle were Bos indicus influenced crossed with Bos taurus and dairy type.

Bulls were fed between 74-165 d with an average of 100 d. Initial BW ranged from 305-

443 kg with an average of 369. Cattle were fed to a minimum end point of 400 kg

unshrunk live final BW). Growth performance and carcass characteristics were analyzed

using the PROC UNIVARIATE procedure of SAS (9.4 Inst. Inc., Cary, NC).

Considering all diets, dry matter intake ranged from 8.75 to 13.00 kg/d with an

average of 10.81 kg/d; DMI increased with inclusion of roughage. Average daily gain

ranged from 0.84 to 1.31 kg with an average of 1.08 kg; ADG increased for those diets

with greater inclusions of corn. Final BW averaged 487 kg with a modest variability (CV

= 7.90%). Gain to feed followed similarly to ADG; diets with greater energy were more

efficient. Hot carcass weight ranged from 250 to 301 kg with an average of 264 kg. The

dressing percent interval ranged from 54.03% to 58.01% with low variability (CV =

2.81%). The LM area and marbling score reported low variability (CV < 8%) with

averages of 28.03 cm2 and 289, respectively. The 12th-rib back fat averaged 5.15mm

ranging from 3.82 to 6.54 mm. Feed cost of gain ranged from $0.40 to $0.67/kg with an

average of $0.53/kg; FCOG was lower in the central region. All diets were viable options

for Honduran producers to finish beef cattle depending on feedstuff or byproduct

availability. Local byproducts can effectively be blended with other feedstuffs to reach

sufficient protein and energy, demonstrating the role byproducts can have within

Honduran beef finishing systems. Dressing percent driven by carcass weight was one of

the most important factors affecting profitability. Subsequently, this preliminary

information can be utilized to conduct more intensive research on local feedstuffs and

diets across Honduras.

INTRODUCTION

Agriculture is important to economies of developing countries such as Honduras.

Forty-six percent of the Honduran population resides in rural areas; 60% of rural

employment and 38% of total employment is based-on agriculture (World Bank, 2014).

Even with a large number of people contributing to agriculture within the country,

problems within the agriculture sector continue to persist, particularly within the beef

industry. Beef production in Honduras reached surplus levels in the 1980’s, with peak

export volumes of 13.0 thousand tonnes from 1993-1995 (FAO, 2003). Natural disasters,

economic downturns, and sale of live cattle to neighboring countries (high feeder cattle

prices) led to a sharp decline in beef production with only 1.3 thousand tonnes of beef

exported during 1998-2000 (FAO, 2003). Such decreases in beef export numbers are

also reflected by the shortness in local beef availability in the country, which drives the

high internal beef prices. In addition, current beef production practices are based on

pasture resources, requiring long cycles (30 to 36 months until harvesting), and do not

take advantage of several local feedstuff byproducts currently available. Beef is an

important commodity in Honduras to feed the population, as well as an important

economic resource. Honduras is one of the few countries in Central America approved by

the USDA-FSIS to export beef to the US and thus could be an important trade

commodity, although none is currently being exported to the US due mainly to the lack of

beef production.

The overall objective of this study was to assist in the revitalization of the

Honduran cattle industry through: 1) the development of more sustainable diets for beef

cattle derived from locally available byproducts in Honduras; 2) the creation of descript

analyses of such diet options effects on overall cattle growth performance and carcass

characteristics; and 3) the assessment of critical points for improvement of feedlot

industry in Honduras. We hypothesized that by balancing finishing diets at 13.5% CP and

increasing diet energy content, in combination with improved management practices and

targeting a greater final BW, we would be able to improve growth performance and

increase carcass weight.

MATERIALS AND METHODS

All experimental procedures were conducted in accordance with an approved

Texas Tech University Animal Care and Use Committee (Protocol # 14071-09).

Approach

In 2012, faculty from Texas Tech University realized the opportunity for

improved beef production in Honduras and began working with Agriculture School of

Zamarano, Honduran National Agriculture University, Honduran cattle producers, and

Honduran cattle organizations. Faculty were approached due to a drastic decline in cattle

herd within the country and the need to identify sustainable feed sources for cattle.

Initially, the team focused on meat science and food safety; however, the scope expanded

to ruminant nutrition when it was evident there was a pronounced need for improved beef

cattle nutrition. The importance of protein for humans and animals, and the decline in

beef production in Honduras outlined the project goals. The resulting focus was to

enhance beef production in Honduras by developing economically-efficient, balanced

diets based-on locally available byproduct feedstuffs, in conjunction with improving

management practices in existing systems.

In 2014, Texas Tech team members (faculty and staff) visited Honduran ranches

to implement experimental diets and experimental production management strategies.

Locations were selected by willingness to participate, interest in improving beef

production through feeding balanced diets and improved management practices, and

nature of available production systems. Producers were also required to allow the cattle

to meet a required final weight 400 kg (higher than normal harvest weights in Honduras)

and for them to be harvested at a central processing facility in Siguatepeque, Honduras.

Typically, cattle in Honduras are sold based on the economic need of the producer and

slaughtered before their weight potential is reached.

To evaluate beef production across Honduras, commonly practiced systems were

identified and enrolled in the study. These included cattle fed in total confinement,

combined intensive (confinement) and extensive (grazing), and extensive (grazing only).

For intensive production systems, locally available byproduct feedstuffs, including:

poultry litter, palm kernel meal, and freshly-chopped sugar cane were utilized to develop

individualized diets for each site. The poultry industry is prevalent across Honduras,

accordingly, poultry litter is a low-cost, readily available option for non-protein nitrogen.

Palm kernel meal is a byproduct from the palm oil industry and provides energy from

digestible fiber, and protein. The Honduran palm oil industry is large and the meal

currently inexpensive (approximately $174/DM tonne). In general, high-quality

feedstuffs for beef production are not available in Honduras, corn availability is limited

by region and season. Additionally, feeding is limited by processing capabilities, quality

plant-based protein sources must be imported. Diets were formulated based-on regional

feedstuff availability and cost of nutrients.

When outlining experimental procedures, management suggestions were made,

including protocols for vaccination, internal and external parasite control, implanting and

individual identification (ear tag). Producers at each location were advised to collect

individual animal weights at the beginning of the experiment, and at 28-d intervals, and

to record daily feed intakes (pen). Final body weights were collected at each site prior to

shipping, and 4% pencil shrink was applied. At specified end points (minimum of 400

kg), Texas Tech personnel collected carcass data and microbiology swabs at the

completion of each experiment. A local abattoir located near Siguatepeque, Comayagua

was utilized for all processing.

A second round of experiments were conducted during the summer of 2015.

Challenges that persisted during the first experiment were addressed through hands-on

producer training and modifications to protocols. Texas Tech personnel also visited the

farms more frequently for more direct experimental oversight. Trainings included

information on utilizing technologies best suited for respective production systems, diet

improvement through changes to grain processing, the importance of record keeping

systems, collection of diet samples for nutrient analysis, and demonstration of the

relationship between nutrient availability in feedstuffs and improved gain efficiencies.

All diets developed in the second stage of experiments (Table 1) targeted 13.5% crude

protein (DM basis). When possible, monensin was included in diets and more aggressive

implant strategies were utilized. Similar management and data collection practices were

advised as described previously.

Due to limitations of management and data collection, not all systems or

experiments resulted in usable data. The 5 experiments described below are a

combination of trials from the initial and second trials conducted in Honduras. The

experiments were selected based on reliability of data generated, eliminating sites that did

not record weights, samples, and or accidently changed diets during the evaluation

periods. Each of the 5 experiments was given a unique identification: Honduran

Management (HM) 1-5.

Central Region

HM1 & HM2 Experiments. The feedlot was located just outside of Siguatepeque,

Comayagua (Figure 4.1). All bulls (Brahman cross and crossbred) were purchased and

finished in confinement. The initial 2 experiments conducted started in October, 2014.

For HM1, 34 bulls (352 ± 22 kg) and HM2, 37 bulls (305 ± 13 kg) were fed for 108 and

165 d, respectively. Bulls were individually weighed 2 d prior to the experiment initiation

and sorted into respective weight groups. For HM1, cattle were weighed on d 19, 48, 76,

86, and 108, and HM2 were weighted on d 19, 48, 76, 105, 125, 153, and 165. Both lots

were implanted with Revalor G (Merck Animal Health, Austria), given Solution on d 3,

and administered Covexin on d 48. Cattle in HM1 were fed a palm kernel meal diet; bulls

were fed an adaptation ration (hay + starter concentrate) for 13 d; and starter concentrate

only for 5 d; followed by the finishing diet on d 19. Cattle in HM2 were fed a sugar cane

diet; bulls were initially fed an adaptation ration (hay + starter concentrate) for 4 d, a

starter ration (starter concentrate + sugar cane) for 14 d; and only then fed the finishing

diet on d 19. Both lots were fed twice daily (morning and afternoon) and bulls received

free choice mineral supplementation (Table 4.1). At the end of both experiments, bulls

were transported approximately 10 kilometers to the abattoir where trained Texas Tech

personnel collected carcass and microbiological data.

HM3 Experiment. Brahman cross and crossbred bulls (n = 38; initial BW

averaged 327 ± 75 kg) were purchased and received prior to the initiation of the

experiment which began July 23, 2015. Bulls were individually weighed prior to the start

of the experiment, and on d 0, 28, 56, 84, and 117 and fed for 118 d. Bulls received

Revalor L (Merck Animal Health, Austria) implant, albendazol (Zoetis Animal Health,

Colombia), goldmeck (ivermectin plus vitamins ADE), and covexin at the beginning of

the trial. Prior to the initiation the experiment, a receiving diet (concentrate + sugar cane)

was fed, cattle were transitioned to the distillers grain starter diet and fed for 11 d. At

experiment initiation, the distillers grain starter diet was fed for 3 d and then cattle were

transitioned to the finishing diet. The final diet was formulated for 13.5% crude protein

(DM basis) and included dried distillers grain and poultry litter as protein sources (Table

4.1). Cattle were fed twice daily (morning and afternoon) and bulls received free choice

mineral supplementation (Table 4.1). At the end of the experiment, bulls were transported

approximately 10 kilometers to the abattoir where trained Texas Tech personnel collected

carcass and microbiological data.

Southeast Region

HM4 Experiment. On September 2, 2015, a confined finishing experiment was

initiated on a ranch located approximately 50 kilometers outside of Danli, El Paraíso

(Figure 1). Bulls: 7 purebred Brahman, 18 Charolais x Brahman cross, 6 Brown Swiss x

Brahman cross, and 2 Angus x Brahman cross (n = 33; initial BW = 425 ± 51 kg) were

raised and finished on the ranch. Prior to experiment a sorting weight was taken and 33

bulls were selected based-on BW uniformity. Bulls were individually weighed on d 0, 14,

28, 41, 56, and 70 and fed for 74 d. The bulls were administered Vigantol, Blackleg,

Catosal (Bayer, Korea), Valbazen (Pfizer Animal Health, Brazil) and implanted with

Compudose 400 (Elanco Animal Health) prior to experiment initiation. Using feedstuffs

grown at the ranch and locally available, a diet was formulated for 13.5% CP (Table 4.1).

The starter diet was fed for 14 d and then cattle were transitioned to the finishing diet for

the remainder of the experiment. At the end of experiment, bulls were transported

approximately 270 kilometers to the abattoir where trained Texas Tech personnel

collected carcass and microbiological data.

Northwest Region

HM5 Experiment. On August 24, 2015, a confined finishing experiment was

initiated on a ranch located outside of San Pedro Sula, Cortés (Figure 4.1). Bulls (n = 57;

initial BW was 443 ± 20 kg) were purchased from Nicaragua and enrolled in the

experiment. Bulls were individually weighed on d 0, 28, 57, and 83 and fed for 84 d.

Before the initiation of the experiment, bulls were administered albendazol (Zoetis

Animal Health, Colombia), Boldenona (Colombia), Imizol (Merck Animal Health,

Germany), Vitamin ADE, and implanted with Revalor L (Merck Animal Health,

Austria). Bulls were fed the step 1 diet for 7 d, step 2 diet for 7 d, and the finishing for the

remainder of the experiment. Fresh cut grass was supplemented during step 1 and step 2

phases and slowly phased out in the finishing period. The finishing diet was formulated

for 13.5% CP utilizing soybean meal and poultry litter (Table 4.1). Animals were

provided free choice minerals and fed 3X daily (Table 4.1). At the end of the experiment,

bulls were shipped approximately 140 kilometers to the abattoir where trained Texas

Tech personnel collected carcass and microbiological data.

Statistical Analyses

Data for growth performance and carcass characteristics were analyzed using

PROC UNIVARIATE procedure of SAS (9.4 Inst. Inc., Cary, NC) for descriptive

analyses among diets. Additional measurement of data dispersion within diet was

provided only for reference.

RESULTS AND DISCUSSION

Dietary ingredients and calculated nutritional composition are reported in Table 4.1.

Feedstuffs utilized in diets differ across regions due to both availability and price

(transportation, importation, and cost). The central region lacks local feedstuffs and

therefore most are transported from other regions; however, producers are able access

most feedstuffs regardless of the location within the country. Poultry litter and sugar cane

are less available in the southeast region so neither feedstuff were included in the diet.

The HM4 producer grows corn and sorghum therefore those feedstuffs were utilized. The

HM5 producer is located close to San Pedro Sula and one of the main country ports;

therefore, transportation costs were lower. Additionally, HM5 grew sugar cane and had

poultry litter directly available to the ranch. Molasses was available at all locations and

was utilized in all diets. Local feed mills were utilized to mix concentrates when

available; if not available, the producer mixed the feed at the location. Milled

concentrates were mixed with roughage sources on location by the producer. The costs of

feedstuffs were factored into diet formulation and inclusion rates are reflective of price

and composition targets. Bos indicus influenced beef cattle were fed in three different

regions across Honduras (Figure 4.1). Initial BW ranged from 305 to 443 kg with an

average of 369 kg. Cattle fed in the central region were all placed on feed at lower body

weights. Nevertheless, cattle were fed varying days on feed to reach a similar final BW of

487 kg. Low final BW variability was obtained (CV = 7.9%). Cattle were fed for an

average of 110 d ranging from 74 to 165 d. Days on feed was basically defined by

average daily gain. When animals approached less efficient phase of growth, in which

more energy was deposited in the carcass, but less body weight (Owens et al. 1995),

producers were very reluctant on keep animals on feed. Average daily gain ranged from

0.84 to 1.31 kg with an average of 1.08 kg. Diets that contained greater inclusions of

ground corn (HM1, HM3, and HM5), pushed the ADG for grater gains. Corn has a

greater NEm and NEg than grain sorghum (NRC, 1996); the increased NEm and NEg of

corn was reflected in the increased energy content of HM1, HM3, and HM5. Corn is the

most common basal-grain source fed during finishing in the United States. Processed

corn (dry-rolled, high-moisture, or steam-flaked) corn is typically fed at inclusion rates

greater than 50% (DM basis) with the most common inclusion being 80 – 85% (DM

basis; Vasconcelos and Galyean, 2007). Corn was also the most common basal-grain

source fed in Honduras; however, due to processing differences and price restraints, corn

was fed at lower inclusion levels. Typically, only dry processing is applied (finely ground

or cracked). Finely ground corn should not be fed with low roughage levels as the risk of

acidosis is increased due to the rapid fermentation of the small particles (Owens, 2005).

By increasing the inclusion rate of corn, energy within the diet also increased. Corn has a

greater energy content than palm kernel meal (NRC, 1996). Nevertheless, it is still

considered a moderate source of energy and is fed at inclusion levels of 50 to 80% (DM

basis) with ADG of 1 to 1.2 kg/d were reported by Malaysia (Zahari and Alimon, 2003).

Even though palm kernel meal has a lower energy content, it is also a lower cost source

of energy; therefore, it was utilized in all of the diets. By feeding a lower cost, local

byproduct, the cattle had lower energy diets but were grown in a more sustainable

manner.

Dry matter intake ranged from 8.75 to 13 kg/d with an average intake of 10.81

kg/d, in which was very likely to be affected by a variety of factors. The increased DMI

intakes may be attributable to greater inclusion of roughages. Marques et al. (2016)

reported a linear increase in DMI as sugarcane bagasse increased. Benton et al. (2016)

reported no differences in DMI at standard U.S. roughage inclusion levels of alfalfa, corn

silage, or corn stalks; however, reported an increase in DMI between a low and a

standard inclusion of corn silage. Additionally, the authors note, a DM book value was

used for sorghum silage fed in HM4 so variation across DM may explain the increased

DMI. Genetic factors cannot be ignored. Bos indicus influenced cattle gain less

efficiently on high concentrate diets as they consume more and gain less than Bos taurus

cattle (Krehbiel et al., 2009). Although Bos indicus are less efficient, they are better

suited to handle heat and humidity stress and able to better utilize low quality forage and

grazing, making them better suited for Honduran environment conditions and growing

phases on grass (Beatty et al., 2006; Krehbiel et al., 2009). Gain efficiency ranged from

0.071 to 0.124 with an average of 0.101. One of the main factors driving low gain

efficiencies was the elevated intake of DM for some sites, more specifically the HM4.

The lower feed conversion may be caused by energy dilution (Galyean and Defoor,

2003). If the sorghum silage was of relatively poor quality the animals may have been

consuming more to maintain energy intake. Reduced energy could have also decreased

the protein utilization and resulted in the low efficiency. Furthermore, the low NEm and

NEg combined with the lower CP can help to explain the low efficiency of HM4.

Differences in G:F can additionally be attributed to protein utilization. Poultry litter is

high in protein; however, the fractions of protein greatly vary due to processing,

handling, poultry diets, and bedding source (Capucille et al. 2004). Capucille et al. 2004

reported recycled poultry bedding, poultry litter, to contain 43-45% non-protein nitrogen

and 55-58% true protein. The 2015 Feed Composition Table reported poultry manure,

dried contains 22% RUP (Beef Magazine). In contrast SBM is 34% RUP and DDGS are

52% RUP. These differences in protein fraction lead to the different utilization of protein.

The HM3 treatment had a more balanced RDP and RUP profile so the rumen microbes

and the animal were receiving protein allowing for more efficient conversion of feed.

Abattoir live weight was utilized for the calculation of dressing percentages as not

all animals had individual identification; therefore, TTU identification was used during

processing in the abattoir. Both abattoir live weight and adjusted abattoir live weight had

low variability (CV = 7.75). The range and mean were consistent as well. No other

adjusted performance data was calculated as individual live performance and carcass

quality were not matched through identification.

The HCW ranged from 250 to 301 kg with an average of 264 kg (CV = 8.0%).

Dressing percentage ranged from 54.03 to 58.01% with an average of 55.75%, with low a

low variability of (CV = 2.81%). The increased DP can be attributed to HM2 whose

dressing percentages ranged from approximately 55-61% (SEM = 2.31).

The LM area averaged 28.03 cm2 with low variability (CV = 6.12%). There was

increased variability of 12th-rib fat (CV = 19.4%) ranging from 3.82 to 6.54 mm with an

average of 5.15. On average 12th-rib fat was low across all treatments; interestingly, the

treatment with the lowest dietary EE had the greatest back fat. This may be attributed to

age and/or where the animals were on their growth curve. As cattle reach later maturity

they begin to deposit more subcutaneous fat and lean tissue accretion slows (Owens et al.,

1993).

The KPH ranged from 3.66 to 4.75% with an average of 4.14%. Marbling score

had low variability (CV = 7.45%) ranging from 254 to 313 with an average of 289. These

cattle were all of Brahman influence which partially attributed to their low marbling

scores (Damon et al., 1960; DeRouen et al., 1992; and Wheeler et al., 2001).

Feed cost of gain ranged from $0.40 to $0.67 with an average of $0.53 (SEM =

0.06). The FCOG is lower in the central region which can be attributed to feed costs,

DMI, and the total gain over the feeding period. Cattle on all three central treatments

consumed less but gained more over a longer feeding period, ultimately reducing the

IMPLICATIONS

All diets were viable options, for growth performance and carcass quality, for

beef producers within their respective regions. By locally sourcing both protein and

energy, poultry litter and palm kernel meal, respectively, this increases the sustainability

of the diet and beef cattle feeding. Palm kernel meal and corn blends were a viable option

for feedlot diets in Honduras. Animals fed an increased plane of nutrition reached a

targeted final BW. Variability of final BW was reduced by altering the days on feed. The

availability of byproducts and other feedstuffs at the central region of Honduras maybe

be the most important factor inducing better cost of gain compared to other regions.

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cereal and meat consumption. In: Proc. of the Nutri. Soc. 58:219-234.

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Zahari, M. W. and A. R. Alimon. 2003. Use of palm kernel cake and oil palm by-

products in compound feed. Palm Oil Developments. p. 5-9.

Figure 4.1. Honduran Producer Map

HM 4 HM 1-3

Table 4.1. Ingredient composition (DM basis) of the experimental diets fed in Honduras finishing trials

Treatment

Item HM11,3 HM21,3 HM31,3 HM44 HM51,5

Ingredient, %

Fresh Sugar Cane -- 37.30 20.00 -- 15.00

Palm Kernel Meal 30.90 20.40 15.00 17.00 20.00

Poultry Litter, dry 19.90 19.90 10.00 -- 8.00

Soybean Meal -- -- -- 8.12 5.00

Dried Corn Distillers Grain -- -- 15.00 -- --

Cracked Corn 40.80 15.80 30.00 -- 46.00

Ground Grain Sorghum -- -- -- 29.86 --

Ground Corn Cobs -- -- -- 20.00 --

Sorghum Silage -- -- -- 15.00 --

Molasses 8.40 6.5 10.00 8.00 5.00

Calcium Carbonate -- -- -- 1.00 1.00

Monensin 20 -- -- -- 0.02 --

Pecutrin Vitamindo -- -- -- 1.00 --

Calculated composition2, %

DM 86.72 42.93 55.90 72.62 65.20

CP 13.71 10.64 13.43 14.00 11.69

ADF 22.88 29.01 20.92 21.76 14.74

NDF 49.08 49.46 43.67 43.99 25.70

EE 5.50 4.49 5.97 4.57 3.54

Ca 0.72 0.61 0.51 0.83 0.65

P 0.47 0.43 0.43 0.44 0.33

NEm6 1.76 1.37 1.70 1.59 1.75

NEg6 1.13 0.79 1.08 0.98 1.13

1Cattle on these diets were given free choice mineral supplementation (Nutrivyn Crecimiento,

Argentina). Mineral contained: calcium (9-10.8%), phosphorous (5%), magnesium (1%), vitamin A

(200,000 IU), vitamin D3 (10,000 IU), vitamin E (80 IU), copper (750 mg), zinc (3,000 mg), manganese

(2,500 mg), iodine (60 mg), selenium (18 mg), cobalt (90 mg), chromium (40 mg), sodium (24%),

chlorine (36%), salt (55-66%). Recommended at 100 g per animal. 2Analyzed feedstuff compositions were used in calculation when samples from locations where

available, all other feedstuffs composition were taken from (NRC, 1996). 3Sample of palm kernel meal, poultry litter, and corn were taken from location. 4Sample of palm kernel meal, soybean meal, ground grain sorghum, and ground corn cobs were taken

from location. 5Sample of palm kernel meal and poultry litter were taken from location. 6All NEm and NEg feedstuff values were standard book values (NRC, 1996)

Table 4.2. Descriptive statistics for beef cattle finishing diets in Honduras

Item Mean1 S.E.M.1 SD1

Confidence

Interval1 CV, %1

Performance Characteristics

Initial BW, kg 369 26.58 59.42 305 - 443 16.10

Final BW, kg2 487 17.19 38.45 454 - 553 7.90

Days on feed 110 15.91 35.58 74 - 165 32.41

DMI, kg/d 10.81 0.76 1.70 8.75 - 13.00 15.73

ADG, kg 1.08 0.09 0.207 0.84 - 1.31 19.22

G:F, kg/kg 0.101 0.0093 0.0207 0.071 - 0.124 20.51

Carcass Characteristics

Abattoir live weight, kg 473 16.31 36.47 431 - 532 7.70

Adj. abattoir live weight 474 16.30 36.45 431 - 532 7.70

HCW, kg 264 9.44 21.11 250 - 301 8.00

Dressing percentage5 55.75 0.70 1.57 54.03 - 58.01 2.81

LM area, cm2 71.20 1.96 4.37 67.56 - 78.28 6.12

12th-rib fat, mm 5.15 0.45 1.00 3.82 - 6.54 19.40

KPH, % 4.14 0.21 0.46 3.66 - 4.75 11.11

Marbling score6 289 9.63 21.53 254 - 313 7.45

FCOG, $3,4 0.53 0.06 0.133 0.40 - 0.67 25.31 1Averages HM1-HM5 24% shrink was applied to final BW. 3FCOG = feed cost of gain 4Conversion of 22 lempiras to 1 U.S. dollar was used. 5HCW dived by abattoir live weight. 6200 = traces00, 300 = slight00.

Table 4.3. Descriptive growth performance, carcass, and cost statistics for individual finishing diets

Item HM1 HM2 HM3 HM4 HM5

Performance data

n 34 38 38 32 571

Initial BW

Mean, kg 352 305 327 419 443

Confidence Interval 322 - 413 274 - 329 197 - 456 352 - 483 368 - 516

CV, % 6.36 4.25 23.06 8.73 7.39

Final BW2

Mean, kg 470 454 475 481 553

CV, % 8.06 7.92 14.58 6.47 6.89

Mean, kg 8.75 9.66 10.75 13.00 11.91

Mean, kg 1.09 0.90 1.25 0.84 1.31

Confidence Interval 0.44 - 1.74 0.29 - 1.23 0.84 - 1.73 0.36 - 1.28 0.48 - 1.90

CV, % 24.33 21.12 16.59 25.42 22.27

Mean, kg/kg 0.124 0.093 0.116 0.071 0.101

CV, % 24.33 21.12 16.59 25.42 22.27

Mean, $4 0.46 0.40 0.43 0.67 0.67

CV, % 31.63 36.78 13.92 35.03 31.45

Carcass data

n 34 38 155; 386 155; 336 155; 526,

Abattoir live weight

Mean, kg 468 431 469 467 532

CV, % 8.44 7.90 16.67 6.24 4.36

Adj. abattoir live weight

Mean, kg 468 431 470 467 532

CV, % 8.97 8.29 19.10 7.66 4.95

Mean, kg 257 250 259 252 301

CV, % 8.97 8.29 19.10 7.66 4.95

Table 4.3. Continued.

Dressing percentage7

Mean, % 54.91 58.01 55.19 54.03 56.60

CV, % 3.02 2.46 4.76 3.60 4.32

LM area

Mean, cm2 67.56 78.28 70.69 70.28 71.76

CV, % 9.30 15.03 14.62 11.63 10.22

12th-rib fat

Mean, mm 4.71 5.45 5.21 3.82 6.54

CV, % 46.06 41.53 55.04 63.63 44.35

Mean, % 4.34 3.66 4.75 3.70 4.24

CV, % 12.26 10.79 14.73 28.32 10.34

Marbling score8

Mean 295 313 292 254 292

CV, % 22.40 15.42 30.62 24.58 22.13 1Final weight was not available for one animal; FBW, ADG, G:F, and FCOG were based on 56

animals 24% shrink was applied to final BW. 3FCOG = feed cost of gain 4Conversion of 22 lempiras to 1 U.S. dollar was used. 5Due to personnel and supplies limitations, sub-sample of 15 randomly selected carcasses were

assessed. 6Collected all LM area, 12th-rib fat, and marbling score data. Only 51 marbling scores collected for

HM5. 7HCW dived by abattoir live weight. 8100 = practically devoid00, 200 = traces00, 300 = slight00.

CHAPTER V

CONCLUSION

The role of byproducts in beef cattle production is essential for production and

economic sustainability. Distillers grain continues to play a significant role in livestock

production within the U.S. specifically in beef cattle. Developing countries such as

Honduras economically rely on the palm kernel industry; however, the true feeding

potential of the palm kernel meal byproduct has not been fully realized.

The source of distillers grain can have an impact on efficiency of the animal. The

physical differences of corn and grain sorghum results in distillers grain with inherent

feeding and digestibility differences. When fed at a moderate inclusion level, the G:F for

corn dried distillers grain treatment was greater than sorghum dried distillers grain

treatment. A tradeoff exists between corn and grain sorghum production as corn requires

more crop water but has a greater yield potential. The increased feed efficiency of corn

distillers grain and the increased yield potential of corn is realized in moderate to high

crop water use conditions as more beef can be produced with less crop water. However,

under low water input or dryland conditions, grain sorghum more efficiently used water

for beef production.

The use of palm kernel meal and other local feedstuffs is a viable option for

improving performance and carcass quality in Honduran beef cattle. Lower cost local

feedstuffs can be blended with more energy dense higher cost feedstuffs to increase the

energy of the diets and efficiency of the animal without exponentially increasing diet

costs. Feedstuff availability and cost varied by region directly impacting the diet

composition and the performance of the animal. Average daily gain was reflective these

diet differences, management strategies, and animal growth potential, these differences

were adjusted for by varying days on feed. By increasing the plane of nutrition and

varying days on feed, animals were able to reach greater final body weights than typically

seen in Honduras and reduce final body weight and carcass weight variability.

CHAPTER VI

APPENDICES

Table A-1. TAWC Grain Sorghum yield and total crop water 2005-2014

Year TCW1, mm Yield kg/ha

2005 196.9 5,733

2005 303.5 5,119

2006 216.9 3,318

2007 282.6 5,884

2007 380.4 7,997

2007 435.4 3,208

2007 440.3 8,634

2008 261.8 5,940

2008 280.4 4,203

2008 553.7 8,817

2008 663.7 9,191

2008 690.1 8,307

2009 358.9 8,460

2009 424.6 7,196

2009 523.1 7,151

2010 256.0 7,845

2010 306.8 6,359

2011* 740.6 1,341

2012 407.2 5,313

2012 748.0 8,940

2013 501.4 6,837

2013 687.1 9,881

2013 721.4 10,599

2014 368.3 8,552

2014 440.7 5,490

2014 473.7 7,670

2014 506.7 7,970

2014 529.6 7,846

2014 538.5 9,415

2014 734.1 6,214 1TCW= total crop water = total irrigation + effective rainfall + soil

moisture

*Sites that were not representative of harvested grain were removed from

the analysis.

Table A-2. TAWC Corn yield and total crop water 2005-2014

Year TCW1 (mm) Yield (kg/ha) Year TCW1 (mm) Yield (kg/ha)

2005 448.3 14,651 2012 403.9 9,277

2005 664.2 14,128 2012 431.8 6,364

2005 690.9 14,060 2012 530.9 7,030

2006 516.8 9,863 2012 602.0* 3,026

2006 521.5 7,877 2012 604.5 8,976

2006 578.9 11,417 2012 777.2 11,542

2006 699.8 11,800 2012 974.1 10,984

2007 476.3 10,891 2012 989.3 12,993

2007 497.6 14,302 2013 483.1 7,061

2007 523.5 14,418 2013 656.1 13,746

2007 557.3 15,311 2013 683.3 15,001

2008 514.1 13,226 2013 692.4 15,029

2008 605.8 9,116 2013 710.4 14,123

2008 668.0 15,813 2013 858.5 11,110

2008 710.9 12,365 2013 874.5 13,432

2008 818.9 12,679 2013 878.8 16,179

2008 873.6 14,625 2013 965.2 15,190

2008 899.5 15,580 2014 445.8 13,614

2008 1133.9 7,622 2014 447.0 10,827

2009 525.1 14,625 2014 569.0 13,495

2009 653.8 12,867 2014 570.2 13,181

2009 701.4 14,026 2014 576.3 10,827

2009 785.5 16,100 2014 607.1 12,240

2010 285.8 5,823 2014 637.5 13,558

2010 384.8 13,436 2014 645.2 9,917

2010 438.2 13,144 2014 768.4 17,324

2010 462.3 13,307

2010 502.9 14,437

2010 546.1 14,499

2010 604.3 10,400

2010 654.1 14,048

2010 660.4 14,235

2011* 365.0 0

2011* 348.3 0

2011* 373.0 0

2011* 573.3 3,452

2011* 681.4 2,641

2011 792.5 10,806

2011 979.7 11,989 1TCW= total crop water = total irrigation + effective rainfall + soil moisture

*Sites that were not representative of harvested grain were removed from the analysis.

ADDITIONAL HONDURAS TRIALS

Confined

On September 26, 2014, 27 Brangus bulls and 25 Brahman heifers were enrolled

in an experiment at the Continental Feedlot, located outside of San Pedro Sula. Both

groups of cattle were fed for 212 days in total confinement. Initial BW of the heifers was

281 ± 16 kg and final BW = 457 ± 29 kg (4% shrink applied to final weight). Bulls initial

BW was 247 ± 19 kg and finished at 420 ± 30 kg (4% shrink). At the initiation of the

experiment, both lots were implanted with Revalor-G (Merck Animal Health). A diet

consisting of corn silage, palm kernel meal, poultry litter, and molasses was formulated

for both groups of animals. The producer modified the diet by changing ingredient

percentages and removing poultry litter and replacing it with corn. This resulted in a

higher priced, protein deficient ration. Individual animal weights were taken on d 102,

172, and 212. Daily feed intake records were not available. At the end of the experiment,

cattle were shipped approximately 140 kilometers to Del Corral slaughter facility where

trained Texas Tech personnel collected carcass and microbiological data.

Grazing + Supplementation

Forty-seven Brahman, Brown Swiss, Holstein crossbred bulls, average initial BW

= 326 ± 34 kg were enrolled on study in a grazing + supplementation system located on

the Fondo Ganadero ranch near Juticalpa. Bulls were administered Ivermectin and

Vitamin ADE during the experiment. The bulls grazed pasture only from d 0 to 110. On d

111, the bulls began receiving concentrate, silage, and sugar cane supplementation. On d

168, silage and sugar cane were removed, and concentrate was supplemented for the

remainder of the experiment. Daily feed intake records were not available. Bulls were

individually weighed on days 0, 30, 62, 91, 122, 152, 182, and 205. Average final BW

was 437 ± 35 kg, with a 4% shrink applied. At the end of the experiment, bulls were

transported approximately 300 kilometers to the Del Corral slaughter facility where

Texas Tech personnel collected carcass and microbiological data.

Grazing

Twenty-four crossbred bulls were enrolled in the experiment the fall of 2014 on a ranch

near Juticalpa. Initial BW were not recorded by the producer. Individual BW were

recorded during the final 170 d of the experiment. Bulls were in a grazing only system

and received no supplementation throughout the experiment. Bulls were not implanted,

but were administered Ivermectin and Vitamin ADE during the experiment. Average

final BW = 417 ± 25 kg (4% shrink). At the end of the grazing period, bulls were

transported approximately 300 kilometers to the Del Corral slaughter facility where

Texas Tech personnel collected carcass and microbiological data.

Semi-Confined

On July 14, 2015, 2 feeding experiments to evaluate available protein sources (Lot 1 -

poultry litter diet and Lot 2 – wheat middling diet) were initiated at a ranch located

outside of Juticalpa. Twenty-five Brahman, Holstein, and Brown Swiss crossbred bulls

were fed in a semi-confined setting. A BW for sorting was obtained prior to initiation of

the experiment; bulls were selected based on uniformity of weight within each group.

Average initial BW = 370 ± 14 kg and 326 ± 9 kg for Lots 1 and 2, respectively; all bulls

were implanted with Revalor L on d 1. Bull were administered Ivermectin and Vitamin

ADE during the experiment. Respective diets evaluated poultry litter or wheat middlings

as a dietary protein source and were formulated for 13.5% CP (DM basis). Bulls were

transitioned to respective finishing diets over a 14 d period, gradually introducing

concentrate while decreasing roughage. Individual interim weights were taken on d 28,

56, 85, and 124. A 4% shrink was applied to final BW. Average final BW for Lot 1 = 470

± 24 kg and Lot 2 = 433 ± 22 kg. Data was inconsistently collected at the farm and the

protocols were altered; therefore, the performance data was deemed unusable. At the end

of the 124 d feeding period, bulls were transported approximately 300 kilometers to the

Del Corral slaughter facility where Texas Tech personnel collected carcass and

microbiological data.

copyright 2016, tosha l. opheim

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