Life Sciences Commons^™

Rumen Bacterial Community Structure Impacts Feed Efficiency In Beef Cattle, Henry A. Paz, Kristin E. Hales, James E. Wells, Larry A. Kuehn, Harvey C. Freetly, Elaine D. Berry, Michael D. Flythe, Matthew L. Spangler, Samodha C. Fernando

Department of Animal Science: Faculty Publications

The importance of the rumen microbiota on nutrient cycling to the animal is well recognized; however, our understanding of the influence of the rumen microbiome composition on feed efficiency is limited. The rumen microbiomes of two large animal cohorts (125 heifers and 122 steers) were characterized to identify specific bacterial members (operational taxonomic units [OTUs]) associated with feed efficiency traits (ADFI, ADG, and G:F) in beef cattle. The heifer and steer cohorts were fed a forage-based diet and a concentrate-based diet, respectively. A rumen sample was obtained from each animal via esophageal tubing and bacterial community composition was …

Risks Associated To Different Methods Of Increasing Pregnancy Rate Of Cows In Cow-Calf Systems, Tamara Esteves De Oliveira, Julio Otavio Jardim Barcellos, Jack Whittier, Odilene De Souza Teixeira, David Santos De Freitas, Ricardo Pedroso Oaigen, Matheus Dhein Dill, Concepta Mcmanus

Department of Animal Science: Faculty Publications

This study assessed the risks of different management practices to increase pregnancy rate in beef cow-calf systems, aiming at assisting decision-making. The perception of 18 experts on animal sciences regarding the risks of 32 nutritional, breeding, and general management practices applied to increase pregnancy rate were evaluated through questionnaires. The experts were selected by a non-probability sampling of researchers on veterinary and animal sciences. In addition, five farmers and eight technical consultants were also selected. The questionnaire was applied during a face-to-face meeting. The risk of each practice was assessed according to four factors, namely, cost, technical knowledge, operational complexity, …

Effects Of Syngenta Enogen Feed Corn Containing An Α-Amylase Trait On Finishing Cattle Performance And Carcass Characteristics, M. L. Jolly-Breithaupt, M. E. Harris, B. L. Nuttelman, D. B. Burken, J. C. Macdonald, M. K. Leubbe, T. K. Iragavarapu, G. E. Erickson

Department of Animal Science: Faculty Publications

Two experiments evaluated the effects of feeding a new corn hybrid, containing an α-amylase enzyme trait, Syngenta Enogen Feed Corn (SYT-EFC), on feedlot performance and carcass characteristics at two locations. Experiment 1 utilized 300 calffed steers (298.5 ± 16.3 kg of BW) at the University of Nebraska–Lincoln Eastern Nebraska Research and Extension Center Mead, NE. Treatments were designed as a 2 × 2 + 1– factorial arrangement with factors consisting of 1) corn type (SYT-EFC or conventional [CON]) and 2) byproduct type (with or without Sweet Bran [SB]), or a BLEND of STY-EFC and CON without SB. In Exp. 2, …

Economic Selection Index Development For Beefmaster Cattle I: Terminal Breeding Objective, Kathleen P. Ochsner, M. D. Macneil, Matthew L. Spangler

Department of Animal Science: Faculty Publications

The objective of this study was to develop an economic selection index for Beefmaster cattle in a terminal production system where bulls are mated to mature cows with all resulting progeny harvested. National average prices from 2010 to 2014 were used to establish income and expenses for the system. Phenotypic and genetic parameter values among the selection criteria and goal traits were obtained from literature. Economic values were estimated by simulating 100,000 animals and approximating the partial derivatives of the profit function by perturbing traits one at a time, by 1 unit, while holding the other traits constant at their …

Economic Selection Index Development For Beefmaster Cattle Ii: General-Purpose Breeding Objective, Kathleen P. Ochsner, M. D. Macneil, Ronald M. Lewis, Matthew L. Spangler

Department of Animal Science: Faculty Publications

An economic selection index was developed for Beefmaster cattle in a general-purpose production system in which bulls are mated to a combination of heifers and mature cows, with resulting progeny retained as replacements or sold at weaning. National average prices from 2010 to 2014 were used to establish income and expenses for the system. Genetic parameters were obtained from the literature. Economic values were estimated by simulating 100,000 animals and approximating the partial derivatives of the profit function by perturbing traits 1 at a time, by 1 unit, while holding the other traits constant at their respective means. Relative economic …

The Impact Of Training Strategies On The Accuracy Of Genomic Predictors In United States Red Angus Cattle, J. Lee, Stephen D. Kachman, Matthew L. Spangler

Department of Animal Science: Faculty Publications

Genomic selection (GS) has become an integral part of genetic evaluation methodology and has been applied to all major livestock species, including beef and dairy cattle, pigs, and chickens. Significant contributions in increased accuracy of selection decisions have been clearly illustrated in dairy cattle after practical application of GS. In the majority of U.S. beef cattle breeds, similar efforts have also been made to increase the accuracy of genetic merit estimates through the inclusion of genomic information into routine genetic evaluations using a variety of methods. However, prediction accuracies can vary relative to panel density, the number of folds used …

Development Of Terminal And Maternal Economic Selection Indices In Beefmaster Cattle, Kathleen P. Ochsner

Department of Animal Science: Dissertations, Theses, and Student Research

In the design of economic selection indices, the relative importance of traits in the breeding objective is reflected by their relative economic weighting. The objective of this study was to develop two economic selection indices for Beefmaster cattle: one for a terminal production system and one for a maternal production system. The terminal index was developed assuming bulls are mated to mature cows with all resulting progeny harvested. The maternal index was developed assuming bulls are mated to a combination of heifers and mature cows, with resulting progeny retained as replacements or sold at weaning.

National average prices from 2010 …

Genetic Parameters For Docility, Weaning Weight, Yearling Weight And Intramuscular Fat Percentage In Hereford Cattle, Jose A. Torres-Vazquez

Department of Animal Science: Dissertations, Theses, and Student Research

Temperament in cattle can be described as the reactivity or fear response to human handling, and it is important to beef cattle producers not only from a human safety but also due to potential correlations with other economically traits. Before a docility selection metric can be added to a genetic evaluation, any potential antagonisms with economically relevant traits should be quantified. The objective was to estimate genetic parameters, including genetic correlations, for chute score (CS), weaning weight (WW), yearling weight (YW), and intramuscular fat percentage (IMF) in Hereford cattle. Single-trait and bivariate animal models were used to estimate heritabilities and …

Effects Of Sorghum Wet Distillers Grains Plus Solubles In Steam-Flaked Corn–Based Finishing Diets On Steer Performance, Carcass Characteristics, And Digestibility Characteristics, E. K. Buttrey, K. H. Noel, F. T. Mccollum Iii, N. A. Cole, L. O. Tedeschi, James C. Macdonald

Department of Animal Science: Faculty Publications

Two studies were conducted to evaluate the effects of sorghum wet distillers grains (SWDGS) in finishing diets on steer performance, carcass characteristics, and nutrient digestibility. In Exp. 1, 240 steers (initial BW = 379 ± 1 kg) were fed steam-flaked corn–based diets with or without 25% SWDGS and 7.5, 10.0, or 12.5% alfalfa hay. There were no effects of alfalfa hay concentration on BW, DMI, ADG, or G:F (P ≥ 0.16). Including SWDGS reduced (P ≤ 0.05) ADG and G:F. Fat thickness decreased (P = 0.03) and DP tended to decrease (P = 0.09) linearly as level of alfalfa hay …

Effects Of Fat And/Or Methionine Hydroxy Analog Added To A Molasses-Urea-Based Supplement On Ruminal And Postruminal Digestion And Duodenal Flow Of Nutrients In Beef Steers Consuming Low-Quality Lovegrass Hay, R. Lopez, G. D. Bernhard, J. E. Guerra-Liera, S. A. Soto-Navarro, L. A. Balstad, M. K. Petersen, D. V. Dhuyvetter, M. S. Brown, C. R. Krehbiel

Department of Animal Science: Faculty Publications

Five crossbred beef steers (initial BW = 338.6 ± 7.8 kg) fitted with ruminal and duodenal cannulas were used in a 5 × 5 Latin square design experiment to evaluate the effects of methionine hydroxy analog (MHA) and/or yellow grease (fat) added to a molassesurea- based supplement on intake and characteristics of digestion. Steers were fed low-quality hay (long-stem lovegrass Eragrostis curvula: 3.3% CP, 76.8% NDF; DM basis) ad libitum and supplemented with 0.91 kg/d (as fed) of 1 of 4 supplements in a 2 × 2 + 1 factorial arrangement of treatments. Supplemental treatments were 1) control (no supplement, …

Feeding Wet Distillers Grains Plus Solubles With And Without A Direct-Fed Microbial To Determine Performance, Carcass Characteristics, And Fecal Shedding Of Escherichia Coli O157:H7 In Feedlot Heifers, B. K. Wilson, B. P. Pulsipher, D. L. Step, M. E. Jacob, D. L. Vanoverbeke, C. J. Richards, T. G. Nagaraja, C. R. Krehbiel

Department of Animal Science: Faculty Publications

The inclusion of wet distillers grains plus solubles (WDGS) in feedlot diets has become a common practice in many regions of the United States due to the expanded production of byproducts and fluctuating corn prices related to ethanol production and other factors. In addition, societal concerns over the continued use of antimicrobials in agriculture production combined with an enhanced interest in disease and pathogen prevention in the food supply have led to an increased interest in use of direct-fed microbials (DFM) in growing and finishing cattle. Direct-fed microbials have been shown to improve ADG and feed efficiency, alter ruminal fermentation, …

Genetic Parameters For Docility, Weaning Weight, Yearling Weight, And Intramuscular Fat Percentage In Hereford Cattle, J. A. Torres-Vázquez, Matthew L. Spangler

Department of Animal Science: Faculty Publications

Cattle behavior, including measures of docility, is important to beef cattle producers not only from a human safety perspective but also due to potential correlations to economically relevant traits. Field data from the American Hereford Association was used to estimate genetic parameters for chute score (CS; n = 25,037), weaning weight (WW; n = 24,908), yearling weight (YW; n = 23,978), and intramuscular fat percentage (IMF; n = 12,566). Single-trait and bivariate animal models were used to estimate heritabilities and genetic correlations. All models included fixed effects of sex and contemporary group, defined as herd–year–season, and direct genetic and residual …

Corn Residue Stocking Rate Affects Cattle Performance But Not Subsequent Grain Yield, L. A. Stalker, H. Blanco-Canqui, Jennifer A. Gigax, A. L. Mcgee, T. M. Shaver, S. J. Van Donk

West Central Research and Extension Center, North Platte

This study investigated effects of stocking rate on cattle performance, quality and quantity of corn residue, and impact of residue removal on grain yield for 5 yr at the University of Nebraska – Lincoln West Central Water Resources Field Laboratory near Brule, NE. Four removal treatments—1) no removal (control), 2) grazing at 2.5 animal unit month (AUM)/ ha, 3) grazing at 5.0 AUM/ha, and 4) baling—were applied to a center pivot–irrigated corn field (53 ha). The field was divided into eight 6.6-ha paddocks to which replicated treatments were assigned. Samples of residue were collected in October and March (before and …

The Effects Of Technology Use In Feedlot Production Systems On Feedlot Performance And Carcass Characteristics, C. L. Maxwell, B. C. Wilson, C. F. O'Neill, B. K. Wilson, C. G. Hixon, C. L. Haviland, A. N. Grimes, M. S. Calvo-Lorenzo, D. L. Vanoverbeke, G. G. Mafi, C. J. Richards, D. L. Step, B. P. Holland, C. R. Krehbiel

Department of Animal Science: Faculty Publications

The objectives of this study were to examine the effects of feedlot production systems with and without the use of a β-adrenergic agonist compared to an all-natural production program on feedlot performance and carcass characteristics. Crossbred beef steers (n = 336; initial BW = 379 ± 8 kg) were randomized to 1 of 3 treatments in a randomized complete block design (RCBD; 14 steers/pen; 8 pens/treatment). Treatments consisted of an all-natural treatment (NAT), a conventional treatment (CONV), and a conventional treatment with a β-agonist (CONV-Z). All treatments were fed the same basal diet with NAT cattle receiving no growth promoting …

Seasonal Variation In Vitamin D Status Of Beef Cattle Reared In The Central United States, E Casas, J D. Lippolis, L A. Kuehn, T A. Reinhardt

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The objective was to retrospectively measure seasonal sunlight-associated variation in serum concentrations of 25-hydroxyvitamin D (25OHD) in beef cattle. The concentration of 25OHD was measured in crossbred animals born from March to May in 2011 and 2012. Vitamin D status 2 to 3 mo after birth (period 1) was only available for 2012 calves and was measured in June 2012. Period 1 animals had serum 25OHD concentrations of 26.3 +- 1.5 ng/mL. The 25OHD concentrations for late summer (period 2) were 46.6 +- 1.4 and 51.0 +- 1.5 ng/mL for 2011 and 2012, respectively. Serum concentration of 25OHD in early …

Feeding Condensed Distillers Solubles To Feedlot Finishing Steers And The Effects Of Feed Additives In Adaptation Diets, Marie E. Harris

Department of Animal Science: Dissertations, Theses, and Student Research

By-products from the dry-milling ethanol process can be used in cattle diets to replace corn. There is a significant interaction between corn processing methods as CCDS concentration increases in the diet. Improvements are observed for SFC in final BW, ADG, and G:F over DRC. An experiment was conducted to determine if greater concentrations of CCDS could be fed in SFC based diets and maintain or improve performance. Performance and carcass characteristics were evaluated with increasing concentrations of CCDS at 0, 9, 18, 27, or 36% in place of SFC in feedlot finishing diets. As CCDS concentration increased, DMI decreased quadratically. …

Uncertainties In Life Cycle Greenhouse Gas Emissions From U.S. Beef Cattle, Quentin M. Dudley, Adam Liska, Andrea K. Watson, Galen E. Erickson

Adam Liska Papers

Beef cattle feedlots are estimated to contribute 26% of U.S. agricultural greenhouse gas (GHG) emissions, and future climate change policy could target reducing these emissions. Life cycle assessment (LCA) of GHG emissions from U.S. grain-fed beef cattle was conducted based on industry statistics and previous studies to identify the main sources of uncertainty in these estimations. Uncertainty associated with GHG emissions from indirect land use change, pasture soil emissions (e.g. soil carbon sequestration), enteric fermentation from cattle on pasture, and methane emissions from feedlot manure, respectively, contributed the most variability to life cycle GHG emissions from beef production. Feeding of …

Qtls Associated With Dry Matter Intake, Metabolic Mid-Test Weight, Growth And Feed Efficiency Have Little Overlap Across 4 Beef Cattle Studies, Mahdi Saatchi, Jonathan E. Beever, Jared E. Decker, Dan B. Faulkner, Harvey C. Freetly, Stephanie L. Hansen, Helen Yampara-Iquise, Kristen A. Johnson, Stephen D. Kachman, Monty S. Kerley, Jaewoo Kim, Daniel D. Loy, Elisa Marques, Holly L. Neibergs, E. John Pollak, Robert D. Schnabel, Christopher M. Seabury, Daniel W. Shike, W. M. Snelling, Matthew L. Spangler, Robert L. Weaber, D. J. Garrick, Jeremy F. Taylor

Department of Animal Science: Faculty Publications

Background: The identification of genetic markers associated with complex traits that are expensive to record such as feed intake or feed efficiency would allow these traits to be included in selection programs. To identify large-effect QTL, we performed a series of genome-wide association studies and functional analyses using 50 K and 770 K SNP genotypes scored in 5,133 animals from 4 independent beef cattle populations (Cycle VII, Angus, Hereford and Simmental × Angus) with phenotypes for average daily gain, dry matter intake, metabolic mid-test body weight and residual feed intake.

Results: A total of 5, 6, 11 and 10 significant …

Effects Of Beef Production System On Animal Performance And Carcass Characteristics, C. L. Maxwell, C. R. Lopez, B. K. Wilson, B. T. Johnson, B. C. Bernhard, C. F. O'Neill, D. L. Vanoverbeke, G. G. Mafi, D. L. Step, C. J. Richards

Department of Animal Science: Faculty Publications

The objective of this study was to evaluate conventional (CONV) and natural (NAT) beef production systems from annual pasture through finishing through grazing. Beef steers (n = 180, initial BW = 250 ± 19 kg) were assigned randomly to 2 treatments in the pasture phase. Steers were implanted with 40 mg of trenbolone acetate (TBA), 8 mg estradiol, and 29 mg tylosin tartrate (CONV), or received no implant (NAT). Steers on the 2 treatments grazed wheat or cereal rye for 109 d. Conventional steers had an 18.5% improvement in ADG (1.22 vs. 1.03 kg/d, P < 0.01) and a heavier final BW (385 vs. 366 kg, P < 0.01) compared with NAT steers. Following the pasture phase, steers (n = 160 steers, 5 steers/pen, 8 pens/treatment) were assigned to a 2 × 2 factorial in the feedlot phase. Production system (NAT vs. CONV) was maintained from the pasture phase, and the second factor was 7 vs. 12% low-quality roughage (DM basis, LOW vs. HIGH). During finishing, CONV steers were given 120 mg of TBA and 24 mg estradiol at processing, fed monensin and tylosin, and fed zilpaterol hydrochloride for the last 20 d of the experiment. There were no program × roughage level interactions (P > 0.07). The CONV steers ate …

Beef Cattle Body Temperature During Climatic Stress: A Genome-Wide Association Study, Jeremy T. Howard, Stephen D. Kachman, Warren M. Snelling, E. John Pollak, Daniel C. Ciobanu, Larry A. Kuehn, Matthew L. Spangler

Department of Animal Science: Faculty Publications

Cattle are reared in diverse environments and collecting phenotypic body temperature (BT) measurements to characterize BT variation across diverse environments is difficult and expensive. To better understand the genetic basis of BT regulation, a genome-wide association study was conducted utilizing crossbred steers and heifers totaling 239 animals of unknown pedigree and breed fraction. During predicted extreme heat and cold stress events, hourly tympanic and vaginal BT devices were placed in steers and heifers, respect i v e l y. I n d i v i dua l s we r e genotyped with t h e BovineSNP50K_v2 assay and data …

Supplementing Distillers Grains In A Yearling System As A Forage Replacement Tool With Bunk Or Ground Feeding, And Impact Of Winter Supplementation Level On Finishing Performance And Profit, Kari L. Gillespie

Department of Animal Science: Dissertations, Theses, and Student Research

The benefit of adding weight to cattle prior to entering the finishing phase through a forage-based backgrounding system has become more important with increased corn price. Further, as competition for available forage increases, the value of replacing grazed forage with a supplement such as distillers grains, also increases.

A 2-year beef systems study evaluated optimal supplementation time of distillers grains and summer forage savings with distillers supplementation. High winter level supplementation of distillers grains increased winter ADG, decreased summer ADG, and increased final live weights and HCW compared to cattle supplemented at a low supplement level designed to only meet …

Late Gestation Supplementation Of Beef Cows Differing In Body Condition Score: Effects On Cow And Calf Performance, D. W. Bohnert, L. A. Stalker, R. R. Mills, A. Nyman, S. J. Falck, R. F. Cooke

West Central Research and Extension Center, North Platte

A 2-yr study utilizing 120 mature, crossbred (Angus × Herford) cows/year, evaluated the influence of cow BCS and dried distillers grains with solubles (DDGS) supplementation during late gestation on cow performance and productivity of subsequent offspring. Treatments were arranged as a 2 × 2 factorial in a randomized complete block design with 2 BCS and with or without DDGS supplementation. Cows were nutritionally managed to enter the last trimester of gestation with a BCS of approximately 4 (LBCS) or 6 (HBCS) and were thereafter managed in a single herd (initial BCS were 4.4 and 5.7 for LBCS and HBCS treatments, …

Review: Life-Cycle, Total-Industry Genetic Improvement Of Feed Efficiency In Beef Cattle: Blueprint For The Beef Improvement Federation, Merlyn K. Nielsen, M. D. Macneil, J. C. M. Dekkers, D. H. Crews Jr., T. A. Rathje, R. Mark Enns, R. L. Weaber

Department of Animal Science: Faculty Publications

On a life-cycle basis, beef animals are able to consume large amounts of low-cost, low-quality forages relative to higher-cost concentrates compared with pigs and chickens. However, of the 3, beef is still more expensive to produce on a cost–per–edible pound basis. Accordingly, there is need for genetic programs and management changes that will improve efficiency, sustainability, and profitability of beef production. Options include improving reproductive rate, reducing feed used for maintenance, or both, while not reducing output. A goal for improving efficiency of feed utilization is to reduce the amount or proportion of feed used for maintenance. Such reduction is …

The Effect Of Myostatin Genotype On Body Temperature During Extreme Temperature Events, J. T. Howard, Stephen D. Kachman, Merlyn K. Nielsen, Terry L. Mader, Matthew L. Spangler

Department of Animal Science: Faculty Publications

Extreme heat and cold events can create deleterious physiological changes in cattle as they attempt to cope. The genetic background of animals can influence their response to these events. The objective of the current study was to determine the impact of myostatin genotype (MG) on body temperature during periods of heat and cold stress. Two groups of crossbred steers and heifers of unknown pedigree and breed fraction with varying percentages of Angus, Simmental, and Piedmontese were placed in a feedlot over 2 summers and 2 winters. Before arrival, animals were genotyped for the Piedmontese-derived myostatin mutation (C313Y) to determine their …

The Impact Of Genetic Background On Body Temperature Regulation In Beef Cattle During Periods Of Heat And Cold Stress., Jeremy T. Howard

Department of Animal Science: Dissertations, Theses, and Student Research

Cattle are reared in environments that differ and vary greatly in climate, thus the ability to regulate body temperature across multiple environments is essential. However, inherent differences between animals do exist and can influence their response to extreme temperatures. The objectives of the current study were to model the impact of myostatin genotype (MG) on body temperature during heat and cold stress and conduct a genome-wide association study (GWAS) to better understand the genetic basis of body temperature regulation during extreme temperatures.

Crossbred steers and heifers (n= 239) with varying degrees of Piedmontese influence were fed in four groups over …

Utilization Of Corn Condensed Distillers Solubles And Forages In Management Systems For The Cow-Calf Enterprise, Jason M. Warner

Department of Animal Science: Dissertations, Theses, and Student Research

Of the annual expenses necessary to maintain a beef cow, feed and forage are the greatest and most variable. Thus, nutrition programs for cow-calf operations must be developed using economical feedstuffs that optimize cowherd performance. The corn dry-milling industry provides several feedstuffs that are often the most economical sources of energy and protein, but considerations for storage and handling are necessary. Two experiments evaluated an alternative form of storing corn condensed distillers solubles (CCDS) by applying to grass hay windrows before baling. Round bales were treated with either 0 or 20% (Exp. 1); or 0, 16, and 32% (Exp. 2) …

Use Of A Complete-Feed Diet (Ramp) To Rapidly Transition Cattle To A Finishing Diet, C. J. Schneider, Brandon L. Nuttelman, Dirk Burken, Terry J. Klopfenstein, Galen E. Erickson

Department of Animal Science: Faculty Publications

A study evaluated transitioning cattle from RAMP to a finishing diet with fewer intermediate step diets and days fed during transition. Yearling crossbred steers (n = 390; BW = 341 ± 14 kg) were blocked and stratified by BW, and assigned randomly within strata to 40 feedlot pens, with 9 or 10 steers per pen. Treatments were different grain adaptation programs (27 or 28 d) involving blends of RAMP and finishing diet. A control adaptation program involved decreasing RAMP and increasing a 62.5% corn finishing diet (62.5% high moisture corn (HMC), 25% sweet bran, 7.5% alfalfa hay (AH), and 5% …

Use Of A Complete-Feed Diet (Ramp) In Grain Adaptation Programs Compared To Traditional Grain Adaptation Programs, C. J. Schneider, Brandon L. Nuttelman, Kelsey M. Rolfe Rolfe, William A. Griffin, Terry J. Klopfenstein, Galen E. Erickson

Department of Animal Science: Faculty Publications

A study evaluated using RAMP to adapt cattle to a high grain finishing diet. Yearling crossbred steers (n = 229; BW = 397 ± 28.4 kg) were consecutively weighed over 2 d, stratified by BW, and assigned randomly within strata to 18 feedlot pens, with 12 or 13 steers per pen. Treatments were imposed during grain adaptation (22 d) by decreasing RAMP (100 to 0%) and increasing finishing diet (0 to 100%). RAMP was fed either as a blend in a 1-diet system which was delivered twice daily (RAMP-1RS) or as 2 daily diets where RAMP was delivered in one …

Occurrence Of Hormonal Residues In Feedlot Cattle Waste, Terry L. Mader, Leslie J. Johnson, Shannon L. Bartelt-Hunt, Daniel D. Snow, William Kranz, Charles Shapiro, Simon Van Donk, David P. Shelton, David Tarkalson, T. C. Zhang, Steve Ensley

Department of Animal Science: Faculty Publications

Two identically designed studies were conducted in separate years at the UNL Haskell Agricultural Laboratory using 192 crossbred heifers (96/study). Within a study heifers (initial weight = 386kg) were randomly assigned to 2 groups (3 42.4 m × 14.6 m pens/group/year): 1) treatment (TRT) animals were administered synthetic hormones via subcutaneous implants [d 1, 36 mg zearalonal; d 35, 140 mg trenbolone acetate (TBA) and 14 mg of 17β-estradiol benzoate (Revalor-H)] and fed Melengesterol Acetate (MGA), and 2) control (CON) animals with no synthetic hormone provided. Throughout each study, feedlot pen surface samples were obtained from 4 equally-sized zones (5 …

Opportunities And Challenges From The Use Of Genomic Selection For Beef Cattle Breeding In Latin America, Hugo H. Montaldo, Eduardo Casas, José Bento Sterman Ferraz, Vicente E. Vega-Murillo, Sergio Iván Román-Ponce

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In 2009, Latin American countries had approximately 401 million cattle (29% of the world’s total cattle population) and produced 8.2 million tonnes of beef, equivalent to 29% of the world’s total production (FAO, 2011). Beef in Latin American countries is produced under widely differing climates (ranging from tropical to temperate), resources available (vegetation, food), types of markets, and genetic backgrounds of the animals. The main production systems are classified as beef and dual-purpose cattle. The genetic backgrounds of animals vary from purebred European (Bos taurus taurus) or Zebu (Bos taurus indicus) to crossbreeds (Figures 1 and …