Animal Sciences Commons^™

The Impact Of Oxidative Stress On Postmortem Meat Quality, Nicolas J. Herrera

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

Tenderness is the primary factor to influence consumer palatability in fresh meat. The tenderization of muscle is dependent on proteolytic mechanisms, including calcium dependent, non-lysosomal endogenous enzymes such as calpains and proteasomes. These mechanisms have been indicated alongside apoptosis early postmortem as cascades of apoptotic events promote ideal conditions for postmortem tenderization. Recent literature has identified oxidative stress-mediated events to be linked to apoptotic activity. Oxidative stress is defined as the overwhelming production of reactive species compared to homeostatic, endogenous antioxidants present within muscle systems. These conditions exhaust antioxidant function and facilitate reactive species to alter protein, lipid, or nucleic …

Evaluation Of Growth Promoting Implant Strategies And Days On Feed On Finishing Heifer Performance And Evaluation Of Optimal Reimplant Times For Finishing Heifers And Steers, Caitlin Ohnoutka

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

Two experiments evaluated the effects of delayed, long-acting coated implants or uncoated implants to non-implanted heifers fed for constant or varying days on feed. In Exp. 1, heifers were implanted with either Revalor-XH on d 1, Revalor-200 on d 1, Revalor-XR on d 1, or Revalor-200 on d 70 compared to non-implanted control heifers when fed for an average of 198 d. In Exp. 2, heifers were implanted with Revalor-200 on d 1 and reimplanted with Revalor-200 on d 100, Revalor-XH on d 1, or not implanted and fed for different days on feed: 151, 165, 179, or 193. Implanting …

Identifying Breed Effects For Cow Mature Weight, Madeline J. Zimmermann

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

Mature weight (MWT) in beef cattle has increased over the past 30 yr. In general, larger cows are costlier to maintain than smaller cows, and their profitability depends on their production environment. A wide range of beef production environments exist in the United States. There are also a variety of beef cattle breeds that can be chosen and mated to create a type of cow which will be optimally suited to excel in a given environment. However, there remains a need for tools allowing effective comparison among breeds to facilitate such decision making. Unfortunately, estimated progeny differences ( …

Evaluation Of Alpha Amylase Containing Corn On Finishing Cattle Performance And Digestibilty, Melissa L. Jolly-Breithaupt

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

One digestion and four finishing trials were conducted to evaluate the effect of a new corn hybrid containing an α-amylase trait, Syngenta Enogen Feed Corn (SYT-EFC) on site and extent of digestion, ruminal fermentation parameters, and feedlot performance. Experiments utilized corn containing the enzymatic gene compared to controls, the near isoline parental corn (NEG) or commercially available corn grain (CON), processed as dry-rolled corn (DRC) or high moisture corn (HMC) in diets with dry [distillers grains plus solubles (DGS)] or wet (Sweet Bran) milling byproducts. The corn grain of the experimental diets were fed as the sole grain source, comprising …

The Effects Of Feed Additives In Beef Finishing Systems And The Effect Of Rumen Degradable Protein Supplementation In Corn Residue Grazing Systems With The Use Of Distillers On Growth Performance, Robert M. Jones

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

One receiving trial evaluated the effect of the feed additive monensin (trade name: Rumensin) on steer growth performance in the receiving period while evaluating the effects of two receiving vaccinations on morbidity and mortality of newly received calves. No differences were observed in growth performance, morbidity rate or mortality rate between treatments for the first 28 d of receiving. A finishing trial evaluated the effect of the feed additive ractopamine hydrochloride (trade name: Optaflexx) on feedlot growth performance and carcass characteristics of crossbred yearling steers fed to differing degrees of finish. Feeding ractopamine hydrochloride at 300 mg improved ADG, G:F, …

The Influence Of Diet And Oxidation On Calcium Retention Of The Mitochondria In Fresh Beef, Emery K. Wilkerson

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

Distillers grains (DG) contribute to cattle sarcoplasmic reticulum (SR) membrane instability by increasing poly-unsaturated fatty acid (PUFA) content in the SR membrane, possibly resulting in early postmortem calcium (Ca) leakage and improved tenderness. Mitochondria are relatively easy to isolate intact and provide the opportunity to study Ca in an SR model. The objective of this research was to determine the influence of diet and oxidation on Ca release from mitochondria. Cattle (n=48) were fed a corn-based finishing diet with or without deoiled, dried DG (50% DM basis). Steaks from each strip loin were aged for 2, 8, 14, and 21 …

Effects Of Feeding Field Peas On Fresh Beef Quality, Hope Voegele

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

The objective of this study was to evaluate the use of field peas during two phases of production (grazing and finishing) on fresh beef quality. A total of 232 crossbred steers and heifers were randomly assigned to one of six dietary treatments in a 3x2 factorial consisting of 3 pasture and 2 finishing supplementations. The pasture phase consisted of 1) no supplement, 2) field peas at 0.5% BW, or 3) dry-rolled corn supplement at 0.5% of BW. The finishing phase consisted of 1) field peas at 20% DM or 2) no field peas. During this two-year study, steers (year 1) …

Antimicrobial Interventions Applied To Beef Sub-Primals For The Control Of Escherichia Coli And Their Impact On Ground Beef Quality, Kelly Ann Mccarty

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

Due to their severe health implications, seven shiga toxin-producing E. coli (STEC) serotypes were declared adulterants by USDA-FSIS in raw, non-intact beef products. Small business beef processing facilities are being asked to implement an intervention on the beef sub-primals and trim they receive for ground beef production. This study evaluates the efficacy of reducing rifampicin-resistant E. coli (E. coli^Rif) using 4.5% lactic acid (LA), 2.5% Beefxide™ (BX), and 380 ppm peroxyacetic acid (PAA) when applied by dip, spray or electrostatic spray (ESS) to the mostly fat lateral surface and mostly lean medial surface of beef shoulder clods …

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 …

Effects Of Salt And Nitrite Concentration On The Shelf Life Of Deli-Style Ham, Regan E. Stanley

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

Deli-style hams were manufactured to measure the effects of salt and nitrite concentration on shelf life and physicochemical characteristics. Three replications of deli-style ham treatments were manufactured in a 3 x 4 factorial arrangement of salt concentration (0.7%, 1.4%, or 2.1%, meat block basis) and nitrite concentration and source (0 ppm, 100 ppm or 200 ppm sodium nitrite, SN, or 100 ppm sodium nitrite equivalent from pre-converted celery juice powder, CP; Veg Stable 506, Florida Food Products). Salt concentration, water activity, cook yield, and texture profile analysis (TPA) were measured on w 0. Color, pH, residual nitrite, and aerobic and …

Evaluation Of The Metabolic Response, Blood Chemistry Profile, And Cardiac Morphology Of Beef Heifers Supplemented With Zilpaterol Hydrochloride Followed By An Endocrine Induced Stress Challenge, Joe O. Buntyn

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

The objective of this study was to determine the metabolic, stress, hematology, organ weights, histology and cardiac anatomical features of beef heifers supplemented with zilpaterol hydrochloride (ZH) when exposed to a corticotropin-releasing hormone (CRH) and arginine vasopressin (VP) challenge. Crossbred heifers (n = 20; 556 ± 7 kg BW) were randomized into two treatment groups: 1) Control (CON): no ZH, and 2) Zilpaterol (ZIL): supplemented with ZH at 8.33 mg / kg (DM basis). The ZIL group was supplemented ZH for 20 d, with a 3-d withdrawal period. On d 24, heifers received an intravenous bolus of CRH (0.3 µg …

Impact Of Finishing Diets With De-Oiled Distillers Grains Or Antioxidant Containing Supplement On Beef Shelf Life, Katherine I. Domenech-Perez

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

In its entirety this dissertation intended to address the impact of feeding several forms of de-oiled corn distillers grains plus solubles and the effect of supplementing OmniGen-AF as a potential antioxidant source for extending beef shelf life. In study one we learned that despite the de-oiling process, greater inclusion levels (65%, DM basis) of de-oiled wet distillers grains plus solubles (WDGS) causes an increase in polyunsaturated fatty acids (PUFA) similar to the levels obtained with full-fat WDGS. Lower inclusion levels (35 and 50%, DM basis) of de-oiled WDGS have intermediate PUFA content in comparison to 65% de-oiled WDGS, full-fat WDGS …

Evaluation Of Hematological And Serum Biochemical Profiles Associated With The Supplementation Of Zilpaterol Hydrochloride To Feedlot Heifers, Sara Elizabeth Sieren

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

Supplementation of zilpaterol hydrochloride (ZH; Zilmax^®) to cattle has been suggested to have a negative impact on well-being of cattle. The objective of this study was to evaluate the hematological and serum biochemical profiles in feedlot heifers supplemented with ZH in a minimal stress environment. Heifers were randomly assigned to one of two treatment groups: Control (CON no ZH), or ZH (supplemented with ZH at 8.33mg/kg of feed on a DM basis). The study was conducted over a period of 25 d (-2 to 23), with three serum collection periods [-2 to 4 d (ZH supplementation began on …

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 …

Beef Systems Management Strategies: Calving Date Selection, Estrus Synchronization, And Post-Weaning Management, Benjamin T. Tibbitts

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

The objective of an invited review and four experiments was to evaluate production implications and economic efficiencies of beef systems strategies involving calving date selection, utilization of reproductive technology, and post-weaning management of heifers and steers. The invited review in chapter II considers factors that influence a producer’s decision on when to calve beef females. The calving date decision impacts the entire beef production cycle and must take into account any environmental conditions, available resources, and cite specific advantages and/or disadvantages. Understanding the importance of varying physiological state and nutrient demands associated with lactation and gestation is critical to optimizing …

The Effect Of Salt Reduction On The Microbial Composition And Quality Characteristics Of Sliced Roast Beef And Turkey, Chad G. Bower

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

This study analyzed the effects of salt reduction on microbiological composition and quality characteristics of deli-style turkey breast and roast beef. Turkey breast and roast beef were manufactured with four different salt concentrations: 1.0%, 1.5%, 2.0%, and 2.5% on a meat block basis in addition to sugar, phosphate, and water. Samples were cooked, chilled overnight, sliced, and packaged. On the day of slicing, samples were evaluated for water activity, cooking yield, proximate composition and percent salt. Samples were evaluated throughout 18w of refrigerated storage for pH, texture profile analysis, aerobic plate count (APC), and anaerobic plate count. Bacterial communities were …

Production And Economic Efficiencies Of Intensified Cow-Calf Production Management Systems, Jason M. Warner

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

The objective of four experiments conducted was to evaluate production and economic efficiencies of intensified cow-calf production management systems. The first experiment tested the effect of calf age at weaning on cow and calf performance and feed utilization at 2 locations. Body weight change from early to conventional weaning time was greater for early-weaned cows. Cow BCS and conception rates were not impacted by weaning. Calf BW at conventional weaning time was greater for conventionally-weaned calves than early-weaned calves at ARDC, but greater for early-weaned than conventionally-weaned calves at PHREC. Calf ADG per unit of total feed energy intake was …

Genomic Analysis Of Sow Reproductive Traits: Identification Of Selective Sweeps, Major Genes, And Genotype By Diet Interactions, Melanie D. Trenhaile

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

Reproductive traits, such as litter size and reproductive longevity, are economically important. However, selection for these traits is difficult due to low heritability, polygenic nature, sex-limited expression, and expression late in life. Marker-assisted selection may provide an alternative to increase genetic progress.

Nebraska Index Line (NIL) has been selected for litter size related traits since 1981. It is one of the main contributing lines to the UNL reproductive longevity resource population (n > 1,500), which was genotyped for 60,000 SNPs, phenotyped for age at puberty (AP), lifetime number of parities (LTNP), litter size traits, and other reproductive traits, and fed either …

Performance, Body Temperature And Blood Metabolites Of Feedlot Steers As Influenced By Environmental Conditions And Supplementation Of Zilpaterol Hydrochloride, Bradley M. Boyd

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

Trial one was conducted at the United States Meat Animal Research Center (MARC) near clay center, NE during the summer of 2014. The objective of this trial was to measure the effects of supplementing zilpaterol hydrochloride (ZH) for the final 21 days of the finishing period, and shade, on performance, body temperature, respiration rate, and mobility of finishing beef steers. Feeding ZH increased hot carcass weight, dressing percent, longissimus muscle area, and reduce USDA yield grade. Shade did not affect steer performance and did not reduce body temperature. Zilpaterol hydrochloride increased respiration rate when compared to control cattle and had …

Dietary Strategies For Mitigation Of Methane Production By Growing And Finishing Cattle, Anna C. Pesta

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

Interest in reducing methane (CH₄) emissions by cattle has increased recently. Loss of feed energy as CH₄ represents both an environmental concern and an energetic loss to the animal. Manipulation of dietary composition has proven to be an effective mitigation strategy. Experiments were conducted to evaluate the effect of several dietary characteristics on CH₄ production in growing and finishing cattle, and to develop a novel, non-invasive method for quantifying emissions from animals in a production setting. Short-term gaseous emissions of CH₄ and carbon dioxide (CO₂) were measured and the CH₄:CO_{2 …}

Effects Of Feeding Distillers Grains Throughout Different Phases Of Production On Shelf Life Of Ground Beef, Brandy D. Cleveland

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

These studies analyzed the effects of feeding distillers grains on the shelf life of cooked and raw ground beef, and how the addition of postmortem or dietary antioxidants impact shelf life.

For study one, cattle were assigned to backgrounding diets containing low or high concentrations of wet distillers grains (WDGS) and either corn gluten feed or modified wet distillers grains (MDGS) during finishing. For study two, cattle were fed one of five finishing diets; corn, wet distillers grains (WDGS), WDGS + vitamin E, WDGS + Ethoxyquin/TBHQ, or WDGS + vitamin E + Ethoxyquin/TBHQ.

Shoulder clods from each dietary treatment were …

Impact Of Wet Distillers Grains Plus Solubles And Antioxidants On A Basic Mechanism Of Beef Tenderization, Michael D. Chao

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

Feeding high levels of wet distillers grains plus solubles (WDGS) increases polyunsaturated fatty acid (PUFA) levels in beef. Perhaps, WDGS in feedlot diets increases PUFA concentration in the SR membrane, thereby altering membrane integrity, resulting in more rapid calcium leakage and improved tenderness. Feeding antioxidants may mitigate such effects. In the first study, effects of feeding 50 % WDGS on SR membrane composition, free calcium concentration and tenderness were studied. The SR membrane from steers fed WDGS were more tender, had higher free calcium concentration, had more PUFA, more phosphatidylcholine (PC), less phosphatidylethanolamine (PE) and less total phospholipids when compared …

Effect Of A Trace Mineral Injection On Beef Cattle Performance, Carmen J. Brasche

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

Adequate trace mineral status is important in beef cow/calf and replacement heifer systems because trace minerals play vital roles in reproduction, immunity and growth. Many experiments have investigated the use of a trace mineral injection containing Cu, Mn, Se and Zn (TMI) on growth and immunity of beef cattle. However, very few have investigated TMI use on reproductive performance. Therefore, five experiments, a two year cow/calf experiment, and four replacement heifer experiments were designed to investigate the use of a TMI on reproductive performance of cows and heifers, calf growth and trace mineral status of cows, heifers, and calves. The …

Corn Plant Maturity Effect On Yield And Nutritional Quality; Corn Silage Inoculation On Performance Of Cattle Fed Silage With Or Without Live Yeast Added, Cassandra A. Row

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

Corn plots were serially harvested over two years to evaluate nutrient, digestibility, and yield change as plants matured from half-milk line through black layer. In yr 1 (2013), two corn plots were used, one short season (102 d), and one normal season (111 d). Year two used two Pioneer hybrids (111 d; 112 d). Silage yield and silage DM increased quadratically as maturity increased (P ≤ 0.01). Percent NDF increased quadratically (P = 0.01), and NDF-digestibility decreased linearly (P < 0.01) as maturity increased. This study suggests there is a delicate balance between plant maturity, nutrient content, and silage yield. A finishing study using 320 yearling steers (initial BW = 417 ± 22.7 kg) evaluated the effect of using a silage inoculant or not on performance and carcass characteristics. Treatments were designed as a 2×2×2 factorial arrangement with factors being no inoculant (CON) or use of inoculant (Buchnerii spp.; B500) at silage harvest, silage fed at 15 or 40% of diet DM, and presence (LEV) or absence (noLEV) of Levucell SC yeast product fed at 14.2 g/hd/d. Performance data were analyzed with pen as the experimental unit, with 5 pens/treatment. There was a three-way interaction for final live BW, HCW, ADG, and G:F (P < 0.05). Feeding corn silage at 40% inclusion instead of 15% inclusion increased DMI and decreased G:F. At 15% silage inclusion, the B500 LEV treatment had the lowest ADG. At 40% silage inclusion all treatments were similar for ADG (P ≥ 0.06). When including silage at 15%, using B500 inoculant, the addition of LEV did not …

Changes In Corn Residue Quality Throughout The Grazing Period And Effect Of Supplementation Of Calves Grazing Corn Residue, Amanda J. Burken

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

Corn residue is an abundant feed source in Nebraska that can be utilized as an alternative winter feed. Calves were backgrounded on corn residue in order to determine gain and estimate forage intake when supplemented with distillers grains (DGS). Calves grazing the non-irrigated field gained more (1.03 kg/calf daily) when compared to those grazing the irrigated field (0.90 kg/calf daily; P < 0.01). In year 1, a quadratic effect for intake of DGS was present (P < 0.01) while year 2 observed a linear effect for increasing level of DGS (P < 0.01). The nutritional quality of corn residue was evaluated over time in order to determine changes in blade/sheath, cob, husk/shank and stem. Minimal changes in DM of the forage components occurred was grain reached 15.5% moisture. Digestibility of the blade/sheath declined linearly over time (P < 0.01) while the husk remained constant (P = 0.40). Cob digestibility decreased quadratically (P < 0.01) throughout the sampling period with few changes once grain reached 15.5% moisture. Differences observed in the digestibility of the blade/sheath were attributed to the effects of weathering. A third set of trials was conducted to evaluate the effects of by-product supplementation of calves grazing irrigated corn residue and supplemented with DGS or continuous access to lick tubs. The DGS treatment gained more (0.62 kg/calf daily) than the lick tub treatment (0.38 kg/calf daily; P < 0.01). Calves offered DGS consumed more supplement as a percentage of BW (0.52%) when compared with calves offered lick tubs (0.36%; P < 0.01) on a DM basis. Calves supplemented with DGS had a higher supplement efficiency (46.3% to 42.9%, DM basis) although no differences were present between treatments (P = 0.49). When analyzed on an OM basis, however, calves offered lick tubs had a numerically higher supplement efficiency (50.4%) in comparison to calves …

New Approaches To Corn Silage Use In Beef Cattle Finishing Diets, Dirk Burken

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

Cattle feeders are considering alternative feedstuffs to replace expensive corn grain and decrease rations costs. Feeding corn silage allows cattle feeders to take advantage of the entire corn plant at a time of maximum quality and tonnage as well as secure substantial quantities of roughage and grain inventory. Distiller’s grains have proven to be economical and are now a commonplace ingredient in feedlot finishing diets. Experiments were conducted to determine the effects of feeding increased concentrations of corn silage in replacement of corn grain in finishing diets containing distillers grains. Feedlot gains and gain:feed ratios were reduced as corn silage …

Effects Of Stocking Rate On Forage Nutrient Composition Of Nebraska Sandhills Upland Range When Grazed In Early Summer And The Effects Of Grazing On Nebraska Sandhills Meadow Forage Nutrient Compostion, Jared V. Judy

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

The objectives of this research were to 1) evaluate the effects of stocking rate on forage nutrient quality 2) quantify the relative proportions of current vs. previous year growth being consumed in early summer upland range pastures and 3) determine how grazing effects forage nutrient quality in subirrigated meadows in the Nebraska Sandhills. Experiment 1 was a two year study conducted on the experimental upland range paddocks at Gudmundsen Sandhills Laboratory. Twelve 2-hectare paddocks were assigned one of three treatments stocked at 0 (control), 0.57 (light), and 0.85 (heavy) AUM/ha. Ten 0.25 m² quadrats were clipped per paddock during …

Effects Of Feeding Distillers Grains Throughout A Yearling Heifer Beef Production System On Meat Quality Attributes And Effects Of Omnigen – Af With Ractopamine Hydrochloride On Animal Performance And Beef Carcass Characteristics Of Feedlot Steers, Kelby M. Sudbeck

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

Heifers (n = 229; 225 kg ± 2) were used in a 2 x 2 x 2 factorial to determine the effects of longterm exposure to corn distillers grains plus solubles (DGS) on meat quality characteristics. Factors included supplementing 0.91 kg (LW) or 2.3 kg (HW) modified DGS (MDGS) while grazing corn stalks; 0.6% BW dry DGS (SS) daily or none (NS) during summer grazing; and finishing diet containing 40% wet corn gluten feed (CGF) or 40% MDGS (DGF) on a DM basis. An interaction was observed within CGF for discoloration, with SS increasing discoloration 30%; but no differences between …

Genetic Parameter Estimates And Breed Effects For Calving Difficulty And Birth Weight In A Multi-Breed Population, Cashley Ahlberg

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

There are multiple breeds of beef cattle available to utilize in breeding systems to maximize production and economics. Calving difficulty (dystocia) is a significant cost to beef production and is more prevalent in first-calf heifers. The objectives of this study were to estimate genetic parameters and breed differences for calving difficulty and birth weight as a first step towards the development of across-breed adjustment factors for calving difficulty.

Two models were employed to analyze birth weight (BWT) and calving difficulty (CD) recorded on 4,579 first parity females from the Germplasm Evaluation program at the U.S. Meat Animal Research Center (USMARC). …