Life Sciences Commons^™

Interaction Of Urea With Frequency And Amount Of Distillers Grains Supplementation For Growing Steers On A High Forage Diet, Haley F. Linder

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

Two studies were conducted to determine interactions of urea inclusion to a dried distillers grains plus solubles (DDGS) supplement fed at two amounts and two frequencies to steers on a high forage diet. In Exp. 1, 120 steers were fed individually for 84 d. Steers received ad libitum grass hay and 1 of 8 treatments. Supplement was fed either every day (D) or 3x/week (ALT), amount of supplement fed was 6.36 kg/week (LO) or 12.73 kg/week (HI), and contain either no urea (-U) or 1.3% urea (+U). Hay DMI and steer BW were measured. In Exp. 2, 8 ruminally cannulated …

Improving The Accuracy Of Genomic Predictions: Investigation Of Training Methods And Data Pooling, Johnna Baller

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

One of the primary factors in the response to selection is the accuracy of selection. This study focused on methodologies to predict breeding values (BV) accurately within multi- and single-step genomic evaluations. Factors including cross-validation methods, dependent variables, and genotyping strategies were assessed on the accuracy of genomic BV while using multi-step prediction in real and simulated data. In both cases, random clustering led to largest estimated accuracies compared to clusters based on k-means, k-medoids, and principle component analysis, but differences in bias were not detected. Using deregressed estimated BV (EBV) to estimate SNP effects led to larger accuracies and …

Energy Metabolism In Jersey Cows: Improving Our Understanding Of Energy Requirements And Utilization, Dennis Morris

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

Energy is the most limiting nutrient for high producing lactating dairy cows and improving our understand of factors affecting energy supply should improve our ability to estimate net energy of lactation (NE_L), milk production, and tissue accretion. To achieve this object, firstly, three experiments were completed to determine 1) maintenance energy requirements; 2) factors affecting heat production; and 3) the relationship between urinary N and energy excretion. Three additional experiments using lactating Jersey cows were completed to evaluate energy utilization of diets varying in 1) supply of Lys and His; 2) fatty acids (FA) and …

Influence Of Strategic Supplementation And Genetic Potential For Milk Yield On Forage Digestibility, Amino Acid Utilization, And Livestock Production, Tasha M. King

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

When consuming low-quality forages or at times when nutrient demands are high, ruminants may be unable to meet these requirements resulting in a state of negative energy balance. With feed costs contributing a large portion of production costs, providing dietary nutrients to maintain energy balance must be done so strategically. Additionally, producers must ensure consistent reproductive performance and offspring weaned to maintain a successful livestock enterprise. The objective of these studies was to evaluate the effect of glucogenic precursor supplementation and milk yield on forage digestibility, amino acid utilization, and livestock production. In experiment 1, a metabolism study was conducted …

Advancing The Science Of Dry-Aged Beef, Felipe Azevedo Ribeiro

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

In order to tightly control dry aging environmental conditions, we designed and built a computerized dry aging system that is capable of measuring and precisely controlling relative humidity (RH; ± 1%), temperature (± 0.5 °C), air flow (± 0.015m³/min), and mass loss (± 5 g). This dissertation addressed the effects of RH and ultimate pH on meat quality and sensory attributes of dry-aged beef. In study one, we learned that wet-aged steaks had higher L* (P = 0.01), a* (P = 0.03), and b* values (P < 0.001), lower discoloration scores (P < 0.05), and lower TBARS (thiobarbituric acid reactive substance) values (P = 0.03) than dry-aged treatments. Under prolonged …

Characterization Of Protein And Fat In Dairy Feeds And Implications On Digestibility And Milk Composition, Kassidy Buse

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

A variety of feedstuffs are used to comprise dairy rations, each with their own nutritional contributions. In order to best utilize these feedstuffs to maximize production, characterization of their chemical composition is needed. Through the use of both in vitro and in situ methods, not only can the composition of the feed be determined, but also its digestibility. Also, because of the important role they play in human health, omega 3 fatty acids have received increasing attention. Most individuals consuming Western diets do not meet the recommended requirement for omega 3 fatty acids, and one way to improve that is …

Effects Of Ndf Digestibility On Lactating Jersey Cows: Observed And Modeled Performance, Kirby Krogstad

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

Improving the digestibility of fiber and our understanding of how to feed it will optimize the ruminants’ niche in our society, which is to convert human inedible products to high quality protein in the form of meat and milk. Neutral detergent fiber (NDF) digestibility has been studied and modeled for decades, but it is increasingly important as livestock production is scrutinized for resource use and sustainability. Increasing the amount of NDF fed and improving models of NDF digestibility will improve sustainability by increasing the precision at which we feed livestock which results in less nutrient and greenhouse gas (GHG) emissions. …

The Role Of Postnatal Adrenergic Manipulation In The Mediation Of Fetal Programming Adaptions In Growth And Skeletal Muscle Glucose Metabolism That Persist In The Juvenile Iugr-Born Lamb, Rachel L. Gibbs

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

Our 1^st study assessed growth deficits in IUGR juvenile lambs and the benefits of treatment with adrenergic and inflammatory mediators. Growth metrics including bodyweight, rate of gain, and crown-rump length were diminished by placental insufficiency-induced IUGR through 2 mo. of age but were recovered by daily clenbuterol or curcumin supplementation. Body composition metrics indicated by bioelectrical impedance, proximate analysis, and loin size revealed that fat-free lean mass, specific muscle group sizes, and protein-to-fat ratios were reduced in unsupplemented IUGR lambs but recovered to or even past controls in clenbuterol-supplemented lambs. From these findings, we conclude that IUGR impairs postnatal …

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 …

Energy And Amino Acid Metabolism In Lactating Jersey Cows Consuming Feed Byproducts, Kyle Mclain

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

Animal protein byproducts are high bypass proteins commonly used in the dairy industry. These bypass proteins can escape the rumen to supply additional amino acids needed to support milk and protein yield. Two of the more popular animal protein byproducts used in the dairy industry are blood meal and hydrolyzed feather meal. In the first experiment, two flow meters were compared using headbox-style calorimeters. The objectives of the first study were to test mass flow meter (MFM) and volumetric flow meter (VFM) by measuring O2 consumption and CO2 production and to illustrate the effects of incomplete gas recovery on estimated …

Impact Of Cow Size And Validation Of An Electronic Feeder To Optimize Resources In Beef Production Systems, Rob Ziegler

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

Optimizing beef production systems is critical in the longevity of an enterprise. In a time of rapid change and innovation, there are increasingly more opportunities to improve efficiency of livestock production by taking advantage of new technologies. Furthermore, production environments vary drastically in all segments of the beef industry, which influence feed resource availability. Therefore, it is critical to realize the cow type that excels in a given production environment according to management objectives. To gain a better understanding of the optimal cow type in the Nebraska Sandhills, a retrospective analysis was conducted to evaluate increasing cow body weight (BW) …

Impact Of Diet And Quality Grade On Meat Quality Characteristics And Their Relationship To Oxidative Stress, Nicolas Bland

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

Marbling and tenderness in meat are some of the most impactful factors for the consumer eating experience. The cause of the relationship between marbling and tenderness is still unresolved. This study was conducted to evaluate the effects of feeding different types of processed corn, with or without distiller grains on oxidative stress, and how that relates to tenderness and shelf life of beef steaks of differing quality grades. Steers (n= 240) were finished on dry rolled corn (DRC), DRC + 30% dried distillers grains (DDGS), steam flaked corn (SFC), or SFC + 30% DDGS. Cattle were fed 10 per pen. …

Evaluation Of Maternal Diet And Its Effect On Milk Composition And Piglet Health And Growth Performance, Shana Barnett

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

Both graduate research and graduate teaching duties work together to help to develop a graduate student’s skills both in the classroom and on their research experiments. Being both a GTA and GRA allows a student to form more sound hypotheses, connect better with students, and better understand their own research.

During the time as a GTA and GRA four surveys were developed to analyze different groups of students and their learning environment and two animal experiments were conducted to evaluate maternal diet and its effect on milk composition and piglet health and growth performance

The surveys given to students consisted …

Evaluation Of Novel Additives And Corn Silage As Natural Alternatives To Antibiotics For The Prevention Of Ruminal Acidosis And Liver Abscesses In Beef Finishing Cattle, Hannah C. Wilson

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

Receiving and finishing experiments were conducted to evaluate a non-antibiotic alternative for control of liver abscesses. There was no impact of Ramaekers Immune Primer (RAM; a proprietary blend of vitamins, minerals, prebiotics, and probiotics) treatment on overall performance. Compared to tylosin, RAM was not efficacious in reducing total liver abscesses.

A feedlot study was conducted comparing a natural feed additive (essential oils blend) at varying corn silage inclusion levels on receiving and finishing cattle performance. Inclusion of EO had no effect on performance. Feeding corn silage at greater inclusions decreased daily gain and feed efficiency but increased final body weight …

Translational Genomics For Improving Sow Fertility, Hiruni R. Wijesena

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

Sow fertility traits, such as litter size and number of lifetime parities produced (reproductive longevity), are economically important. Selection for these traits is difficult because they are lowly heritable, polygenic, sex-limited, and express late in life. Age at puberty is an early indicator of reproductive longevity. Gilts that achieve puberty at an early age have a greater probability to produce more parities over their lifetime. However, measuring age at puberty is time consuming and tedious. Identifying pleiotropic polymorphisms that affect age at puberty and other fertility traits, including reproductive longevity, could help to improve the accuracy of genomic prediction for …

Investigating Microbiomes And Developing Direct-Fed Microbials To Improve Cattle Health, Alison Bartenslager

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

Over the last decade, global beef production has increased to meet the protein needs of the growing population. As a result, the intensification of beef cattle production systems has resulted in broad spectrum prophylactic use of antibiotics and growth promoting agents. With increased concern around antimicrobial resistance (AMR) and emergence of novel pathogenic strains of bacteria, it is critical to understand disease progression and associated changes in the microbiome to develop novel therapeutic alternatives to reduce antibiotic use and control disease. One such approach that is currently being investigated is the development of novel direct-fed microbial strains to outcompete pathogens …

Heat Stress-Induced Deficits In Growth, Metabolic Efficiency, And Cardiovascular Function Coincided With Chronic Systemic Inflammation And Hypercatecholaminemia In Ractopamine-Supplemented Feedlot Lambs; Atypical Cyclicity At Puberty In Beef Cows Is Associated With Early Deficits In Muscling, Metabolic Indicators, And Myoblast Function In Offspring But Does Not Impact Feedlot Performance., Rebecca M. Swanson

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

Our 1^st study evaluated the effects of b-adrenergic agonist (ractopamine) supplementation on growth, health, and wellbeing in heat-stressed feedlot wethers. Chronic heat stress impaired growth, metabolism, and wellbeing even when the impact of reduced feed intake was eliminated by pair-feeding. We observed systemic inflammation and hypercatecholaminemia that were likely mediators of these deficits. Moreover, ractopamine did not diminish any wellbeing indicators and improved muscle growth without worsening the effects of heat stress.

Our 2^nd study assessed the effects of pubertal cyclicity (weaning to 1^st breeding) in cows on myoblast-mediated muscle growth, metabolism, and growth efficiency of their …

Comparison Of Comprehensive Health Score In North American Housed Giraffe And Free-Ranging Giraffe From South Africa, Haley Beer

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

Stress is evident in many animal species and has been correlated to disease prevalence. During stressful events, allostasis is initiated by physiologic systems to maintain or reestablish homeostasis to protect an organism’s viability. Over time, the acclimation to frequent stress causes systematic dysregulation, leading to the phenomena of increased allostatic load. Allostatic load has been assessed in animal species via serum through selection of representative, multi-system biomarker indices. Perception and number of stress events may impact dysregulation severity, yielding allostatic load as a predictive tool. However, the allostatic load methodology poses application limitations to individuals without historical data and those …

Evaluation Of Protein Sources And Holstein Finishing Systems For Organic Beef Production And A Comparison Of Single And Dual Implant Strategies In Finishing Heifers, Elizabeth Schumacher

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

Two in situ experiments were conducted to compare the rumen undegradable protein content (RUP) and RUP digestibility of conventional and organic field peas, fish meal, dehydrated alfalfa, and soybean meal. Significant differences were detected between feed samples in both studies for all variables measured. Variation existed between sample types but the data did not suggest that organic and conventional feeds are different when processed with the same methods. A performance experiment was conducted utilizing individually fed Holstein steers comparing the effect of RUP source in a simulated organic production system. Dietary treatments were: no supplemental protein (NONE), field peas (FP), …