Animal Sciences Commons^™

Evaluating The Motivations Of Participants In Online Equine Extension Courses, Sarah Vos

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

Traditional program evaluations emphasize participant demographics, knowledge gain, behavior change, and program impact. However, evaluating participant motivation can provide addition insight into why participants enroll in extension programs and help explain participant engagement and persistence throughout a program. The purpose of this study was to evaluate participant motivation in two online equine extension courses and examine potential relationships between motivation, demographics, and course delivery method, and describe participant engagement in Virtual Horse Judging Camp (VHJC). This cross-sectional study utilized convenience sampling of participants in two online equine extension courses, Horse Adult Leader Training and Educational Resource (HALTER) and VHJC. The …

Improving Genomic Prediction For Feed Efficiency Traits In Beef Cattle Using Microbiome As An Intermediate Omics, Egodage Bhagya Sewwandi Samarakoon

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

Feed efficiency traits, including feed conversion ratio (FCR), average daily gain (ADG), and average daily dry matter intake (ADDMI), are economically important in beef cattle production. Emerging evidence suggests that host genetics influences feed efficiency traits through the microbiome. This study evaluates the integration of microbiome data as an intermediate layer in the Neural Network Mixed Model (NNMM), which hierarchically models genotype–microbiome–phenotype relationships as a unified regulatory network to improve genomic prediction accuracy. To reduce the computational burden of NNMM, microbiome features dimension were reduced using principal component analysis (PCA) and direct feature selection of top-ranked open reading frames (ORFs) …

The Detection Of Morbidity Using A Remote Sensing Ear Tag On Newly Received Steers And Feedlot Performance And The Effects Of Feeding Experior And Optaflexx On Carcass Characteristics And Meat Tenderness In Beef Steers, Lauryn O. Smidt

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

Two experiments were conducted to evaluate the effects of remote sensing health technology and growth-promoting feed additives on feedlot cattle performance, health outcomes, and carcass characteristics. In the first study, 638 crossbred steers (initial BW = 270 kg; SD = 18.6 kg) were used in a randomized block design to assess the effectiveness of a remote sensing ear tag (RST; HerdDogg, Seward, Nebraska) versus conventional pen-rider observation (PR) for detecting morbidity during a 35-d receiving period and subsequent 180-d finishing period. No differences were detected between PR and TAG for ending BW, average daily gain (ADG), dry matter intake (DMI), …

Carcass Mass And Cooling Dynamics As Determinants Of Beef Color, Tenderness, And Dark-Cutting Risk, Grace C. Johnson

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

Discoloration in beef has important implications to the beef industry. Dark-cutting (DC) beef remains one of the most economically significant color defects; however, industry prevalence has only marginally declined (≈ 0.1%) despite mitigation efforts. This lack of improvement largely stems from research focused on pre-harvest stress and glycogen depletion leading to dark, firm, and dry (DFD) beef. However, not all darkcutting beef originates from DFD phenotypes. Atypical dark-cutting (ATDC) phenotypes have recently been observed and do not exhibit the classic metabolic indicators of DFD. This trend coincides with steadily increasing carcass weights in the beef industry and raises the possibility …

Lipid Deposition In Beef Cattle, Kyra L. Elliott

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

Both the amount and types of lipid deposition in beef cattle are key determinants of carcass value and meat quality. Amounts of intramuscular, subcutaneous, and visceral fat influence carcass grading outcomes, palatability, and composition traits that are important to beef producers as well as consumers. The objectives of this thesis were to: 1) compare beef grading camera estimates of intramuscular fat to amounts of chemically extractable lipid, 2) characterize the lipidomes of beef intramuscular fat, subcutaneous fat, and lean muscle using shotgun lipidomics, and 3) identify and characterize a novel genetic variant in cattle that may have important implications for …

Characterization Of Activity Changes In Gilts During Estrus Using The NuTrack Livestock Monitoring System, Emily P. Aquino

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

Early and accurate detection of estrus in replacement gilts is essential for reproductive success and to ensure efficient production. The objective of this study was to evaluate activity changes occurring relative to first estrus of gilts and subsequent cycles. At ~ 110 days of age, 112 gilts were randomly assigned to 14 pens and placed under continuous video monitoring until the end of the trial at ~ 200 days of age. Daily boar exposure (~ 10 minutes per day) began at ~ 122 days of age. During this period, recorded observations included vulva scores (based on swelling and redness), mounting …

Evaluation Of Maternal Bovine Appeasing Substance Administration And Feed Access Time On Finishing Cattle Performance, Behavior, And Carcass Characteristics, Carsten L. Loseke

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

Novel products and bunk management techniques may significantly influence economically relevant performance metrics of feedlot cattle. The objective of the first experiment was to evaluate maternal Bovine Appeasing Substance (mBAS) administration on performance, carcass, health, and cortisol outcomes of yearling steers. Steers (n = 1,754, initial BW = 423 kg, SD = 25 kg) were received and assigned to pens for treatment allocation. Steers received either 10 mL of the mBAS or a mineral oil placebo at initial processing and reimplant. Hair samples were collected from a subset (n = 4 steers/pen) on d 0 and d 14. …

Integrating Growth Performance And Pathogen Detection To Investigate Disease Resilience In Commercial Swine, Emmalise Hope Marie Meyer

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

Disease resilience is an important trait in commercial swine production, influencing both animal health and growth performance under natural disease challenge. The primary objective of this study was to integrate growth performance data with longitudinal pathogen detection to better understand factors contributing to disease resilience in commercial pigs. A population of 1,014 pigs across four batches was monitored from weaning through the grow-finish phase, with body weights collected to calculate average daily gain (ADG). Genome-wide association analyses were conducted using BayesC and BayesIM approaches to identify genomic regions associated with growth performance. Longitudinal pathogen surveillance was performed using pen-level oral …

Tail Biting In The Nursery: Evaluating Postural, Spatial, And Behavioral Differences Between Tail Biter And Victim Pigs, Storey L. Forster

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

This study examined behavioral differences among pigs classified as tail biters, victims, or neutral during the nursery period. A total of 192 undocked nursery pigs were assigned to eight pens and monitored for 30 days using the NUtrack system. Tail biting events were identified from video observations, and pigs contributing to the top 25% of observed tail biting activity were classified as tail biters. Based on weekly tail scoring, pigs assigned a maximum tail injury score ≥ 2 were classified as victims. All other pigs were considered neutral. A total of 700 tail biting events were observed. Thirty-eight pigs …

Application Of High-Pressure Processing To Improve The Color Of Dark Beef, Kara Ann Reynolds

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

Deviation of beef from the bright cherry-red color preferred by consumers is often discounted or discarded at retail, resulting in substantial annual economic loss to the beef industry. One such deviation is dark cutting beef, which is characterized by a darker lean appearance that is undesirable to consumers and often rejected. Similarly, beef from mature cattle tends to exhibit a darker surface color, which can also reduce consumer acceptability. High-Pressure processing (HPP) has been investigated as a strategy to improve the color of dark cutting beef. Previous studies have focused on identifying pressure levels and holding times that optimize color …

Factors Affecting The Efficacy Of Free Choice Vitamin & Mineral Supplementation Programs, Tanner K. Wansing

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

While free choice vitamin and mineral supplements are widely used within the cow/calf sector, large knowledge gaps exist around the proper management of those supplements. This thesis discusses two factors affecting the efficacy of supplementation. The first interest was the stability of vitamin A when stored with a common free choice mineral supplement. This research addressed a critical data gap by generating information on vitamin A stability within the beef industry, as current data are predominantly based in the swine industry. Vitamin A was discovered to be stable until 4 months of storage regardless of storage conditions, whereas after 4 …

Evaluating Management Strategies And Technology To Improve Grazing Efficiency, Thomas E. Aquino

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

Increasing land costs and labor constraints continue to challenge beef producers. More intensive practices can increase harvest efficiency; however, many producers are deterred from implementing them due to increased labor and management considerations. Virtual fencing (VF) may provide a reduced labor alternative to traditional fencing for managing intensive grazing. This dissertation evaluated management strategies and VF technology to improve grazing efficiency of stocker cattle systems. In Experiment 1, VF was used to effectively manage groups of steers grazing in adjacent paddocks separated by only virtual boundaries. There was no difference in VF containment (99%) when steers were grazing co-fenced, with …

Evaluation Of Palm Oil As An Ingredient In Finishing Beef Cattle Diets On Performance, Carcass Characteristics, And Meat Quality, And The Composition Of Spayed Heifers To Intact Heifers Fed Melengestrol Acetate On Feedlot Performance And Carcass Characteristics, Tate S. Johnson

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

Heifers represent a large proportion of cattle placed in feedlots, making pregnancy management an important consideration for maintaining performance and carcass value. Melengestrol acetate (MGA) is commonly included in feedlot diets to suppress estrus and prevent pregnancy in intact heifers during the finishing period. Alternatively, spaying has historically been utilized as a management practice to allow heifers to graze alongside breeding cattle without the risk of pregnancy. Despite its historical use, there is limited contemporary research comparing the growth performance and carcass characteristics of spayed heifers with intact heifers managed with MGA under modern feedlot conditions. Therefore, a commercial study …

Exploratory Evaluation Of Handler Performance And Processing-Related Outcomes During Cattle Handling, Morgan Marquardt

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

Animals have several critical roles in society, including the production of food and fiber, and companionship. Contact with animals has been shown to benefit human physical and mental health, yet little research has investigated the impact that humans have on animals. Handler skill may considerably affect the extent to which humans influence animal health and wellbeing, and this may be a critical consideration for animal agriculture. Objective assessment of cattle handler skill has received limited attention in the scientific literature, despite its importance to human safety and animal welfare. When compared to less skilled handlers, highly skilled cattle handlers may …

Evaluation Of Ramp Instead Of Forage During Grain Adaptation And Different Sorghum Varieties On Enteric Methane Production From Cattle, Jack T. Fort

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

Two experiments were conducted to evaluate the use of RAMP (Cargill Corn Milling, Blair, Nebraska) compared with traditional forage-based adaptations on methane (CH₄) and carbon dioxide (CO₂) emissions, performance, and carcass characteristics. Experiment 1, 64 yearling British × Continental steers (initial BW = 423 ± 6 kg) were adapted using 100% RAMP (RAMP) or a traditional forage diet (CON; 43% forage) before transitioning 22 d to a common finishing diet containing 65.6% steam-flaked corn. Emissions were measured in paired replications using a two-chamber indirect calorimetry barn. During adaptation RAMP did not affect CH₄ production (g/d; …

Impact Of Constant Versus Variable Inclusions Of Modified Distillers Grains Plus Solubles On Feedlot Cattle Performance And Carcass Characteristics And Impact Of The Frequency Of Varying Modified Distillers Grains Plus Solubles Inclusions In Feedlot Diets On Performance, Carcass Characteristics, Feeding Behavior, And Ruminal Ph Of Finishing Steers, Paige M. Madison

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

Inconsistent availability or supply of distillers grains (DGS) can cause more variation in DGS inclusions throughout the feeding period. Two feedlot experiments evaluated the effects of varying inclusions of modified distillers grains plus solubles (MDGS) in feedlot diets. Beef steers (n = 400; initial BW = 287) were used in a 2 × 2 + 1 factorial experiment with treatments including: control with no MDGS compared to 2 inclusions (10% and 25%) of MDGS diet inclusions fed consistently or variably. No interactions were observed between MDGS consistency and inclusion for any performance or carcass characteristics (P > 0.10), so …

Integrating Innovative Sensing And Ground Measurements For Forage Mass Estimation In Rye Pasture, Pedro Henrique Jota Fernandes

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

The United States beef industry relies on forages to provide up to 80% of total lifetime dry matter intake, making accurate forage mass estimation essential for determining stocking rates, improving grazing efficiency, and supporting economic sustainability. Traditional methods to quantify forage mass, however, are time-consuming and labor-intensive. This thesis presents research efforts to achieve accurate forage mass estimation in cereal rye pasture by integrating novel sensing technologies.

Chapter 1 reviews the importance and evolution of forage mass estimation methods, from destructive clipping to indirect approaches based on canopy measurements. It then introduces remote sensing, from proximal tools to drone- and …

Investigation Of Changes In Exotic Bird Serum Vitamin D Levels Between Indoor And Outdoor Housing, Alexander J. Marley

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

Vitamin D is a fat-soluble vitamin that is directly related to sunlight and is involved in multiple physiological processes including calcium metabolism, feather quality, and chick development. Most vertebrate species are capable of both absorption of exogenous vitamin D and internal synthesis of vitamin D, with vitamin D3 (cholecalciferol), being more accessible and bioactive in bird species. In exotic bird species, dietary requirements for vitamin D3 are largely unknown, and the ability to maintain adequate serum concentrations of vitamin D3 metabolites without direct sunlight exposure also requires evaluation. Concerns arise in situations where individuals may be housed indoors for extended …

Associations Of Variation In Mtdna With Feed Efficiency In Beef Cattle And The Evaluation Of Transcriptomic Changes In Fetal Kidney Due To Hydrallantois, Lauren Elizabeth Seier

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

Project 1 focused on the central role that mitochondria play in ATP production, highlighting that variation within the mtDNA may influence feed efficiency. Variation in the mitochondrial genome was uncovered, and associations with feed efficiency in beef cattle were identified. Growth and feed intake phenotypes, as well as low-pass sequencing, were collected on beef steers across two populations. Protein coding variants were identified and used to classify animals into mitochondrial haplotypes. A linear mixed model was employed, which detected a significant association between mitochondrial haplotype and DMI. A significant haplotype with a variant in Complex I was associated with reduced …

The Effect Of Diet Formulations Containing Different Protein Sources On Energy And Nitrogen Utilization In Lactating Jersey Cows, Kortney Ann Harpestad

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

It is well understood that lactating dairy cows require metabolizable protein (MP) for milk yield and milk protein synthesis. Diets with conventional feed sources like corn and soybean meal (SBM) may not sufficiently meet all MP and amino acid (AA) requirements so supplementation with more rumen undegradable protein (RUP) rich feeds or rumen-protected AA can be fed to support animal performance. The growth trajectory of biofuels has resulted in dramatic increases in the production of feeds like heat treated soybean meal (HTSBM). While the chemical composition of this product is understood, there is a need to better understand how HTSBM …

Stereotypic Behaviors And Physiological Indicators Of Stress Occur In Horses With Restricted Durations Of Turnout, Elizabeth E. Rodgers

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

The confinement of horses to stalls with limited or no turnout time restricts their natural roaming behaviors, which potentially increases stress and behavioral stereotypies. This study investigated the impact of turnout duration on behavioral and physiological stress indicators in healthy horses. Adult horses (n = 11) were enrolled in a 3 treatment (0-, 15-, and 60-minute turnout/day) Latin square design, including 3 12 d experimental periods over 6 weeks. Horses were acclimated to turnout (24.38 x 64.01m indoor arena) and stalls (2.74 x 4.87m - 3.66 x 3.66m) stalls prior to data collection on day 1. Experienced handlers managed …

Digestibility, Palatability, And Nutrient Composition Of Three Species Of Whole Prey In Three Species Of Snakes, Morgan R. Kienzle

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

Snakes in human care often lack diversity in the diet. Rodents account for the majority of meals, while wild snakes are consuming a varied diet composed of multiple different whole prey species. By feeding only one species of prey, the chance of nutrient deficiencies and other health concerns increases. To promote variety in the managed diet, two commercially available whole prey species (mice (Mus musculus) and chicks (Gallus spp.)) and one novel species (Seba’s short-tailed bats (Carollia perspicillata)), were analyzed for their dry matter (DM), organic matter (OM), crude protein (CP), crude fat …

Evaluation Of Two Different Sweet Bran Products On Beef Cattle Digestion Characteristics And A Review Of Ramp As An Alternative Step-Up Program, Emily K. Hoefling

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

Two Sweet Bran products were evaluated at 13%, 18%, and 23% inclusion of the diet on total tract digestibility and rumen fermentation parameters. Seven ruminally cannulated, heifers were used in a 6 x 7 row-column design with 21-d periods consisting of 16-d adaptation period followed by a 5-d collection. Dietary treatments were designed in a 2 x 3 factorial arrangement with 6 periods. Factors included two Sweet Bran products that differed in particle size (Sweet Bran-SP; GMD = 1.79 mm or Sweet Bran-LP; GMD = 2.51 mm) and three dietary inclusion (13%, 18%, or 23% of diet dry matter). The …

Methane Mitigation And Its Effects On Energy Utilization In Lactating Dairy Cattle, Shan C. Sherwood

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

Improved methane (CH₄) mitigation strategies are needed to achieve the greenhouse gas emission goals of the dairy industry. The first experiment was conducted to evaluate the effects of feeding black cumin (Nigella sativa) seed oil and acetate (BCA) on CH₄ production and whole-animal energy utilization. Twelve dry Jersey cows were used in a 2-period crossover design study with 28d periods. The BCA treatment was compared to a control diet with corn oil. Both BCA and corn oil were added to the base diet as a top dress. Results from this study did not show any …

Small Cereal Grain Silage Producer Practices And Key Factors To Consider For Operations, Alexa R. Simons

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

The use of small grain silage to feed livestock has grown in popularity, although the more common source of silage is annual corn. A benefit of producing small cereal grain is double cropping, harvest a forage source in the spring prior to planting the summer annual crop. Although the cereal and corn silage processes are similar there are key differences within management decisions for producers. Objective one was to understand current management decisions from Nebraska producers pre- and post- fermentation surveys along with small cereal silage samples were analyzed. Some best management practices such as the dry matter (DM), DM …

Precision Feeding Methods To Increase Nitrogen And Energy Utilization In Lactating Dairy Cows, Chloe Emily Moss Harris

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

The environmental and economic costs of overfeeding N to dairy cattle are a challenge in today’s dairy industry. Two studies were conducted to address new opportunities for precision feeding N, which is a strategy where producers strive to feed cows the precise amount of N and amino acids that meet their individual requirements.

The objective of the first study was to evaluate the effects of supplementing a rumen protected methionine (RPM) product via automatic milking system (AMS) concentrate on milk protein yield in lactating dairy cows. Fifty-one cows were randomly assigned to control (no RPM) or treatment groups. Milk yield …

Using High-Pressure Processing To Improve The Quality Of Dark-Cutting Beef, Ashley A. Hahn

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

Previous studies have shown high-pressure processing (HPP) can be utilized to improve lean color of dark-cutting beef color by increasing the lightness and redness of steaks. However, the optimal parameters of length of time product is held under pressure and at which pressure must be applied have yet to be fully defined. Furthermore, the impact of HPP on color labile muscles in dark-cutting beef are currently unknown. Therefore, two studies were designed and specific efforts were focused on first defining optimal parameters for color stable muscles, followed by determining the effect of HPP on dark-cutting color labile muscles.

In the …

Relationship Between Host Genomics And Microbiomics In Beef Cattle, Andrew D. Lakamp

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

As sequencing technology becomes more affordable and throughput increases, microbiome information is becoming more readily available. For beef cattle selection, microbial information has a variety of uses including being a target for genetic prediction or used as a means to explicitly describe additional phenotypic variability in other traits.

Infectious bovine keratoconjunctivitis (IBK), commonly known as pinkeye, is a disease that infects the ocular surface and surrounding tissue which is an animal health and producer economic concern. Vaccinations have shown to have variable effectiveness, while limited genetics studies have suggested that direct genetic selection for resistance would be slow. Therefore, an …

Examining Factors Of Variance In Energy Metabolism Of Dairy Cattle, Addison L. Carroll

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

Variation is thought to occur in the use of dietary energy for production in dairy cattle. First, variance can be observed when new methane mitigation strategies are fed resulting in increased H₂ output potentially resulting in downstream effects on estimates of heat production via the Brouwer (1965) equation. Therefore, in chapter 3 a review was created to systematically describe the mathematics and theory behind the Brouwer equation, and rederive a heat production equation to integrate H₂ production. Results indicate heat production using the classical Brouwer equation (1965) relative to the rederived equation resulted in an overestimation of heat …

Impacts Of Annual Forage Management On Grazing Cattle Performance And Carrying Capacity, Shelby Davies Jenkins

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

Rapid conversion of historical grasslands to cropland in recent history has led to limited perennial pasture availability and an increase in cost of pasture rent. Annual forages are an alternative grazing source. Many annual forages can grow and accumulate stockpile following summer harvest of wheat. Strip grazing is often suggested to increase grazing efficiency of stockpiled forages. To evaluate this, a stockpiled mixture of annual forages were either strip grazed or grazed continuously in the fall and winter. The mixture contained oats and rapeseed in the first year and a diverse warm season annual mixture in the second. Strip grazing …