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 …

Effect Of Accelerated Adaptation Programs On Feedlot Performance And Health Of Steers Drenched With Megasphaera Elsdenii And Quantifying And Partitioning Multi-Year Carbon Dioxide And Methane Fluxes In A Grazed Temperate Pasture, Rebecca Mcdermott

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

With strong consumer demand for beef and increasing concern about the environmental impacts of beef production, improving production efficiency and advancing the understanding of the environmental footprint are critical for the long-term sustainability of beef production systems. The first experiment evaluated the effect of accelerated adaptation strategies, using energy intake and cattle behavior, on feedlot performance, carcass characteristics, and health of yearling steers drenched with exogenous Megasphaera elsdenii. Accelerated adaptation programs (0, 7, or 14 d transition to 100% finisher) were compared to a traditional 21-d adaptation. Dry matter intake responded quadratically across treatments, with the greatest intake observed in …

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 …

Gaining Mussel: Evaluating Reintroduction Success Of Native Freshwater Mussels In Nebraska And Eastern Wyoming, Travis A. Moore

School of Natural Resources: Dissertations, Theses, and Student Research

Freshwater mussels are one of the most imperiled groups of organisms in North America, with over two-thirds of species considered threatened, endangered, or of special concern. These long-lived bivalves are essential to stream ecosystems, acting as filter feeders that improve water quality and as indicators of aquatic health. In Nebraska and Wyoming, native mussel populations have declined sharply due to habitat modification, pollution, and reduced connectivity. Two species of particular concern are the Plain Pocketbook Lampsilis cardium, listed as Tier I at-risk in Nebraska, and the Fatmucket Lampsilis siliquoidea, a Tier II at-risk species. In response, state agencies …

Honeybee Colony Response To Probiotic Supplementation And Grazing Practices, Katya M. Busenitz

Department of Entomology: Dissertations, Theses, and Student Research

Honeybee health is a complicated issue. Studies were conducted to scale honeybee (Apis mellifera) health from the microbiome to the landscape. Colony health parameters were measured in response to probiotic administration. Colony capped brood production, colony summer weight gain, and Varroa mite incidence were measured. I found that applications of over-the-counter probiotics did not improve the measured parameters of honeybee health compared to a control group. Results suggest that probiotic application was not beneficial but positive benefits may depend on application method, brand, or strain of probiotics used. I also examined how colony health metrics responded to different …

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 …

Impacts Of Supplemental Fat In Finishing Diets On Digestibility, Performance, Carcass Outcomes, Meat Quality And Methane Production Of Feedlot Cattle, Anna Marie Kobza

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Rising costs and fluctuating availability of supplemental fats has led to increased interest in alternative fat sources or feed additives that might improve utilization of supplemental fat in feedlot diets. Two separate experiments were conducted to evaluate alternative strategies to overcome high fat prices. The first experiment was a metabolism study, conducted to evaluate digestion parameters of supplemental fat sources with or without LYSOFORTE Extend. The objectives of this experiment were to evaluate LYSOFORTE Extend in beef finishing diets containing a saturated fat source (tallow) and unsaturated fat source (corn oil). Duodenally and ruminally fistulated steers were fed diets containing …

Assessment Of Precision Rangeland Management Tools In The Nebraska Sandhills, Hannah K. Allen

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The objective of this thesis is to evaluate tools and management strategies that contribute to rangeland monitoring and livestock distribution in heterogeneous grassland systems of the Nebraska Sandhills. Chapter one reviews relevant literature related to precision livestock management, the Nebraska Sandhills, biomass estimation, and pyric herbivory. The second chapter evaluates the use of fractional green canopy cover (FGCC) derived from the Canopeo mobile application as a rapid method for estimating aboveground biomass in Sandhills rangelands. Biomass samples were collected across topographic positions in both early and late growing season, and relationships between FGCC and clipped biomass were assessed using generalized …

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 …

Factors Influencing Sex-Based Movement Patterns In The Banded Garden Spider, Argiope Trifasciata (Forskal, 1776), Brandon R. Marrone

School of Biological Sciences: Dissertations, Theses, and Student Research

Movement is a fundamental ecological process shaping how individuals acquire mates, secure resources, and navigate heterogeneous landscapes. In species with extreme sexual size dimorphism (eSSD), such as the orb‑weaving spider Argiope trifasciata, males and females are predicted to experience different movement pressures driven by their reproductive roles. This thesis examines how individual traits and environmental conditions jointly influence movement across both sexes. Across two field seasons, we used intensive mark–recapture methods to quantify natural movement patterns of males and females within mapped prairie plots. The first chapter tested long‑standing predictions gravity hypothesis, which posits that smaller males benefit from …

Perceived Barriers To Integrated Crop–Livestock Systems: Evidence From A Nebraska Producer Survey, Omid Tarashtwal

Department of Agricultural Economics: Dissertations, Theses, and Student Research

Integrated crop-livestock systems offer agronomic, economic, and environmental benefits, yet reintegration has been slow across the Northern Great Plains despite sustained interest. Existing research has documented barriers to transition conceptually, but quantitative evidence on which barriers producers perceive as most important and which producer and operation characteristics are associated with stronger barrier perceptions remains limited. This thesis addresses that gap using data from the 2023 Nebraska Agriculture Operator Survey.

The analysis focuses on 241 Nebraska producers, including 179 crop-only and 62 livestock-only operations. Seven models are estimated, combining ordered logit estimation for single-item barriers with linear regression for averaged barrier …

Vultures, Bryan M. Kluever, Lee A. Humberg, Scott C. Barras

Wildlife Damage Management Technical Series

Fact sheet about vultures including information about human--wildlife conflicts, the vulture roost, affects on livestock, structures, human health and safety, identification of damage, management methods, legal considerations, and economics. Also included is an overview of the species.

Evaluating Cow/Calf And Stocker Performance When Grazing Sudangrass With And Without Sunnhemp, Shelby L. Davis-Jenkins, Daren D. Redfearn, Mary E. Drewnoski

Nebraska Beef Cattle Reports

Summary with Implications

Sudangrass can provide high-quality summer forage, supporting cow/calf pairs and growing cattle. In this study, sudangrass or a sudangrass–sunnhemp mix was grazed over two years by cow/calf pairs and heavy stockers (~880 lb). There was no difference in carrying capacity between forage types. Sunnhemp inclusion had no effect on cow body condition or nursing calf gain. Cows maintained condition through peak lactation, and nursing calves gained 2.27 lb/day. Stockers gained 1.56 lb/day on sudangrass alone and 1.73 lb/day on the mix. However, the added seed cost of sunnhemp increased the cost of gain in year 1 and …

Effect Of Corn Harvest With A Chopping Head On Performance Of Cattle Grazing Corn Residue, Conner K. Biehler, Mary E. Drewnoski, Jim C. Macdonald

Nebraska Beef Cattle Reports

Summary with Implications

The effects of harvesting corn using a chopping vs a standard, non-chopping combine head on steer performance when grazing corn residue were evaluated. Steers were supplemented with dry distillers grains at 0.6% of initial body weight. The amount of corn residue mass and the quality of the husk did not differ between harvest methods. Steer gains were over twice as high in year 2 (2.10 lb/d) than year 1 (0.76 lb/d), potentially due to greater husk digestibility and milder winter conditions. Corn residue harvested with a standard combine head resulted in a slightly higher average daily gain …

Artificial Insemination Of Beef Heifers With Multi-Sire Semen, Dempster M. Christenson, Jordan M. Thomas, Daniel J. Kelly, Rick N. Funston

Nebraska Beef Cattle Reports

Summary with Implications

This study compared pregnancy rates of beef heifers artificially inseminated with multi-sire semen to single-sire semen. It was hypothesized pregnancy rates resulting from multi-sire semen would be increased compared to single-sire semen. Heifers were artificially inseminated with semen from one of three sires or semen from a combination of the same three sires. Pregnancy rates did not significantly differ. Paternity testing suggests sire parentage can be unequal when semen is mixed from multiple sires. In summary, similar pregnancy rates were observed using single-sire and multi-sire semen, but progeny may have unequal sire representation.

Supplementing Monensin And Rumen Undegradable Protein To Late-Gestation Heifers, Dempster M. Christenson, Rick N. Funston

Nebraska Beef Cattle Reports

Summary with Implications

This study evaluates the effects of supplementing late-gestation heifers with rumen-undegradable protein and monensin on weight gain, feed efficiency, and reproductive performance, and subsequent impact on progeny. We hypothesized that supplementation would enhance growth and feed efficiency, ultimately improving cow and calf performance. Previously synchronized artificially inseminated heifers were fed ad libitum hay for 89 d prior to calving. Feed was top dressed with chelated mineral with or without monensin, dried distillers’ grains, or dried distillers’ grains and monensin. Supplementation with rumen undegradable protein increased growth rate and decreased calving difficulty with no further effects on cow …

Effect Of Feeding Whole Soybeans, Roasted Soybeans, Or Distillers Grains In Silage-Based Growing Beef Diets, Melissa K. Bausch, Rebecca Mcdermott, Jim C. Macdonald, Pablo L. Loza, Galen E. Erickson

Nebraska Beef Cattle Reports

Summary with Implications

An individual feeding experiment was conducted to evaluate the effect of feeding raw whole soybeans (WSB), roasted whole (RSB) soybeans or distillers grains (MDGS) at three inclusions (7%, 14%, or 21% of diet dry matter) on growing performance, compared to a common control diet (0%) with urea. The greater inclusions of roasted soybeans or distillers grains increased gain and efficiency in growing cattle. Cattle fed the 21% inclusion of roasted soybeans were the most efficient, likely due to the protected protein increasing rumen undegradable protein content, and the additional energy from the higher levels of fat and …

Live Biomass Estimation With Canopeo In Rangeland Systems, Hannah K. Allen, Mitchell B. Stephenson, Daniel R. Uden

Nebraska Beef Cattle Reports

Summary with Implications

This project evaluated Canopeo, a free smartphone app that estimates fractional green canopy cover (FGCC), as a tool for monitoring aboveground biomass in Nebraska Sandhills rangelands. Live biomass was significantly higher in August than in June with some variability by year. FGCC showed a moderately strong relationship with current-year live biomass collected in either June or August. These results indicate that, in addition to producers’ field knowledge, Canopeo images taken with a smartphone or digital camera can offer a quick, visual estimate of forage conditions. This method may help reduce the need for labor intensive and destructive …

Effect Of An Accelerated Adaptation Protocol On Performance And Health Of Feedlot Steers Drenched With Lactipro, Rebecca L. Mcdermott, Samuel E. Loy, Isaque F. Vicci, Mark Corrigan, Braden C. Troyer, Galen E. Erickson, Jim C. Macdonald

Nebraska Beef Cattle Reports

Summary with Implications

A finishing study evaluated the effects of an accelerated adaptation protocol in conjunction with Lactipro on performance and health of steers. Five adaptation programs were evaluated with steers adapted to a finishing diet in 21, 14, 7, or 0 days. An additional accelerated adaptation program provided intensive feed delivery with 0-d adaptation. Cattle assigned to the 21-d and 0-d adaptations gained faster and consequently had greater HCW compared to the 7-d and 14-d adaptation, resulting in a quadratic response for ADG and HCW. The 0-d adaptation with intensive feed delivery had similar ADG and HCW compared to …

Energy Value Of High-Moisture Corn In Feedlot Cattle Diets Derived Through Meta-Analysis, Alfredo Dicostanzo

Nebraska Beef Cattle Reports

Summary with Implications

Cattle feeders or their nutritionists who rely on high-moisture corn (HMC) use a standard adjustment to energy content of the diet based on observation or previous research reports. Because moisture content of HMC is the result of many field and harvest factors, a common adjustment to the energy value of HMC applied to all conditions may not be appropriate. The hypothesis that moisture content of HMC determines its energy concentration was tested. Through a meta-analysis, it was determined that feed intake was depressed while energy content of HMC increased at greater moisture content. A simple method to …