Agriculture Commons^™

The Invisible Meat Microcosmos - Investigations Of Processed Meats' Specific Spoilage Organisms, Rebecca Furbeck

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

As humankind grows in population, so will our need to compete against bacterial populations which spoil foodstuffs before we are able to consume them. This dissertation aims to identify the bacterial communities responsible for meat spoilage, and the mechanisms that govern the behaviors of these organisms. The literature review summarizes the state of knowledge regarding factors that influence meat microbiome composition, and how analytical methods can influence research outcomes. Study 1 aimed to identify the impact of additional ingredients and processing steps on the microbial ecology of processed turkey products. The main specific spoilage organisms (SSOs) belonged to the orders …

Molecular Mechanisms Underlying Aberrant Circulating Steroid Hormones In Gnrhr-Ii Knockdown Boars And Their Control Littermates, Dorothy Elsken

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

Swine are the only livestock species that produce a functional protein for both GnRH-II and its receptor (GnRHR-II). Our laboratory reported that the interaction between GnRH-II and GnRHR-II facilitates testosterone production, independent of LH stimulation. To further examine GnRHR-II function, we developed a swine line with 70% reduced GnRHR-II mRNA levels (GnRHR-II KD) compared to control littermates. Mass spectrometry analysis of serum revealed that circulating levels of gonadal steroids were reduced in mature transgenic vs. control boars. Paradoxically, evaluation of testicular tissue indicated no difference between lines for gonadal steroid hormone levels. To address a potential cause for this discrepancy, …

Variance Component Estimates For Growth Traits In Beef Cattle Using Selected Variants From Imputed Low-Pass Sequence Data, Chad A. Russell

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

A beef cattle population (n=2,343) was used to assess the impact of variants identified from imputed low-pass sequence (LPS) on the estimation of variance components and genetic parameters of birth weight (BWT) and post weaning gain (PWG). Variants were selected based on functional impact and were partitioned into four groups (Low, Modifier, Moderate, High) based on predicted functional consequences and re-partitioned based on consequence of mutation, such as missense and untranslated region variants, into six groups (G1-G6). Each subset was used to construct a genomic relationship matrix (GRM) for univariate animal models. Multiple analyses were conducted to compare the proportion …

Environmental Determination Of Gastrointestinal Parasitism In Katahdin Sheep, Brian Arisman

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

Gastrointestinal nematodes (GIN) negatively affect the performance and wellbeing of sheep and are difficult to control due to anthelmintic resistance. Producers are therefore choosing breeds naturally resistant to GIN infection, such as the Katahdin. Katahdin are raised in various climates and management systems in the U.S., and those environmental factors can be combined into eco-management clusters. We hypothesized that GIN challenge varies predictably based on the characteristics of these clusters. Katahdin producers from across the U.S. were surveyed for management information. Body weights (BW), fecal egg counts (FEC) and FAMACHA scores (FAM) were collected on 3,527 Katahdin lambs around 90 …

Impacts Of Feeding Biochar To Beef Cattle On Greenhouse Gas Emissions And Performance And Characterizing Yearling Steers Grazing Smooth Bromegrass Pasture Using Gps, Holly Heil

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

As global warming continues to rise, the pressure and growing demand for sustainable animal production is increasing. Livestock naturally produce greenhouse gas emissions through enteric fermentation. Dietary manipulation strategies have been sought out to decrease emissions in ruminants using feed additives.

Two independent finishing feedlot experiments evaluated two types of biochar and its effects on animal performance, carcass characteristics and greenhouse gas emissions. Experiment 1 utilized pistachio shell biochar and experiment 2 utilized biochar sourced from ponderosa pine wood waste, both types included at 1% of the diet DM. The addition of biochar to the diet did not impact animal …

Evaluation Of Nutritional Factors Affecting Sow Reproductive Longevity, J'Nan E. Wittler

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

Sow reproductive longevity is an important trait for swine operations from a production and economic standpoint. Previous research has shown that a sow needs to produce 3 litters before she covers the costs associated with introducing her to the operation. A literature review of research conducted related to sow longevity is discussed in Chapter 1. Chapters 2 and 3 present data from the University of Nebraska – Lincoln’s long-term sow longevity research. The research looks at the effects of energy restriction with soy hulls during gilt development on sow reproductive longevity through 4 parities. Chapter 2 presents data from replications …

Identifying Early-Life Behavior To Predict Mothering Ability In Swine Utilizing Nutrack System, Savannah Millburn

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

Early recognition of indicator traits for swine reproduction and longevity supports economical selection decision making. Gilt activity is a key variable impacting a sow’s herd life and productivity. The purpose of this study was to examine early- life behaviors contributing to farrowing traits including gestation length (GL), number born alive (NBA), number weaned (NW), and herd life (HL). Herd life was a binary trait representing if a gilt was culled after one parity. Beginning at approximately 20 weeks of age, video recordings were taken on 480 gilts for 7 consecutive days and processed using the NUtrack system. Activity traits include …

Using Strategic Supplementation To Enhance Cow/Calf Productivity In Summer Calving Herds In The Nebraska Sandhills, Nicole M. Woita

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

Young range beef cows consuming low-quality forage may result in an imbalance of energy and metabolizable protein, which can negatively affect the nutrient status of the cow and reproductive performance. In a 2-yr study conducted at Gudmundsen Sandhills Laboratory near Whitman, NE, 2- and 3-yr-old May-calving range cows (n = 181) grazing native range were individually supplemented daily with one of four supplements: 1) mineral with a target intake of 113 g/d (MIN), 2) MIN with 200 mg per head of Rumensin to with a target intake of 113 g/d (RUM), 3) MIN with a 226 g/d of high RUP …

Evaluation Of The Feeding Value Of Proso Millet In Growing-Finishing Diets For Pigs And Effects Of Feed Ingredients And Medium-Chain Fatty Acids On Porcine Reproductive And Respiratory Syndrome Virus (Prrsv) Survivability, Khang Nguyen

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

The objective of the project were to: 1) evaluate the feeding value of proso millet as a potential substitute for corn in corn-soybean meal-based diets for pigs; and 2) investigate the relationship between feed ingredients and virus survivability, followed by examining feed additive candidates that could mitigate the risk of transmission of viral pathogens.

In Exp. 1, 36 barrows were fed 1 of 4 dietary treatments, including: Diet 1, corn-soybean meal-based (control), and Diets 2, 3, and 4 had proso millet replacing 33%, 67%, and 100% of corn in the control diet, respectively. During Phase 3, pigs consuming the proso …

Impact Of Increasing Level Of Milk Production On Cow And Calf Behavior And Performance In The Nebraska Sandhills, Selby Boerman

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

Selection for increased milk production across the United States has resulted in variable cow and calf production responses. Better understanding of calf nursing and grazing behaviors may provide opportunities to help estimate how milk and grazed forage intake influence variability in calf performance. In a 2-yr study, cow-calf pairs (n = 65) were equipped with neck collars containing global positioning system (GPS) units to validate the efficacy of high-frequency GPS data to accurately identify calf nursing events and grazing behavior. Data were collected during 3-wk tracking periods during early lactation (calf age 65.4 ± 10.0 d; EARLY) and late lactation …

The Impact Of Steam-Flaked Rye Replacing Steam-Flaked Corn On Performance And Carcass Characteristics Of Yearling Steers And The Effect Of Exogenous Megasphaera Elsdenii Administration Techniques On Ruminal Fermentation And Blood Parameters In An Acidosis Challenge Model, Samantha K. Wagner

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

A feedlot study was conducted to evaluate the effects of replacing steam-flaked corn (SFC) with steam-flaked rye (SFR) in the diets of yearling steers (Exp. 1). A separate study was conducted to evaluate the effects of three different administration techniques of Megasphaera elsdenii NCIMB 41125 on rumen fermentation and blood parameters in an acidosis challenge model (Exp. 2). In Exp. 1, SFC was replaced with SFR to create four different treatments, each differing in the ratio of SFC:SFR. The four treatments were 0:100, 25:75, 50:50, and 100:0 SFR:SFC (as a percentage of the grain inclusion). Increasing inclusions of SFR resulted …

Targeting Inflammation In Heat-Stressed Wethers Improves Growth And Efficiency And Alters Body Composition; A Brief Exploration And Application Of Extension Principles, Micah Most

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

The objective of our first study was to determine how administering anti-inflammatory dexamethasone and ω-3 polyunsaturated fatty acid (PUFA)-rich fish oil affects growth efficiency and body composition in heat-stressed finishing lambs. Commercial wethers were randomly assigned to be fed under heat stress (35°-40℃) or thermoneutral (19℃, n = 10) conditions for 30 d, and controls were pair-fed to eliminate differential feed intake. Heat-stressed wethers were randomly assigned to receive clinical-dose dexamethasone IM injections every 72 h, twice daily fish oil capsule oral boluses, or placebos. Heat stress decreased (P < 0.05) growth and efficiency, but dexamethasone and fish oil supplementation recovered these performance measures. Heat stress also decreased (P < 0.05) predictive body composition metrics that were at least partially improved by administration of dexamethasone and fish oil. Proximate analyses of muscles showed that heat stress decreased (P < 0.05) percentage of protein and increased (P < 0.05) percentage of intramuscular fat, neither of which was improved by dexamethasone or fish oil. Immunohistochemistry revealed that heat stress decreased (P < 0.05) myoblast differentiation and muscle fiber size, but anti-inflammatory supplementation recovered differentiation only. Plasma IGF-1 concentrations were not different among groups throughout the study. These findings demonstrate how heat stress-induced inflammation contributes to impaired growth, efficiency, and body composition observed in heat-stressed feeder lambs. However, targeting inflammation with dexamethasone or fish oil recovers many of these deficits.

The Cooperative Extension Service, …

The Impact Of Plant Cell Wall Lignin On Energy Utilization In Lactating Jersey Cows., Jason Stypinski

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

Fiber from forages comprises a significant proportion of dairy cattle rations and by extension, it contributes largely to the energy concentration of the diet. While the proportion of fiber in the diet is important, the composition of fiber is probably more important as the different constituents of this fraction vary in their contributions to the nutritive value of the feed. Lignin has been described as an important factor limiting the digestion of NDF, reducing intake, and compromising milk production. Although lignin’s effects on these responses have been well characterized, the literature lacks data on the use of indirect calorimetry to …

Annotating Gene Expression And Regulatory Elements In Tissues From Healthy Thoroughbred Horses And Identifying Candidate Mutations Associated With Perosomus Elumbis In An Angus Calf, Alexa Barber

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

Genome annotation has a direct impact on the success of genomic studies. Transcriptome analyses and chromatin immunoprecipitation and sequencing (ChIP-seq) have been used to functionally annotate genomes. These methods can identify protein-coding genes, non-coding transcripts, and cis-regulatory elements across the genome. The primary objective of the first study was to functionally annotate the equine genome through the assessment of nine tissues: adipose, brain, heart, lamina, liver, lung, skeletal, muscle, testis, and ovary. In the first project, 150 bp, paired-end RNA sequencing (RNA-seq) libraries were generated in stallion tissues and compared to previously generated mare RNA-seq libraries to quantify variation in …

Investigating Bacterial Community Composition And Antimicrobial Resistance Genes In Beef Cattle, Arena See

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

While antibiotics have been critical over the last decade for curbing infectious diseases, they have contributed to the rise of antimicrobial resistance (AMR). Infections resulting from antimicrobial-resistant pathogens are correlated with severe morbidity, mortality, and healthcare costs. With the increasing concerns regarding AMR and its emergence, it is paramount to understand not only the effects of antibiotics on microbial community and diversity, but also to develop a novel tool that gives us a better understanding of the spread and functional traits of AMR genes.

To this end, rumen, fecal, and pen surface samples were collected from 72 animals at US …