Animal Sciences Commons^™

Subjective Measures Of Temperament In Beef Heifers Are Reliable Indicators Of Physiological Stress And Indicate Acclimation To Repeated Handling, Jamie Parham

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

Associations between excitable temperament and many economically relevant traits have been established. In being heritable, temperament can be augmented through selection. Current methods to evaluate temperament in a production setting include numerous subjective and objective measurements, which some producers may find cumbersome to navigate. Those who utilize these methods may not do so efficiently if selection criteria are not indicative of an animal's response to stress, or initial evaluations are not strong indicators of future temperament. The objectives of this research were to develop a procedure for evaluation of calf behavior, indicative of physiological stress, and then determine whether stress …

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 ( …

Comparison Of Traditional And Alternative Ingredients On Meat Curing Reactions Using A Model System, Faith Rasmussen

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

Consumer’s negative perception of “chemical-sounding” ingredients has increased the use of alternative ingredients. The objective of this study was to determine the effect traditional (sodium nitrite with or without sodium erythorbate) or alternative (celery juice powder with or without acerola cherry powder) curing systems with different ingoing concentrations of sodium nitrite using model meat solutions. Curing systems with reducing agents developed the most cured meat pigment (p < 0.001). Using more than 50 ppm of nitrite did not further increase cured meat pigment (p < 0.001). Curing systems with reducing agents and 50 ppm or greater nitrite had the least residual nitrite (p < 0.001). Alternative curing systems had the most residual sulfhydryl groups when formulated with 100 ppm or more nitrite (p < 0.001). Treatments with reducing agents had greater residual reducing capacity than treatments without reducing agents (p < 0.001). Both alternative and traditional curing systems develop similar cured meat pigment but differences in the nitrosation of cysteine exist.

Advisor: Gary A. Sullivan

Dissection Of Qtl On Host Chromosome 12 Uncovers Candidate Gene And Missense Polymorphism Associated With Porcine Circovirus 2 Susceptibility, Lianna R. Walker

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

Porcine circovirus 2 (PCV2) is a small single stranded DNA virus responsible for a group of detrimental diseases referred to as Porcine Circovirus Associated Diseases (PCVAD). Observed variation in incidence and severity of PCVAD between pigs suggests a host genetic role in facilitating PCV2 pathogenesis. This study builds on prior research by Engle et al. (2014), who performed a large-scale genome-wide association study of 974 crossbred pigs experimentally infected with a PCV2b isolate and provided evidence of a host genetic role in PCV2 viremia, immune response, and growth. Two major Quantitative Trait Loci (QTL) were identified for viral load located …

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 …

Energy Value Of De-Oiled Distillers Grains Plus Solubles In Beef Cattle Diets, Meredith L. Bremer

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

Ethanol plants are centrifuging off oil from the thin stillage stream as it has added market value currently. The impact of oil removal on cattle performance has been minimally researched. Thus four trials, one growing, one digestion, and two feedlot, were designed to determine the energy and feeding value of de-oiled distillers grains in beef cattle diets.

In growing cattle diets, diet concentration of modified distillers grains plus solubles (MDGS) impacted cattle performance more than oil content. Ending BW, ADG, and G:F did not differ between cattle fed de-oiled or full fat MDGS, however cattle fed de-oiled MDGS had lower …

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 …

Genome-Wide Analysis Of The Variation In Host Genetics In Response To Experimental Challenges With Porcine Circovirus 2b, Taylor B. Engle

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

Porcine circovirus is the primary causative agent responsible for inducing a group of associated diseases known as porcine circovirus associated diseases (PCVAD), which can have detrimental effects on production efficiency as well as lead to mortality. The variation in host genetics plays a role in the ability to initiate an effective immune response. The objective of this research was to identify major genetic variants and genes that influence immune response and PCVAD susceptibility. Commercial crossbred pigs (n=974) were experimentally infected with a PCV2b strain to analyze genetic sources of variation in PCVAD susceptibility. The strain used for experimental infection was …

Transcriptional Regulation Of The Porcine Gnrh Receptor Gene By Glucocorticoids, Chanho Lee

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

Binding of GnRH to its receptor (GnRHR) stimulates the synthesis and secretion of the gonadotropins, as well as up-regulation of GnRHR. Thus, the interaction between GnRH and GnRHR represents a central point for regulation of reproduction. Glucocorticoids alter reproduction by reducing GnRH responsiveness of gonadotropes within the anterior pituitary gland, potentially via transcriptional regulation of the GnRHR gene. Investigation into this mechanism, however, revealed that the murine GnRHR gene was stimulated by glucocorticoids. To determine the effect of glucocorticoids on porcine GnRHR gene expression, gonadotrope-derived αT3-1 cells were transiently transfected with a vector containing 5118 bp of 5’ flanking sequence …