Life Sciences Commons^™

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 …

The Role Of Gnrh-Ii And Its Receptor In Testicular Function, Amy Desaulniers

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

The second mammalian isoform of GnRH (GnRH-II) has been linked to regulation of cell proliferation, feed intake, and the interaction between energy balance and reproductive behavior. In contrast to the native form of GnRH (GnRH-I), GnRH-II is an inefficient modulator of gonadotropin secretion. Unlike many species, a functional receptor (GnRHR-II) specific to this ligand has been discovered in the pig that may be directly involved in testosterone production. Therefore, our objective was to identify the role of GnRH-II and its receptor in testicular function. First, there was 6-fold more GnRHR-II protein in the testis than anterior pituitary gland of boars. …

Evaluation Of Collection Method And Diet Effects On Apparent Digestibility And Energy Values Of Swine Diets, Yanshuo Li

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

Two experiments were conducted to investigate the effects of collection method and diet on estimating digestibility values. In Exp. 1, 24 barrows were fed either a corn-soybean meal diet (CSBM) or CSBM with 20% dried distillers grains with solubles (DDGS). Fecal collections were based on exact timing (Day collection) or marker-to-marker collection (MM) methods during a 4-d period. Diets contained 0.5% of titanium dioxide (TiO₂) for estimating digestibility using the index method. In Exp. 2, the effects of collection method and basal diet on determination of DDGS digestibility were studied using 24 barrows. Diets were CSBM (basal 1), …

Use Of Alkaline Treated Crop Residues As Partial Grain Replacements For Finishing Cattle, Adam L. Shreck

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

Recently, corn has become expensive and this has led to high feed costs and decreased profitability. High priced corn has allowed for the consideration of other ingredients as replacements to reduce diet cost. In much of the Corn Belt, supplies of wet or modified distillers grains and crop residues are abundant. These ingredients were investigated as corn replacements. Studies were conducted to identify methods for treating crop residues to improve digestibility and value in finishing diets based on corn grain and corn wet distillers grain with solubles (WDGS). Digestibility and value of crop residues were improved by mild chemical treatment. …

Nutrient, Tenderness, And Strip Loin Differences Of Beef From Cattle Due To Mutation Of The Myostatin Gene, Michelle Elaine Semler

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

The objectives of this study was to determine tenderness, nutrient, and musculature differences of loins from cattle with variation of myostatin gene. Steers (n = 21, 22, and 16) and heifers (n = 19, 20, and 20) were genotyped as homozygous (MM; active myostatin gene), heterozygous (Mm; partially recessive myostatin) or homozygous (mm; recessive inactive myostatin), respectively. At 3 d post mortem Longissimus dorsi (LD) and Semitendinosus (ST) were collected. Loins were cut into 2.5 cm thick steaks evaluated for: total number steaks, total number vein steaks, total number non-vein steaks, and individual steak weight. Nutrient analysis steaks were cut …

Effect Of Residue Removal On Subsequent Year Quality And Quantity Of Corn Residue And Cattle Performance While Grazing Corn Residue At Different Stocking Rates, Adam L. Mcgee

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

Two studies evaluated the impact of residue removal; study 1, grazed in the fall or spring, study 2, removed by grazing at two stocking rates, light (LG), heavy (HG), or baled(B). There were no differences in pre-grazing treatments for digestibility, CP, NDF, plant fraction as a percent of residue and kg/25.5 kg of grain. Digestibility was highest in husk and lowest in stem. CP was greatest in leaf blade and lowest in husk. NDF was highest in the leaf sheath and lowest in the cob while stem is the greatest percentage of the plant and husk the smallest. The fractions …

Effects Of Drying Distillers Grains Plus Solubles On Feedlot Cattle Performance And Nutrient Digestibility, Brandon L. Nuttelman

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

All dry milling ethanol plants produce wet distillers grains (WDG) and distillers solubles (DS). Depending on the plant, WDG and DS will be combined to produce wet distillers grains plus solubles (WDGS). Some plants will partially dry WDGS and market modified distillers grains plus solubles (MDGS), or other plants will completely dry WDGS to produce dried distillers grains plus solubles (DDGS). These products have been shown to contain greater feeding values than the corn it replaces in finishing diets. However, as drying intensity of distillers grains plus solubles (DGS) increases, the feeding value relative to corn decreases. Three finishing experiments …

Production Management Factors Affecting Inherent Beef Flavor: The Role Of Post-Weaning Forage, Energy Supplementation, Finishing Diets, And Aging Periods, Kimberly A. Varnold

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

Projects were conducted to determine effects of diet and aging periods on inherent beef flavor characteristics by relating biochemical constituents of meat, consumer acceptability, and lexicon flavor notes of two different muscles. Prediction equations were also created. Warm-season grasses caused increased concentrations of moisture, heme iron, and zinc in L. dorsi steaks. Aging 28 d instead of 7 d caused increased pH, carbohydrate, and heme and non-heme iron concentrations in B. femoris steaks. Warm-season grasses caused decreased concentrations in a majority of fatty acids, specifically when supplementation was not provided. Few differences were observed with cool-season grasses. Provision of wet …

Maternal Obesity Alters Fetal Development Due To Impaired Placental Function And Has Lasting Effects On Adult Offspring, Kristin Ann Norwood

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

Obesity is an epidemic in many developed nations and maternal obesity can result in developmental alterations in offspring that have long-lasting effects. Two experiments were conducted to determine the impact of maternal obesity on placental development and early embryonic growth and muscle development. Experiment one utilized obese Lethal Yellow (LY) and normal weight C57BL/6 (B6) dams to assess how maternal obesity alters skeletal muscle development in mid-gestational embryos. Embryos from LY dams exhibited decreased embryo and placental weights as well as an increase in the myogenic marker desmin. Furthermore, the adipogenic marker PPARG expression was predominately localized to the neural …

Supplementing Distillers Grains In A Yearling System As A Forage Replacement Tool With Bunk Or Ground Feeding, And Impact Of Winter Supplementation Level On Finishing Performance And Profit, Kari L. Gillespie

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

The benefit of adding weight to cattle prior to entering the finishing phase through a forage-based backgrounding system has become more important with increased corn price. Further, as competition for available forage increases, the value of replacing grazed forage with a supplement such as distillers grains, also increases.

A 2-year beef systems study evaluated optimal supplementation time of distillers grains and summer forage savings with distillers supplementation. High winter level supplementation of distillers grains increased winter ADG, decreased summer ADG, and increased final live weights and HCW compared to cattle supplemented at a low supplement level designed to only meet …

Selection Objective For Improving Efficiency Of Beef Cattle, Jose A. Barron Lopez

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

Simulation studies based on 1000 cows were used to evaluate biological and economic efficiency of level of milk production and two production systems, and to estimate economic values for a breeding objective and selection indexes for beef cattle. Published data were used as information for this study. Average 10-yr prices, reproduction, survival, growth, carcass characteristics, and genetic parameters from journal papers were used in the simulations. In the first study, low (L), medium (M), and high (H) milk production cows, and calf-fed and yearling systems, were analyzed. Biological and economic efficiencies were estimated for weaning and slaughter endpoints. In the …