105 results
Search Results
Now showing 1 - 10 of 105
Item The Impact of Management Decisions and their Effect on Reproductive Performance of Beef Cattle(North Dakota State University, 2014) Schook, Mellissa ReneeTwo experiments were conducted to evaluate two management decisions made by beef cattle producers and their impacts on reproduction. In experiment 1, growth, attainment of puberty, and pregnancy rates were evaluated in crossbred heifers originating from two different breeding systems: 1) cows only exposed to natural service herd bulls (NS), or 2) cows exposed to ovulation synchronization and fixed-time AI followed by natural-service bulls (TAI, fixed-time artificial insemination). Artificial insemination did not influence growth rate during the development phase, attainment of puberty, or pregnancy rates in heifer progeny. In experiment 2, pregnancy attainment and calving distribution of beef females administered a control saline dose, killed virus, or modified-live pre-breeding vaccine per label recommendations were compared. No differences in pregnancy attainment were observed among the 3 time points measured, d 28, 56, and 90 as well as no differences seen among the calving distribution.Item Biological Abnormalities in the Ruminant Small Intestine and Its Relationship to Carbohydrate Assimilation(North Dakota State University, 2019) Trotta, RonaldSeveral biological abnormalities exist between the ruminant and nonruminant small intestine and influences carbohydrate assimilation. Two experiments were conducted to identify potential mechanisms to improve carbohydrate utilization in cattle. Experiment 1 evaluated the effects of duodenal starch infusions with casein or glutamic acid on post-ruminal carbohydrase activities. Experiment 2 evaluated the effects of dietary fructose on visceral organ development and expression of nutrient transporters and digestive enzymes involved in carbohydrate assimilation. In experiment 1, the results suggest that small intestinal starch digestion may be improved in cattle with increased small intestinal flow of casein through increases in post-ruminal carbohydrase activities. In experiment 2, dietary fructose supply influenced nutrient utilization, visceral organ growth, and digestive enzyme mRNA expression and activity in neonatal calves.Item Estimating the Impacts of Litter Size and Non-Additive Genetic Effects on Ewe Longevity and Stayability in a U.S. Western Extensive Range Production System(North Dakota State University, 2021) Oribamise, Babatunde VictorNon-additive genetic effects are usually ignored in animal breeding programs due to data structure, computational limitations, and over-parameterization of the models. Non-additive genetic effects play an important role in the expression of complex traits in livestock species, such as longevity and stayability. Components of genetic variance for additive and non-additive genetic effects were estimated for longevity and stayability in U.S. Western ewes using pedigree relationship matrices. Litter size were also investigated for direct and maternal effects. For longevity, a larger proportion of phenotypic variance was explained by non-additive genetic effects than by additive effects for model A+D, indicating that including dominance genetic effects are important. Results suggest that inclusion of non-additive genetic effects in animal models is possible in estimating longevity and stayability and will improve selection accuracy and reduce overestimation of additive genetic effects.Item Ancestral Breed Grouping for Improving Animal Modeling in Admixed Populations and Its Use in Leptin (Genetic and Hormone) Association Studies with Performance Traits in Commercial Beef Cow Herd(North Dakota State University, 2021) Bhowmik, NayanThe first study investigated American Aberdeen (AD) cattle's genetic structure and its genetic relationships with five American taurine beef breeds and the genetic population structure of a related admixed cattle herd for improved statistical modeling. The last two studies investigated the role of leptin (LEP) c.73C>T polymorphism, leptin diplotype (LEPD), and leptin hormone (LEPH) concentration on reproductive, growth, size, feeding, and carcass ultrasound traits in beef cows and heifers. High levels of polymorphism were observed in admixed, Red Angus, and Gelbvieh (GV) populations. The lowest level of polymorphism was found in AD followed by undetermined parentage. Pairwise fixation index displayed the largest genetic differentiation between AD and GV, Simmental, and Shorthorn breeds. Even though founder animals originated from the Angus breed, the AD breed exhibited unique genomic characteristics. Mixed animal models with or without pedigree that included the primary ancestral breed group (ABG) for admixed individuals developed from diversity analyses performed better than models without the ABG. With these improved models, novel relationships between LEP genotype and number of follicles and ovary size were identified. Similar relationships of the LEP genotype in multiple growth and weight traits that have been published before have been confirmed. However, reverse relationships were observed for feed efficiency. The LEPD showed associations for feed efficiency, weight traits, and body size traits. Novel relationships between LEPH categories (high vs. low) were reported on two feeding behavior traits, including number of meals per day and feed intake per meal. However, no relationship was observed between LEP genotype and plasma LEPH concentration in this population. Literature indicates the increased productivity of the T allele for growth and carcass attributes, so it was expected that the same increased productivity would be found for reproductive traits. Therefore, the T allele of LEP c.73C>T marker could be used as a valuable marker for selecting for improved growth, body size, and reproductive performance in commercial beef heifers. Also, circulatory LEPH before the breeding season may serve as a predictor for feeding behavior, body size, and reproductive traits. Even so, not all comparisons could be statistically proven; therefore, additional investigations may be warranted.Item Effects of Linseed Meal on Growth and Reproductive Performance in Ruminants(North Dakota State University, 2011) Ilse, Breanne RoseLinseed meal (LSM) was fed to ovariectomized ewes exposed to estradiol 17-ß (E2) implants over time, and LSM was supplemented to beef cows during late gestation and early lactation to evaluate the estrogenic potential of the phytoestrogen secoisolariciresinol diglycoside (SDG) found in LSM. Forty-eight ovariectomized ewes were fed a diet containing 12.5% LSM for 0, 1, 7, or 14 d and implanted with estradiol-17ß (E2) for 0, 6, or 24 h before tissue collection. Uterine cellular proliferation, vascularity, and the expression of the angiogenic factors and their receptors were recorded. There was an interaction of LSM and E2 on uterine mass (P = 0.05). At 24 h of E2 exposure, proliferation was reduced (P < 0.001) when ewes were fed for 14 d compared to being fed 0 or 1 days. There was a LSM x E2 interaction (P ≤ 0.03) on VEGF receptor-2 (KDR) and hasicfihrohlast growth factor receptor (FGFR2) decreasing by 24 h E2 exposure. Exposure of LSM and E2 may impact the estrogenic response of sensitive tissue. Two studies were conducted to examine the effects of supplementing beef cows with LSM during late gestation or early lactation on calf growth and development. In Experiment 1, multiparous cows received either LSM or a control (CON) supplement (approximately 10% diet dry matter) for the last 60 d of gestation. Offspring weights, ADG, heifer age at puberty, conception percentage and steer carcass characteristics were recorded. In Experiment 2, multiparous cows received LSM or CON supplements (approximately 10% diet dry matter) during the first 60 d of lactation, and only heifer calf development performance was observed and recorded. Heifer calf weight, average daily gain, and attainment of puberty were assessed. For both experiments, birth weight, weaning weight and ADG were not affected (P > 0.31) by LSM supplementation. While final body weights were heavier (P = 0.04) for steer calves in Experiment 1, there was no effect (P = 0.09) of supplementation on carcass characteristics. In Experiment 1 and 2, attainment of puberty in heifer calves was not influenced (P > 0.58) by supplement type. Linseed meal supplementation during late gestation or early lactation does not appear to have a negative impact on calf growth, onset of puberty in heifer calves, or steer carcass quality, implicating that it may make a good supplement choice in cattle.Item An Evaluation of Feeding Hempseed Cake in Finishing Cattle Diets(North Dakota State University, 2022) Winders, ThomasUnderstanding the potential of hempseed cake to be used as a livestock feedstuff is important for both industrial hemp and beef producers. Experiment 1 evaluated the effects of hempseed cake (HEMP) on growth performance, feeding behavior, plasma metabolite concentrations across time, and carcass characteristics when fed in finishing diets to heifers in comparison to dried corn distillers grains plus solubles (DDGS). Experiment 2 investigated the effects of HEMP on diet ruminal fermentation parameters, total tract digestibility, nutrient flow, and nitrogen balance in finishing steers in comparison to DDGS and a control (CON) diet containing no byproduct. Experiment 3 explored the effects of hempseed cake on immune parameters in response to an endotoxin (lipopolysaccharide) challenge in finishing steers in comparison to DDGS and CON. In experiment 1, the HEMP diet reduced heifer growth performance and hot carcass weight while not influencing dry matter intake, feeding behavior, or other carcass characteristics. Plasma urea nitrogen (PUN) was greater for heifers fed the HEMP diet, and glucose and total amino acid concentrations were not influence by treatment. In experiment 2, ruminal ammonia and total VFA concentrations were greatest for steers fed the HEMP diet. Furthermore, organic matter (OM) intake tended to be greater, OM total tract apparent digestibility was reduced, and N digestibility was greatest for steers fed the HEMP diet, and site of digestion was influenced by treatment. Nitrogen retention was greatest in steers fed the HEMP diet, suggesting treatment influence on N metabolism. In experiment 3, there was a treatment by hour interaction for PUN, and plasma glucose and NEFA were not influenced by treatment. Plasma IL-1α, IL-36RA, and TNF-α were lowest in steers fed the HEMP diet, and all other cytokines and total amino acid plasma concentrations were not influenced by treatment. Hempseed cake negatively influences growth performance in large part because of reduced total tract apparent OM digestibility, while N total tract apparent digestibility and N retention are improved and immune response is influenced, so further understanding of these outcomes is needed to explore implications of feeding hempseed cake to finishing cattle.Item Management Considerations for Successful Technology Implementation in Beef Production Systems(North Dakota State University, 2015) Black, Danielle NicoleTwo experiments were conducted to evaluate management strategies that foster successful implementation of technology in beef production systems. In experiment 1, cow reproductive performance, BW, and serum concentrations of NEFA in cows and their calves were evaluated in response to moving cow-calf pairs from summer pastures into confinement feeding for a 10 d period of estrus synchronization and breeding. Reproductive performance was not impacted but calf BW were reduced in confined calves. In experiment 2, effects of moderate and aggressive implant strategies were evaluated in steers with varying genetic potential (GP) for gain and marbling. Steers with greater GP had greater intramuscular fat percentage before consuming high concentrate diets, and improved carcass marbling scores and quality grade compared with low genetic potential steers. Carcass marbling in steers of greater GP for marbling tended to be more sensitive to implant strategy than that of steers with lesser GP.Item Disseminating Agriculture Information using the BBQ Boot Camp Model(North Dakota State University, 2017) Germolus, Austen JohnThe BBQ Boot Camp program was designed to educate consumers about agriculture production and sustainability, while teaching outdoor cooking methods with meat as the focus. Through the BBQ Boot Camp model, consumer impact was analyzed using a pre- and post-program test. The test questions focused on outdoor cooking, agriculture practices, and food safety issues. Data were collected from 3,112 attendees from 31 BBQ Boot Camps in 2009–2013. Data were analyzed using the MIXED procedure in SAS with fixed effects of year, time, age, sex, and city size (1=population>15k; 2=population between 2.5k-15k; and 3=population<2.5k) and all two-way interactions were tested and removed from the model if P>0.1. Consumer demographics included men and women representing five age categories (18-29, 30-39, 40-49, 50-59, and 60+). Data collected provided a unique opportunity to observe factors influencing consumer purchase decisions and the ability to evaluate the effectiveness of this form of extension programming.Item Factors Affecting Testicular Growth and Development in the Beef Bull(North Dakota State University, 2019) Negrin-Pereira, NicolásAt present no single parameter can predict potential daily sperm production (DSP) in bulls. Sertoli cells (SC) are responsible for nourishing and providing physical support to germ cells (GC) throughout spermatogenesis. The size of the SC population established before puberty is one of the major factors determining DSP in the bull. Fine needle aspiration (FNA) is a technique used for diagnostic purposes in many species but its application to determine the size of the SC population remains unexplored. Our objectives were to compare two stains (immunohistochemistry vs. conventional HE) and three techniques to determine SC density in neonatal and prepubertal bulls [22G FNA (SMEAR), 14G needle with vacuum (CORE) and tissue section (HIS)], and the effects of three different interventions on testicular growth, development and cytology in neonates, pre and peripubertal bulls: corn supplementation during mid to late gestation of dams, the age of the dam and the administration of vitamin A. The significant correlation observed between GC and SC counts in neonatal and prepubertal bulls, highlighted the relationship between both cell populations established in the early gonad. Although no significant correlation existed between techniques for SC density, the significant relationship established between SC counts and GATA4+ cell density implies the process can be automated. Corn supplementation to multiparous dams during mid to late gestation did not have any effect on testicular gross parameters and cytology in neonatal bulls coincident with the lack of differences in fetal growth between treatments. No significant differences in scrotal circumference, testicular weight or cytology existed between prepubertal bulls from primiparous heifers or adult multiparous cows. Nevertheless, bulls from heifers had lower bodyweights at 194 days of age compared with bulls from cows. The administration of vitamin A to peripubertal bulls had no effect on scrotal circumference, testicular weight or cytology. Nevertheless, epididymis in treated bulls were significantly heavier than non-treated animals. The data generated in the present experiments highlights the need for more research to generate new interventions aiming to influence the size of the SC population in the testis and the potential daily sperm production in the beef bull.Item Effects of Nutrient Restriction, Realimentation, and Parity on Umbilical Hemodynamics in the Pregnant Ewe(North Dakota State University, 2016) Vasquez Hidalgo, Manuel AlexanderSheep are normally managed within grazing systems; forage availability and quality are dependent upon seasonal conditions such as drought and humidity. It is therefore important for producers to know when during gestation it is critical to supplement animals with additional feed. Previous research has shown that nutrient restriction during mid-gestation causes a decrease in umbilical blood flow with a possible consequent decrease in fetal body weight and size. Our findings indicate that a decrease in umbilical blood flow upon nutrient restriction during mid-gestation is not solely a consequence of the restriction itself or an additional effect of parity. Moreover, it appears very probable that such a decrease is also an effect of maternal age during pregnancy. In order to address this question further investigation is needed.