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Articles 1 - 10 of 10
Full-Text Articles in Life Sciences
Corn (Zea Mays L.) Production In Living Mulch Systems, Grazing Potential, And Economic Viability, Marcia Peireira Quinby
Corn (Zea Mays L.) Production In Living Mulch Systems, Grazing Potential, And Economic Viability, Marcia Peireira Quinby
Doctoral Dissertations
Living mulch (LM) is a practice in which forages are grown simultaneously with the main crop, serving as a living cover throughout the growing season. The LM systems were developed to alleviate concerns of soil depletion and finding ways to reduce tillage negative effects on soil productivity. In addition, when legumes are use can decrease the reliance on N fertilizer. The use of corn in LM have been previously studied due to the crop being a large commodity in the U.S.; In addition, the ability to graze the LM after corn production can increase the land use efficiency. To determine …
Wc1 And Tcr Interactions For Γδ T Cell Activation, Alexandria Gillespie
Wc1 And Tcr Interactions For Γδ T Cell Activation, Alexandria Gillespie
Doctoral Dissertations
Major subpopulations of gamma delta T cells within ruminant and pigs are defined by expression of WC1, a hybrid pattern recognition receptor/co-receptor to the T cell receptor (TCR). It is known that when WC1 is knocked down cells fail to respond. Showing that WC1 plays an active role in the stimulation of bovine gamma delta T cells. Here we explored the spatio-temporal dynamics of WC1 and TCR interaction using imaging flow cytometry and stochastic optical reconstruction microscopy. We found that in quiescent gamma delta T cells both WC1 and TCR existed in separate protein domains (protein islands) but after activation …
Identifying Genome Associations With Unique Mastitis Phenotypes In Response To Intramammary Streptococcus Uberis Challenge, Lydia Jean Siebert
Identifying Genome Associations With Unique Mastitis Phenotypes In Response To Intramammary Streptococcus Uberis Challenge, Lydia Jean Siebert
Doctoral Dissertations
Mastitis, the inflammation of the mammary gland, dramatically decreases dairy industry revenues and milk quality, making improved control and prevention methods a goal of the industry. Prior research has observed variation in response to experimental challenge with regards to inflammation indicators, S. uberis concentrations, and the need for antibiotics. To determine possible causes of the observed variation following experimental S. uberis intramammary challenge, we performed genome association analyses (N = 34 – 36 Holstein dairy cows), a linkage analysis, and S. uberis milk inoculation (N = 21 Holstein dairy cows) trials. Association analyses were done using Illumina’s BovineSNP50 BeadChip and …
Alternative Approaches To Improving The Welfare Of Transition Dairy Cows And Their Calves: Use Of Exercise, Randi Alyson Black
Alternative Approaches To Improving The Welfare Of Transition Dairy Cows And Their Calves: Use Of Exercise, Randi Alyson Black
Doctoral Dissertations
Transition cows are the cows most susceptible to disease and prevalence has not changed over the past decade. However, increased physical activity during late gestation may represent a management option to improve transition. Therefore, the objectives of this study were to determine the effect of exercise, pasture turnout, or total confinement on 1.) physical fitness and cortisol concentrations during the dry period, 2.) neutrophil function and behavior during the dry period, 3.) horn growth and wear and sole thickness during the dry period 4.) calving behavior and cortisol concentrations at parturition, and 5.) calf performance, behavior, and cortisol concentrations at …
Evaluation Of Reproductive Efficiency In Lactating Dairy Cows Through Physiologic Evaluation And Synchronization Modification, Charles Dexter Young
Evaluation Of Reproductive Efficiency In Lactating Dairy Cows Through Physiologic Evaluation And Synchronization Modification, Charles Dexter Young
Doctoral Dissertations
Reproductive performance of lactating dairy cows has decreased as milk production has increased as a result of genetic selection. Milk production alone is not the reason for decreased reproductive performance, as fertility issues are multifactorial and collaborative. Research chapters contained within have taken an applied approach focusing in two different areas of fertility. One approach was development of an evaluation system to identify lactating cows with decreased fertility prior to breeding; while another approach was to modify an ovulation synchronization protocol during periods of heat stress in order to improve fertility. The first focus was development and evaluation of a …
Absorption And Utilization Of Choline And Vitamin B12 In Lactating Dairy Cows Using Different Delivery Methods, Virginia Maria Artegoitia Etcheverry
Absorption And Utilization Of Choline And Vitamin B12 In Lactating Dairy Cows Using Different Delivery Methods, Virginia Maria Artegoitia Etcheverry
Doctoral Dissertations
Choline and vitamin B12 are essential nutrients for growth and performances of production animals. However, both nutrients are extensively degraded during digestion in the rumen. This thesis comprised three experiments. First, four cows equipped with a rumen cannula and catheters in the portal vein and a mesenteric artery received a post-ruminal bolus of: 1) cyanocobalamin (CN-CBL) alone (0.1 g) [gram], 2) CN-CBL (0.1 g) + casein (10 g) or 3) CN-CBL (0.1 g) + whey proteins (10 g). After the bolus, blood samples were taken until 24 h [hour] post-bolus. The intestinal absorption of CN-CBL was greater when the vitamin …
Casein Micelles And Their Properties: Polydispersity, Association With Vitamin A And Effect Of Ultra-High Pressure Homogenization, Maneesha Sheenu Mohan
Casein Micelles And Their Properties: Polydispersity, Association With Vitamin A And Effect Of Ultra-High Pressure Homogenization, Maneesha Sheenu Mohan
Doctoral Dissertations
The internal structure of casein micelles is not fully understood. In the present work, we explore some of the basic questions about casein micelles in bovine milk including its size distribution, native binding properties and effect of ultra-high pressure homogenization (ultra-HPH) on technological properties of casein micelles. The size distribution of casein micelles was studied by cryo-TEM using skim milk from four cows. The degree of variation in casein micelle sizes (polydispersity) ranged between 0.39 and 0.47 for a size distribution ranging from 10 to 693 nm. These results indicated high polydispersity of casein micelles in milk from single cows. …
Isolation, Antibiotic Resistance, And Molecular Characterization Of Campylobacter From Poultry, Swine And Dairy Cows, Willie James Taylor
Isolation, Antibiotic Resistance, And Molecular Characterization Of Campylobacter From Poultry, Swine And Dairy Cows, Willie James Taylor
Doctoral Dissertations
This study was conducted to determine presence, antibiotic resistance, and genetic relatedness of Campylobacter on diverse farm types. Cloacal fecal samples from poultry (broilers, layers, and turkey breeders), and fecal rectal samples from non-poultry animals (farrowing sows, finisher pigs, and lactating dairy cows) were tested for Campylobacter using BAM protocols. Agar disk diffusion method was used to determine antibiotic resistance, and PFGE analysis to determine genetic relatedness of isolates recovered within the different farm types. Campylobacter was detected in 34.8% (range of 6.7 to 62.0%, P < 0.001) of cloacal samples from poultry, in 61.4% (range of 55.0 to 69.0%, P < 0.05), and 26.0% (range of 19.0 to 34.0%, P < 0.05) of rectal samples from pigs, and dairy cows, respectively. Antibiotic resistance was detected in 30.2% (range of 0 to 82.4%, P …
Identifying Mechanisms Associated With Innate Immunity In Cows Genetically Susceptible To Mastitis, Alexandra Alida Elliott
Identifying Mechanisms Associated With Innate Immunity In Cows Genetically Susceptible To Mastitis, Alexandra Alida Elliott
Doctoral Dissertations
Mastitis, or mammary gland inflammation, causes the greatest loss in profit for dairy producers. Mastitis susceptibility differs among cows due to environmental, physiological, and genetic factors. Prior research identified a genetic marker in a chemokine receptor, CXCR1, associated with mastitis susceptibility and decreased neutrophil migration. Current research seeks to identify reasons behind mastitis susceptibility by validating this model through in vivo challenge with Streptococcus uberis and studying specific mechanisms causing impaired neutrophil migration. Holstein cows with GG (n=19), GC (n=28), and CC (n=20) genotypes at CXCR1+777 were challenged intramammarily with S. uberis strain UT888. After challenge 68% of quarters from …
Effects Of Weaning Transition And Ionophore On Metabolic Profile And Portal And Hepatic Nutrient Flux During Pre- And Post-Weaning Growth In Dairy Calves, James Levi Klotz
Effects Of Weaning Transition And Ionophore On Metabolic Profile And Portal And Hepatic Nutrient Flux During Pre- And Post-Weaning Growth In Dairy Calves, James Levi Klotz
Doctoral Dissertations
Dairy calf weaning is associated with increases in ketone levels that exceed measured rates of utilization in adults and present a potential energy loss that may be mitigated by ionophores. Therefore, effects of weaning and ionophore supplementation on nutrient metabolism and growth in dairy calves pre- and post-weaning were examined in two experiments. The first experiment consisted of 24 Jersey bulls calves blocked in groups of two according to birth date and weight and randomly assigned to receive either a commercial pelleted starter (CON), or the same diet containing lasalocid (TRT; 83 mg/kg DM) to examine effects of weaning transition …