Animal & Avian Sciences Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/2741

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CIRCULATION FANS AND BROILER WELFARE IN COMMERCIAL BROILER HOUSES
(2022) McMillian, Zoie Nicole; Weimer, Shawna; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Footpad dermatitis (FPD) is a welfare concern in broiler houses today that is often caused by inadequate management of living conditions. The objective of this study was to evaluate the effect of high-capacity circulation fans on house litter moisture, temperature, relative humidity, noise volume, and broiler body weight, FPD prevalence and severity, hock burn prevalence, feather cleanliness, and behavior from 2 organic commercial flocks. For both flocks, two houses had 16 high-capacity circulation fans (Houses 1 and 2) and two did not (Houses 3 and 4). Welfare assessments took place when the birds were 3 and 6 weeks of age. With both flocks combined, a greater prevalence of FPD (P=0.001) and hock burn (P=0.0002) was observed for birds in the houses without fans than in the houses with fans at week 6. Flock 1 birds in the houses without fans had greater FPD lesion areas (P=0.0001) and FPD severity scores (P=0.0004) than birds in houses with fans. In Flock 2, there were more small birds in the houses without fans at week 6 (P≤0.03). The results of this study indicate that high-capacity circulation fans in commercial broiler houses could positively impact FPD and hock burn prevalence, FPD severity, and flock uniformity.
COMMUNITY STRUCTURES OF GUT MICROBIOME UNDER DIFFERENT DIETS IN ANGUS BEEF CATTLE
(2019) Liu, Jianan; Song, Jiuzhou; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The microbiota of animals’ digestive tract plays important roles in health, nutrient utilization, and performance. For ruminants, the digestive tract, including rumen and other gastro-intestinal regions, hosts a unique and diverse microbiome that aids feed fermentation, digestion, and absorption. We hypothesize that compositions of diets can influence microbiomes and further affect the production of VFA and the composition of bile acids in beef cattle. We used rectum microbiota as a baseline and examined the microbiome in rumen and jejunum by16S-seq, together with quantifications of VFAs, lactate, and bile acids under grass-feeding and grain-feeding. We found that microbial communities displayed significant differences in microbiome structure and VFA production. Moreover, increased VFAs in grain-fed group may trigger lactate-associated bacteria growth. Bile acids could promote the growth of bacteria that had abilities of secondary bile acids conversion. These results provided deep insights into differences in beef quality and bovine biology under different diets.
The effect of feeding mixed tocopherol oil on body accumulation and immune cell functions in lactating holstein dairy cows
(2017) QU, YANG; Moyes, Kasey M; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Non-α-tocopherol (i.e. β, γ, and δ-tocopherol) supplements are as important as α-tocopherol with regard to maintaining lactating dairy cow health. However, information on non-α-tocopherol bioaccumulation and its effects on immune cell function is not available. A series of experiments were conducted to investigate the effect of mixed tocopherol oil supplement (Tmix; i.e. α, β, γ, and δ-tocopherol) on body accumulation and immune cell functions of the lactating Holstein dairy cow. Tissue, tissue mitochondria, blood and milk were collected from lactating dairy cows to measure the concentration of all four tocopherol isoforms via Tmix supplementation. In addition, polymorphonuclear leukocyte (PMN) were isolated to investigate the effect of Tmix on its function and immune gene expression. In the first experiment, Tmix increased γ-tocopherol concentrations but did not increase the α-tocopherol concentration in three different types of tissues (i.e. liver, mammary gland and muscle) and liver mitochondria. Within those three different types of tissues, liver showed the highest ability to store tocopherol isoforms (i.e. α- and γ-tocopherol) compared to the other two tissues. Also, amounts of α- and γ-tocopherol were detected in liver mitochondria, but limited amounts were detected in mammary gland mitochondria. In the following experiment, Tmix increased γ-tocopherol concentration in milk and blood as determined via every 8 h and daily measurements. Compared to γ-tocopherol, α-tocopherol showed the highest concentration of the tocopherol isoforms in milk and blood. Limited quantities of β- and δ-tocopherol were detected in milk and blood via Tmix supplementation. In the last experiment, Tmix increased PMN chemotaxis function and did not impair the whole blood respiratory burst response of dairy cows, which might be associated with non-α-tocopherol existing in Tmix. Even though Tmix increased the expression of pro-inflammatory genes in PMN, those are needed during the initial immune activation. Overall, the results of the experiments demonstrated that short-term supplementation with Tmix could compensate γ-tocopherol without altering α-tocopherol in dairy cows. The liver showed the highest capability of accumulating tocopherol isoforms compared to the mammary gland and muscle. In addition, Tmix did not harm immune functions or have any apparent effects on animal health in lactating Holstein dairy cows.
ESTIMATION OF DRY MATTER INTAKE AND IDENTIFICATION OF DIETARY AND PRODUCTION PARAMETERS THAT INFLUENCE FEED EFFICIENCY OF INDIVIDUAL DAIRY COWS
(2019) Iwaniuk, Marie Elizabeth; Erdman, Richard A.; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The objectives of this dissertation were to: 1) develop and validate equations used to estimate individual cow dry matter intake (DMI; kg/d) based on a nitrogen (N) balance approach, 2) determine the discriminatory power of several biological, production, and dietary variables on dairy feed efficiency (FE) as defined as energy-corrected milk (ECM; kg/d) per unit of DMI, 3) repeat the second objective using residual feed intake (RFI) to indicate FE status, and 4) determine if RFI values are dependent on the equation utilized to estimate DMI. Results from the first experiment (Chapter 3) indicated that DMI could be successfully estimated on an individual cow basis using the following commonly measured parameters: milk yield, milk protein concentration, body weight (BW; kg), and dietary N concentration. These inputs are relatively simple to measure; therefore, this equation may be used in the dairy industry as a practical method to estimate individual cow DMI when cows are fed in a group setting. The results of the second experiment (Chapter 4) suggested that days in milk (DIM), milk fat yield (g/d), and BW had the most discriminatory power (89% success rate) to discriminate between cows based on their FE status when FE was defined as ECM per unit of DMI. Therefore, dairy producers can use these 3 variables to select for cows with high FE without requiring the measurement of DMI which can be costly and difficult to obtain. Observations from the third experiment (Chapter 5) suggested that RFI is indicative of differences in metabolic efficiency between cows independent of most biological, production, and dietary variables, except DIM. These results are consistent with other studies that have suggested that RFI is indicative of true differences in metabolic efficiency between cows regardless of production parameters. Lastly, the results of the fourth experiment (Chapter 6) suggest that RFI values generated from different DMI equations are strongly correlated such that RFI values are independent of the DMI equation utilized in the calculation. Thus, dairy producers can select the equation to estimate DMI that is most suitable for their operation without causing an “equation bias” on the RFI calculation.
MODULATING KEY GENES INVOLVED IN PANCREAS FORMATION AND INSULIN SIGNALING USING CRISPR/CAS9 IN THE PIG
(2019) Sheets, Timothy P; Telugu, Bhanu P; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Among the metabolic diseases, diabetes remains a “pressing problem” as recognized by World Health Organization, not only due to the impact on individuals’ lives, but also because of the rapid increase in newly diagnosed patients. To better understand the mechanisms of diabetes, this dissertation investigates the role of NGN3 in pancreas development using CRISPR/Cas9 gene targeting in the pig model. NGN3 was selected for study because of its critical role in endocrine pancreas formation. Our research demonstrates that the targeted ablation of NGN3 blocks development of the endocrine pancreas, a finding supported through gene expression analysis. Furthermore, follow-up studies show that clonal piglets derived from NGN3-ablated animals lack the major endocrine islet cell types and subsequent expression of key endocrine hormones. This porcine model provides valuable insights into the study of type 1 diabetes in early post-natal life and future applications of human-to-pig chimeric organ development for transplant surgery. Expanding upon this porcine model for diabetes, we sought to apply this approach to the study of type 2 diabetes using a novel pig model, thus bridging the gap between mouse and human. For this endeavor, we identified GRB10 as a potential critical mediator in insulin signaling, development, and growth potential following an extensive literature review. The potential for dual applications in both agriculture and medicine was also identified as an objective. Analysis of qPCR data from in vitro overexpression studies supports that GRB10 modulates insulin signaling through the canonical insulin pathway. Additional data from two in vivo gene editing trials targeting the GRB10 locus in both Ossabaw and domestic pig breeds show a supportive qualitative trend towards growth regulation in the Ossabaw pig breed. Further evidence is required to determine whether GRB10 plays the same role in the domestic pig, as a limited cohort size of mutants precluded an extensive analysis of phenotypes. Together, our assessment of NGN3 and GRB10 offer significant potential for modeling of both type 1 and type 2 diabetes as well as modeling of growth traits in the pig through application of advanced genome engineering technology.