Animal Sciences electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Division of Animal Sciences. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Multidisciplinary approach to evaluating the impact of corn-based coproducts and fiber deprivation on swine gastrointestinal function and microbiome(University of Missouri--Columbia, 2025) Miller, Hannah Elizabeth; Petry, Amy[EMBARGOED UNTIL 12/01/2026] Corn-derived coproducts are increasingly included into swine diets to help mitigate rising diet formulation costs. These coproducts have increased levels of insoluble dietary fiber (IDF) relative to whole corn, and depending on the milling and extraction process, have varying non-starch polysaccharide composition. Historically, fiber has been considered an antinutrient due to the negative effects associated with digestibility. However, recent work has emphasized its beneficial roles in modulating the gastrointestinal microbiome and promoting host health. This dissertation investigates the effects of insoluble corn-based fiber (ICBF) sources on gut microbiota composition, microbial functional capacity, gastrointestinal morphology, host transcriptomic responses, and nutrient digestibility in growing pigs. Seven experimental diets were formulated, including a fiber-deprived control and six diets with varying sources of ICBF (dehulled degermed corn, ground corn, corn gluten meal, dried distillers grains, high protein dried distillers grains, and corn bran), resulting in a total dietary fiber (TDF) range from <1% to 17.9%. Chapter 2 investigates microbial composition and predicted functional capacity in the jejunal, ileal, and colonic mucosa, while Chapter 3 focuses on the cecal mucosa and digesta. Overall, the inclusion of ICBF sources uniquely modulates the mucosal and luminal associated microbiota in each location. Increasing TDF resulted in a richer and more diverse microbiome. However, both fiber deprivation and high inclusion of IDF were associated with reduced microbial capacity for fiber fermentation and a greater metabolic capacity for degradation of mucins and other host-derived substrates. Meanwhile diets with more moderate fiber inclusion had increased abundance of beneficial bacteria like Bifidobacterium and Lactobacillus and an increased metabolic capacity for fiber fermentation. Simultaneously, transcriptomic analysis revealed upregulation of genes involved in mucin production, extracellular matrix remodeling, and antimicrobial peptides in diets which included ICBF. Conversely, fiber deprived diets resulted in microbial dysbiosis, impaired gastrointestinal morphology, and gene expression profiles associated with inflammation and tissue degradation. Chapter 4 examines the temporal adaptation of the fecal microbiome and total tract digestibility. Pigs fed diets which included ICBF exhibited more rapid microbiome stabilization compared to fiber devoid fed pigs. Additionally, moderate-high fiber diets had microbial functional profiles more capable of fermenting corn-derived hemicellulose, KEGG pathways associated with carbohydrate metabolism, and increased total short chain fatty acids. Despite the functional improvements of the microbiome, increasing the level of IDF in the diet did result in reduced total tract digestibility of gross energy, dry matter, IDF, and nitrogen. Collectively, this work highlights the complex interactions between dietary fiber, the gastrointestinal microbiome, and host physiology in swine. It provides insight into microbial community structure and function which may inform the development of future nutritional strategies including prebiotics, probiotics, postbiotics, or targeted dietary enzymes to improve fiber utilization in swine.Item Mechanisms governing endometrial epithelial specification : insights from development and disease(University of Missouri--Columbia, 2025) Rizo Gonzalez, Jason Alberto; Kelleher, Andrew M.; Spencer, Thomas E.Differentiation of the female reproductive tract (FRT) epithelium is fundamental to reproductive health and function. At birth, FRT epithelial cells exhibit developmental plasticity and can differentiate into either a columnar type in the oviduct and uterus or stratified squamous with basal cells in the cervix and vagina. Disruptions in these differentiation programs have been linked to FRT pathologies, including squamous metaplasia and endometrial cancer. Despite the significance of these developmental processes, early epithelial fate decisions remain largely uncharacterized and represent a significant gap in our understanding of epithelial biology within the FRT. Therefore, this dissertation aimed to: (1) define the temporal and molecular regulation of epithelial plasticity in the neonatal uterus; and (2) determine how epithelial–stromal interactions and estrogen receptor alpha (ESR1) signaling contribute to epithelial specification and homeostasis. These aims were addressed using endometrial organoids, epithelial–stromal assembloid co-cultures, multiomic approaches, and mouse genetic models. The results from these studies established that: (1) uterine epithelial plasticity declines rapidly after birth, with progressive restriction toward a lineage-committed columnar fate; (2) uterine stromal cells inhibit squamous epithelial differentiation and promote columnar identity through paracrine signalling; (3) epithelial-specific loss of ESR1 activates luminal-to-basal differentiation programs in the uterus, marked by the emergence of p63+/KRT5+ epithelium; (4) estrogen signalling regulates epithelial fate in part through ESR1- dependent stromal mechanisms; and (5) conserved molecular programs underlie epithelial plasticity in both neonatal development and disease states, suggesting that pathological conditions may involve reactivation of neonatal plasticity programs. Collectively, these studies establish ESR1 as a critical regulator of uterine epithelial fate specification and provide a developmental framework to understand how disruptions in epithelial identity may contribute to the etiology of FRT pathogenesis.Item A functional analysis of growth hormone receptor promoter regions in swine(University of Missouri--Columbia, 2025) Denton, Alicia Nicole; Lucy, Matthew; Safranski, Timothy[EMBARGOED UNTIL 08/01/2026] Growth hormone (GH) and its receptor (GHR) play critical roles in regulating growth, development, and reproductive function in animals. GHR expression in the liver is critical for postnatal growth and is regulated by tissue-specific promoters. While promoter 1 (P1) is considered the primary hepatic promoter in species such as cattle, the role of P1 and promoter 2 (P2) in pigs remains poorly defined. This study used CRISPR/Cas9 to generate pigs with bi-allelic knockouts of either P1 (P1KO) or P2 (P2KO) to evaluate the promoter-specific regulation of hepatic GHR signaling and systemic growth. P1KO pigs exhibited normal hepatic GHR and IGF1 expression, normal circulating GH and IGF1 concentrations, and no differences in postnatal growth compared with wildtype (WT) littermates. In contrast, P2KO pigs showed marked reductions in GHR1B, total GHR, and IGF1 mRNA in both liver and muscle, accompanied by elevated circulating GH and lower IGF1 concentrations compared with WT. These endocrine changes were associated with impaired postnatal growth, with P2KO pigs consistently weighing less than WT animals. Despite this, P2KO females were capable of lactation, though fetal growth and litter size were reduced. These findings suggest that promoter 2, not promoter 1, is the primary regulator of hepatic GHR expression and somatotropic axis coupling in pigs. The results highlight species-specific differences in GHR regulation and underscore the functional importance of promoter 2 in supporting postnatal growth and metabolic function. This study also demonstrates the efficacy of targeted gene editing to dissect promoter-specific gene function in livestock.Item Transcriptional profiling of cumulus cells from fli-matured oocytes identifies junctional genes as key components in oocyte maturation(University of Missouri--Columbia, 2025) Green, Caroline Laura; Lee, Kiho; Redel, Bethany[EMBARGOED UNTIL 08/01/2026] The production of genetically engineered pigs for biomedical and agricultural purposes requires performing in vitro oocyte maturation and embryo culture. Additionally, in vitro maturation can play a key role in the preservation of important genetic lines and expanding the population of genetically valuable pigs. However, oocytes and embryos are exposed to a suboptimal in vitro environment, which can compromise their viability. Recent improvements to in vitro maturation media, including the addition of FGF2, LIF, and IGF1 (FLI), have increased the frequency of oocytes that reached the metaphase II stage, doubled the number of oocytes that reached the blastocyst stage, and quadrupled the number of piglets born after embryo transfer. Despite these benefits, the underlying cellular mechanisms remain poorly understood. Given the essential role of cumulus cells (CC) in oocyte maturation, we investigated how FLI affects CC gene expression. Cumulus-oocyte complexes (COC) were matured for 24 h in either control or FLI-supplemented media. CC originating from a single oocyte that reached the blastocyst stage was analyzed by using RNA sequencing. A total of 1,533 transcripts were differentially expressed. Of these, 511 were upregulated and 1,022 were downregulated in the FLI CC (adj-p < 0.05). Gene ontology analysis revealed cellular response to leukemia inhibitory factor was significantly upregulated in FLI-treated CC. The gene ontology term enriched among the downregulated genes in FLI matured CC was extracellular matrix organization. Notably, the CC from FLI matured oocytes showed differential gene expression related to junctional communication. Tight junction protein 2 (TJP2), cadherin 8 (CDH8), gap junction protein α5 (GJA5) and were upregulated in CC from FLI matured oocytes, while cadherin 9 (CDH9) and cadherin 22 (CDH22) were higher in control CC. To further investigate the effects of FLI on tight, gap, and adherens genes, we expanded our list of genes of interest to include tight junction protein 1 (TJP1), gap junction protein α1 (GJA1), and gap junction protein α4 (GJA4). Immunofluorescence confirmed the significantly elevated expression of tight junction proteins (TJP1, TJP2) and GJA4 in FLI-treated COCs, whereas GJA1 and GJA5 were more abundant in controls. However, adherens junction proteins CDH8, CDH9, and CDH22 did not differ significantly between groups. To evaluate cytoplasmic maturation, we assessed mitochondrial distribution, protein synthesis, and cortical granule localization. No significant differences were observed in mitochondrial intensity or protein synthesis between groups. However, cortical granule localization indicated a higher rate of exocytosis in FLI-treated COCs, potentially suggesting more advanced cytoplasmic maturation. These findings demonstrate that FLI supplementation modulates gene expression in CC, particularly those involved in cell-cell communication via junctional complexes. Furthermore, FLI may enhance cytoplasmic maturation as evidenced by cortical granule dynamics. These insights support the use of FLI to improve porcine IVM systems and provide a foundation for future research to increase oocyte developmental competence and embryo viability.Item Evaluating fiber and stimbiotic supplementation during the transition and lactation periods on litter performance and sow physiology(University of Missouri--Columbia, 2025) Self, Rachel Marie; Petry, Amy[EMBARGOED UNTIL 08/01/2026] In recent decades, the metabolic and physiological demands on the commercial sow have increased substantially as genetic selection has intensified expectations for higher farrowing rates and pigs per sow per year (Rathkölb et al., 2023). Consequently, the sow's nutrient and energy requirements have also increased. One of the most critical phases in meeting these heightened demands is the transition period, spanning approximately 7--10 days before farrowing through 3--5 days post-farrowing (Theil et al., 2022). During this time, sows undergo substantial hormonal, physiological, and metabolic changes, often resulting in reduced feed intake, slowed gut motility, and an increased incidence of constipation (Verghese et al., 2015). These factors elevate the risk of negative energy balance, which can impair colostrum quality, increase farrowing complications, and reduce piglet viability and survival. -- page 1