Animal Sciences electronic theses and dissertations (MU)
Permanent URI for this collection
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.
Browse
Recent Submissions
Item Consumer evaluation of pork loins as influenced by firmness, marbling and leanness(University of Missouri--Columbia, 1967) Russell, James Lowell; Hedrick, H. B."Objectives of this study. The objectives of this investigation were: (1) to test the consumer acceptance of three different types of pork loins; Firm Marbled, Lean Soft, and Lean Firm: (2) to compare results when members of the panel were subjected to two test situations, Single Stimulus and Paired Comparison: (3) to determine if moisture and ether extractable constituents of the lean and other carcass characteristics have an influence upon the consumer acceptance of loin chops and: (4) to determine if tenderness as measured by the Warner-Bratzler shear device is related to consumer acceptance."--Page 3.Item Acentriolar microtubule organizing centers regulate spindle positioning in the mouse zygote(University of Missouri--Columbia, 2025) Leara, Kathleen; Balboula, Ahmed Z.[EMBARGOED UNTIL 12/01/2027] Asymmetrical division leading to uneven blastomere size during early embryo development is associated with decreased implantation and pregnancy rates in humans. Given that the spindle position within the cell dictates the cleavage plane, the success of symmetrical division after fertilization depends on its location at the center of the cell. The formation and positioning of the spindle depend on microtubule filaments, a major cytoskeletal component of the cell. In mice, the zygote lacks centrosomes but contains acentriolar microtubule-organizing centers (MTOCs) that form the poles of the first mitotic spindle. Thus far, the biological significance of MTOCs in spindle positioning remains unexplored. We used a transgenic mouse model expressing Cep192-eGFP to visualize MTOCs in live one-cell embryos and depleted MTOCs via multiphoton laser ablation to understand the functional role of MTOCs. We demonstrate that the localization of MTOCs to pronuclei is dependent on microtubules and F-actin. We also find that MTOCs regulate spindle positioning in zygotes, a previously unknown phenomenon. These findings help to understand the factors that regulate spindle positioning in early mammalian embryos, ensuring the faithful placement of the cleavage plane and highly symmetrical division.Item Impact of FLI on porcine preimplantation embryo development in vitro(University of Missouri--Columbia, 2025) Jaworski, Aleah Renae; Redel, Bethany; Lee, Kiho[EMBARGOED UNTIL 12/01/2026] In vitro production of porcine embryos is a vital component of biomedical and agricultural advancements, with swine serving as essential models for human diseases and playing a key role in genetic improvement efforts for livestock production. Despite progress, current in vitro maturation (IVM) systems still yield suboptimal developmental outcomes, as evidenced by low blastocyst formation and reduced embryo viability. Recent investigations have highlighted the potential of a supplement of three cytokines found in follicular fluid, fibroblast growth factor 2 (FGF2), leukemia inhibitory factor (LIF), and insulin-like growth factor 1 (IGF1), together referred to as “FLI”, to enhance oocyte maturation and subsequent embryonic development (Yuan et al., 2017). Many studies have shown that FLI activates critical proliferation signaling pathways such as MAPK1/3 and AKT when added during maturation (Procházka et al., 2021; Yuan et al., 2017). Currently, even with advancements in transcriptional profiling and the addition of new components to improve blastocyst development, such as arginine and glutamine, the in vitro culture (IVC) environment is still in need of additional optimization (Chen et al., 2018; Redel et al., 2015). This study investigates the effects of supplementing culture medium with FLI during porcine preimplantation embryo development. The primary objective is to determine if FLI supplementation during culture enhances blastocyst formation and improves overall embryo competency. Sow oocytes were obtained and used for in vitro fertilization and were subsequently cultured with FLI on days 0, 2, 3, or 4. On day 6, blastocyst formation and total cell number was assessed to identify the optimal day for FLI supplementation to have the most profound effect on embryo development. The developmental competence of FLI-treated blastocysts was evaluated by analyzing the total cell number, assessment of inner cell mass (ICM) and trophectoderm (TE) number, and timing of blastocyst development and hatching on days 5, 6, and 7. This research aims to identify methods to refine in vitro production (IVP) protocols, possibly reducing the number of embryos required for transfer and improving the efficiency of porcine embryo production.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 Nutritional management of yearling beef heifers and primiparous cows : links between growth, metabolic indicators, and reproductive outcomes(University of Missouri--Columbia, 2025) Ricardo, Kimberly Renee; Thomas, Jordan M.; Bailey, Eric A.Nutrient intake is a key regulator of reproductive efficiency in beef females because of its influence on energy status, ovarian activity, and the timing of estrous cyclicity in beef heifers and the primiparous beef cow. This thesis evaluated how targeted nutrient supplementation during two critical developmental periods, the second breeding season of primiparous beef cows and prebreeding development in yearling beef heifers, affects growth, reproductive maturity, fertility outcomes, and responsiveness to estrus synchronization. The overarching objective of this thesis was to determine whether nutrient supplementation can improve reproductive outcomes and productivity in young beef females. The objective of Chapter 2 was to evaluate whether targeted nutrient supplementation during the breeding season could mitigate effects of negative energy balance and improve reproductive performance in fall-calving primiparous beef cows. Fall-calving primiparous beef cows (n = 49) received either no supplement (CON; n = 24) or a commercially formulated supplement (SUP; 4.08 kg·hd⁻¹·d⁻¹; n = 25) while consuming tall fescue hay. Supplemented cows had greater body weight (BW) at the end of supplementation (469 vs. 434 kg; P = 0.01) and lost less BW from Days 0 to 74 (−0.09 vs. −0.38 kg/d; P = 0.01). Calf weaning weight performance did not differ statistically, though unadjusted weaning weight tended to be higher for SUP calves than CON cows (210 vs. 195 kg; P = 0.08). Follicle diameter at synchronization did not differ (12.5 vs. 11.7 mm; P = 0.22), and pregnancy rates to AI were modestly higher for SUP cows than CON (50% vs. 40%, respectively ). Circulating NEFA and BHB concentrations were similar between treatments, though NEFA exhibited a treatment × date interaction (P = 0.03), indicating differences in energy metabolism across the breeding period. These results indicate that nutrient supplementation during the breeding season modestly improved BW outcomes and reduced BW loss, with modest improvements in fertility. In Chapter 3, the objective was to determine whether increasing nutrient supplementation during heifer development in a tall fescue-based forage system could enhance prebreeding growth and advance puberty onset prior to breeding. Heifers were developed to achieve either 50% or 65% of mature BW using two supplementation levels. Heifers developed to 65% of mature BW had greater BW during mid-postweaning development (285 vs. 262 kg; P = 0.01) and prior to the breeding season (329 vs. 266 kg; P = 0.01), with a higher average daily gain (ADG) throughout the entirety of the 113-d development period (0.80 vs. 0.28 kg/d; P = 0.01). A greater proportion of 65% treatment heifers had attained puberty at the start of estrus synchronization (50% vs. 3%; P < 0.01) based on ovarian development, and pelvic area was larger (147 vs. 143 mm²; P = 0.01) for the 65% treatment heifers compared to the 50% treatment heifers. Following estrus synchronization, a greater proportion of 65% treatment heifers expressed estrus prior to split-time artificial insemination (STAI) compared with 50% treatment heifers (94% vs. 66%; P = 0.005). These results indicate that achieving 65% of mature BW at breeding improved prebreeding growth and advanced reproductive maturity in yearling beef heifers grazing tall-fescue pastures. The findings from these two experiments demonstrate that targeted nutrient supplementation during physiologically demanding stages (i.e., the second breeding season in primiparous beef cows and prebreeding development in replacement beef heifers), supports growth, enhances reproductive readiness, and may improve reproductive outcomes. Such strategies can enhance herd longevity, productivity, and sustainability within beef cow–calf systems.