Theses and Dissertations at Montana State University (MSU)
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Item A comparative approach to refine molecular mechanisms impacting meat quality and carcass characteristics(Montana State University - Bozeman, College of Agriculture, 2021) Schumacher, Madison Lee; Chairperson, Graduate Committee: Jennifer Thomson and Jane A. Boles (co-chair)Fat deposition is important to both producers and consumers. Producers decide when to harvest animals based on a fat endpoint while consumers equate marbling to tenderness. USDA quality grade is determined by physiological age and marbling. While quality grades help provide insight about product palatability, there is too often variation within the same quality grade. The control of fat deposition is important to determination of carcass endpoint and efficiency of production. The purpose of this study was to increase our understanding of the regulation of fat deposition and muscle growth in relation to USDA quality grade, and to utilize a species comparison to highlight genes and pathways regulating these tissues in multiple meat producing species. Fifteen wethers and fifteen steers from the Red Bluff Research Center were fed to end points that represented Standard, Select, and Choice quality grades endpoints for steers while sheep were fed to fat thicknesses typical to industry endpoints. Subcutaneous adipose tissue and muscle samples were collected for gene expression analysis. Loin were removed from each animal for shear force analysis. Shear force analysis showed a significant reduction in shear force values as quality increased in beef (p < 0.05). RNA extracted from the adipose and muscle tissue was sent to Novogene for RNAseq analysis. The largest difference observed in this study was found within the ovine muscle tissue. Comparing Class 3 to Class 1 muscle tissue resulted in 723 genes down regulated and 1,853 genes up regulated. Class 3 to Class 2 showed 1,127 genes down regulated and 2,272 genes up regulated. When comparing bovine samples, there was an equal distribution of up and down regulated genes. Differentially expressed genes were associated with fat metabolism, cellular signaling, and inflammation in beef. Poor annotation limited the functional analysis of differentially expressed genes in sheep. This study emphasized the need for additional studies evaluating the relationship between gene expression and fat deposition.Item Prevalence and production impacts of subclinical mastitis in extensively managed ewes(Montana State University - Bozeman, College of Agriculture, 2019) Knuth, Ryan Michael; Chairperson, Graduate Committee: Megan Van Emon; W. C. Stewart, J. B. Taylor, C. J. Yeoman, B. Bisha, M. L. Van Emon and T. W. Murphy were co-authors of the article, 'The prevalence and etiology of subclinical mastitis and association with milk somatic cell count in western range flocks' submitted to the journal 'Journal of animal science' which is contained within this thesis.; W. C. Stewart, J. B. Taylor, C. J. Yeoman, M. L. Van Emon and T. W. Murphy were co-authors of the article, 'Udder morphometry and health and their relationship with ewe somatic cell count and productivity in extensively manged research flocks' submitted to the journal 'Journal of animal science' which is contained within this thesis.Mastitis results from a bacterial infection of the mammary gland and is a devastating disease to all sheep producers from both an economic and animal welfare perspective. Clinically infected ewes display visually apparent symptoms, however, subclinically infected ewes do not although this form is more common. Since milk is a direct commodity of dairy animals, much of the past research has been conducted here and the production and economic impacts of subclinical mastitis are less clear in non-dairy (e.g., meat- and wool-type) ewes. The objectives of the first study were to identify bacteria species present in milk collected from clinically healthy ewes and evaluate somatic cell count (SCC) thresholds relating to intramammary infection. Milk samples were collected from two research flocks in the Western U.S. (Montana State University = MSU; U.S. Sheep Experiment Station = USSES). Bacteria were identified by both culturing and identification via mass spectrometry and polymerase chain reaction methods. Overall, 60 bacteria species were identified using mass spectrometry and the most common belonged to the Bacillus and Staphylococcus genera. The ideal SCC thresholds to predict intramammary infection ranged between 240 x 10 3 to 1370 x 10 3 cells/mL, depending on the flock and time of collection. In the second study, milk samples were collected and udder and teat morphometric traits were observed to predict ewe productivity via dam 120 day adjusted litter weaning weight (LW120). Udder and teat characteristics were assessed on a linear scale at each sampling and included teat length, udder symmetry, and presence of supernumerary teats, to name a few. The effect of log10-transformed SCC (LSCC) on ewe productivity was dependent on lactation stage and production year, but when significant, indicated a 9.2-14.7 kg reduction in LW120 associated with a 1-unit increase in LSCC. Factors which influenced LSCC included parity, production year, and presence of supernumerary teats in USSES ewes and, for MSU ewes, included teat length, external teat damage, udder symmetry, and presence of supernumerary teats. The results indicate subclinical mastitis is common and additional studies investigating techniques to mitigate its severity and prevalence in meat- and wool-type ewes are warranted.Item Utilizing sugar beets in steer backgrounding, sheep nutrient metabolism, and silage(Montana State University - Bozeman, College of Agriculture, 2017) McGregor, Ian Robert; Chairperson, Graduate Committee: Megan Van Emon; C. M. Page, W. C. Stewart and M. L Van Emon were co-authors of the article, 'Effects of sugar beets on steer backgrounding performance, sheep nutrient metabolism, and ruminal characteristics' submitted to the journal 'Journal of animal science' which is contained within this thesis.; J. G. P. Bowman, C. M. Page, A. R. Hubbard, M. Manoukian, W. C. Stewart, and M. L Van Emon were co-authors of the article, 'The effect of ensiling sugar beets on preservation characteristics, nutrient profile, and in situ disappearance' submitted to the journal 'Journal of animal science' which is contained within this thesis.Non-harvested sugar beets are an abundant yet underutilized feedstuff for producers in Montana and Northern Plains region. A performance and metabolism study were performed to observe the effects of sugar beets on steer backgrounding performance, sheep nutrient metabolism, and rumen fermentation characteristics. Both experiments utilized four dietary treatments where sugar beets replaced 0% (0SB), 15% (15SB), 30% (30SB), and 45% (45SB) of barley on a dry matter (DM) basis. Forty eight Angus steers were used in a completely randomized design to conduct the 50 d performance study. Average daily gain (ADG), feed efficiency (G:F), and dry matter intake (DMI) weren't affected by treatment (P > or = 0.06). A 4 x 4 replicated Latin Square design was used to observe the effects of increasing dietary inclusion of sugar beets on nutrient metabolism and rumen fermentation characteristics of eight growing wethers. Crude fiber, DM, and nitrogen (N) digestibility weren't affected by treatment (P > or = 0.10), while N balance demonstrated a cubic effect (P = 0.04). Butyrate concentration demonstrated a treatment x time effect (P = 0.01), where butyrate concentrations increased with increasing sugar beets in the diet at 1300. The acetate to propionate ratio demonstrated a linear increase (P = 0.03) with increasing sugar beets in the diet. Overall, we concluded that sugar beets can be included up to 45% of the diet without inducing any deleterious effects on steer performance or sheep nutrient metabolism. However, the moisture content of sugar beets creates difficulty when storing this feedstuff, and we hypothesized that sugar beets may ensile well with other feedstuffs. Therefore, we carried out a study to test this hypothesis using a 3 x 2 factorial design. Treatments were hay (H), or sugar beets mixed with either hay (SBH) or soybean meal (SB) were ensiled at a rate of 50:50 (as fed) with or without a mold inhibitor. The pH of all treatments fell below 5.0 before d 90 (P < 0.01). All treatments increased in crude fiber and crude protein over time (P < or = 0.03). With these results, we conclude that sugar beets can be effectively ensiled with hay or soybean meal.Item The effects of self-feeding various levels of safflower hulls in pellet form for maintaining yearling ewes(Montana State University - Bozeman, 1964) Brownson, RogerItem Sheep management on Moroccan rangelands(Montana State University - Bozeman, 1984) El Abbassi, MohamedItem The effects of sheep grazing for Pisum sativum or Melilotus officinalis cover crop termination(Montana State University - Bozeman, College of Agriculture, 2016) Westbrook, Jasmine Katherine; Chairperson, Graduate Committee: Craig CarrIntegration of sheep grazing into crop rotation systems has been proposed as an alternative to conventional cover crop management techniques. However, the effectiveness of this approach and its impact on subsequent crops has not been evaluated in Montana. This study assessed the use of sheep (Ovis aries) grazing to terminate field pea (Pisum sativum) and yellow sweetclover (Melilotus officinalis) cover crops used in rotation with winter wheat. Cover crops were terminated using either rotational or continuous grazing treatments and their effects on cover crop termination, sheep live weight gains, and winter wheat emergence and yield were quantified. Sheep grazing for cover crop termination was also compared to chemical termination and mechanical tillage. In 2013, yearlings grazed the winter pea cover crop for 32 days. Sheep grazing was an effective termination method (77% dead, 1% live, 22% bare ground). Average daily gains (ADGs) did not differ between grazing treatments with sheep exhibiting ADGs of 0.181 kg day -1 for rotational (230 sheep ha -1)and 0.154 kg day -1 for continuous (57 sheep ha -1) treatments (P = 0.12). Winter wheat seedling emergence post grazing was higher under the continuous grazing treatment (P = 0.017), however winter wheat yield did not differ between treatments (P = 0.91). Results indicated grazing was a viable method for terminating a pea cover crop. In 2014, yearlings grazed the sweetclover cover crop for 40 days. Sheep grazing at stocking densities of 44 and 178 sheep ha -1 did not provide effective termination (40% dead, 34% live, 9% bare groundcover). Average daily gains did not differ between grazing treatments with sheep exhibiting ADGs of 0.177 kg day -1 for rotational and 0.172 kg day -1 for continuous treatments (p = 0.79). Termination was achieved using a second group of sheep at stocking densities of 119 and 477 sheep ha -1. Winter wheat seedling emergence did not differ between grazing treatments (p = 0.95). Winter wheat yield was lower in grazed plots than tilled and chemically terminated plots. Grazing has the potential for effective cover crop termination comparable to tillage or herbicide, but results may vary with cover crop species.Item The in vitro digestibility and utilization of Big Sagebrush and Black Sagebrush(Montana State University - Bozeman, College of Agriculture, 1985) Striby, Karl DavidItem Studies on fecal analyses for determining forage species and protein in the diet of range ewes(Montana State University - Bozeman, College of Agriculture, 1951) McKinney, MarkItem A comparison of three range measurement techniques and a study of the response of native vegetation to protection from sheep grazing(Montana State University - Bozeman, College of Agriculture, 1960) Vogel, W. G.Item The effect of aureomycin upon lamb mortality and body weights and the effect of delayed feeding upon weaning weights(Montana State University - Bozeman, College of Agriculture, 1957) Bassett, James Wilbur