Theses and Dissertations at Montana State University (MSU)
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Item Impact of cattle feeding-style on beef and human postprandial inflammation(Montana State University - Bozeman, College of Education, Health & Human Development, 2024) Spears, Meghan Leigh; Chairperson, Graduate Committee: Mary P. Miles; This is a manuscript style paper that includes co-authored chapters.Purpose: Various cattle-feeding styles have arisen in recent years, impacting the sustainability and environmental practices of many producers. While these changes are known to have an impact on the environment, little is known about the direct impact cattle raised using different feeding styles has on human health. Acute response focused studies, like this, are a glimpse into the expected impact of a certain food on the diet over time. The purpose of this study is to investigate the impact of cattle-feeding style on postprandial inflammation. Methods: A randomized, double blind, crossover study design was used to compare grass-fed (GRA) and conventional (CON) beef. Subjects (n=10) were comprised of men and women with a healthy body mass index (BMI) and no preexisting metabolic conditions. Blood samples were collected fasted and postprandially for four hours. Blood samples were analyzed for inflammation markers (TNF-alpha, IL-23, IL-17, IL-10, IL-1beta, IL-6, IFN-gamma and GM-CSF) at hourly timepoints. To observe postprandial changes with and without consideration for cattle feeding style, the net area under the curve (AUC) was calculated. Maxchange and CMAXtime were calculated by finding the maximum value of each cytokine between hours one and hour postprandially and subtracting that from the fasting value. CMAXtime represents the time at which the maximum value of each cytokine was reached in hours. Maxchange and AUC responses were compared to zero using a one-sample t-test to determine if response was greater than fasting. Results: In response to beef, maxchange of all measured markers and IFNgamma AUC were significantly greater than zero (p< 0.05). No differences were shown between GRA and CON in inflammation AUC (p> 0.05). Conclusion: This demonstrates that beef consumption does increase postprandial inflammation, but cattle-feeding style does not significantly impact this response.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 Effect of temperament and growth rate on tenderness of beef steaks from Simmental cross steers(Montana State University - Bozeman, College of Agriculture, 2013) Kohlbeck, Katelyn Storey; Chairperson, Graduate Committee: Jane A. BolesTenderness has been identified as one of the most important traits consumers think about when choosing a steak. Unfortunately, the variation and lack of tenderness in steaks has created a negative eating experience for consumers. Recent research has raised the question if temperament as measured by exit velocity and docility scores could be a factor influencing variation in tenderness. However, docility scores are applied subjectively and exit velocity measurements require timers that can be expensive. An objective score that could be used would be helpful. Animals under stress often revert to anaerobic metabolism, especially in the muscle. Anaerobic metabolism results in elevated blood lactate suggesting the use of the small blood lactate meters as objective measures in identifying an animal's response to stress. The objective of this study is to determine if temperament effects growth rate and overall tenderness of beef steaks, and can blood lactate be used as an objective measurement of temperament. One hundred and fifty four steers were evaluated for exit velocity, blood lactate and docility score. Steers were humanely harvested and carcass data obtained. Loins from 30 steers were obtained and cut into steaks. The steaks were aged 3,7,14, and 21 days postmortem and used for shear force, and myofibrillar fragmentation index analysis. All temperament measurements were significantly correlated meaning if average lactate measurement went up the exit speed was high along with the docility score being higher. Temperament and growth classification significantly affected carcass weight. The animals that left the chute more slowly had lower carcass weights than did the steers that left the chute at a fast or medium rate. Additionally, blood lactate significantly affected shear values. Shear was significantly correlated to growth rate, along with blood lactate level. In conclusion temperament did not affect growth rate but did have an impact on tenderness. Our results suggest that growth rate, exit velocity and blood lactate contribute to variation in tenderness. Finally, if an animal is temperamental based on exit scores and lactate concentrations before harvest this could set the stage for postmortem processes that contribute to the high variance in tenderness in the marketplace.