Scholarly Work - Animal & Range Sciences
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8931
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Item Molecular Pathways for Muscle and Adipose Tissue Are Altered between Beef Steers Classed as Choice or Standard(MDPI AG, 2023-06) Haderlie, Sarah A.; Hieber, Jordan K.; Boles, Jane A.; Berardinelli, Berardinelli; Thomson, Jennifer M.Targets for finished livestock are often determined by expected fat, either subcutaneous or intramuscular. These targets are used frequently to improve eating quality. Lower intramuscular fat, lack of product uniformity, and insufficient tenderness can negatively impact beef acceptability. This study aimed to investigate the differences in gene expression that alter metabolism and intercellular signaling in the muscle and adipose tissue in beef carcasses at different fat endpoints. In this study, longissimus thoracis muscle samples and adipose tissue were collected at harvest, and RNA was extracted and then sequenced using RNAseq. Differential expression was determined using edgeR, and p-values were adjusted using the Benjamini–Hochberg method. A corrected p-value of 0.005 and log2 (fold change) of >1 were the threshold to identify differential expression. Comparison between intermuscular and subcutaneous fat showed no differences in the genes activated in the two adipose tissue depots, suggesting that subcutaneous fat was an adequate sample. Carcass data allowed the classification of carcasses by USDA quality grades (marbling targets). In comparing muscle from Standard and Choice carcasses, 15 genes were downregulated, and 20 were upregulated. There were 49 downregulated and 113 upregulated genes comparing adipose tissue from Standard and Choice carcasses. These genes are related to the metabolism of fat and energy. This indicates that muscle transcript expression varies less than adipose. In addition, subcutaneous fat can be used to evaluate transcript changes in fat. However, it is unclear whether these fat tissues can be used as surrogates for marbling.Item Identification of Genomic Regions for Carcass Quality Traits within the American Simmental Association Carcass Merit Program(MDPI, 2021-02) Hieber, Jordan K.; Endecott, Rachel L.; Boles, Jane A.; Thomson, Jennifer M.USDA quality and yield grade are primary driving forces for carcass value in the United States. Carcass improvements can be achieved by making selection decisions based on the results of genetic evaluations in the form of expected progeny differences (EPD), real-time ultrasound imaging, and physical evaluation of candidate breeding animals. In an effort to advance their ability to accurately predict the breeding value of potential sires for carcass traits, the American Simmental Association launched the Carcass Merit Program as a means to collect progeny sire group carcass information. All records were extracted from the American Simmental Association database. Progeny data were organized by sire family and progeny performance phenotypes were constructed. Sire genotypes were filtered, and a multi-locus mixed linear model was used to perform an association analysis on the genotype data, while correcting for cryptic relatedness and pedigree structure. Three chromosomes were found to have genome-wide significance and this conservative approach identified putative QTL in those regions. Three hundred ninety-three novel regions were identified across all traits, as well as 290 novel positional candidate genes. Correlations between carcass characteristics and maternal traits were less unfavorable than those previously reported.