Master of Science (MS)
Animal Science (Animal, Dairy, and Poultry Sciences)
The first objective of the two studies in the research herein was to evaluate growth, performance and carcass quality and composition traits from a group of spring born calves sired by Charolais, Braunvieh, or Simmental bulls. Growth traits analyzed included birth weight (BW), weaning weight (WW), and hip height (HH). Carcass quality and composition traits analyzed included hot carcass weight (HCW), rib eye area (REA), back fat thickness (BF), marbling score (MS), and yield grade (YG). Analysis revealed Simmental sired calves were significantly heavier (P<.05) at birth when compared to Charolais and Braunvieh sired calves. Braunvieh sired calves were reported to be significantly (P<.05) shorter than Simmental sired calves for hip height. Hot carcass weight analysis revealed that Charolais sired calves were significantly (P<.05) heavier when compared to Braunvieh sired calves. No individual sire breed group displayed any significant differences for weaning weight, rib eye area, back fat thickness, marbling score, or yield grade. The second objective was evaluate potential SNP associations on four candidate genes with growth, performance, and carcass composition traits in a population of crossbred steers sired by Charolais, Braunvieh, and Simmental bulls. Traits analyzed for growth, performance, and carcass traits were previously mentioned. Analysis was performed on 38 steer calves. Single nucleotide polymorphisms within four candidate genes including Thyroglobulin (TG), Adiponectin (ADPOQ), Insulin like growth factor-1 (IGF-1), and Calpastatin (CAST) were chosen for analysis. A total of 14 SNP on TG, ADPOQ, CAST, and IGF-1 genes were significantly associated with birth weight and weaning weight. Analysis revealed 13 SNP on TG, ADPOQ, IGF-1, and CAST genes significantly associated (P<.05) with HCW, BF, MS, and YG. No markers were reported to be significantly associated (P<.05) with HH or REA. A total of 11 markers with 3 markers located on the ADPOQ gene, 1 marker located on the IGF-1 gene, 3 markers located on the TG gene, and 5 markers located on the CAST gene were significantly associated with both growth and carcass traits.
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Mizell, Malcolm Seth, "A quantitative and molecular evaluation of calves sired by three different breeds for growth, performance, and carcass traits" (2014). LSU Master's Theses. 3181.