Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2011
Publication Date: 4/1/2012
Citation: Rempel, L.A., Casas, E., Shackelford, S.D., Wheeler, T.L. 2012. Relationship of polymorphisms within metabolic genes and carcass traits in crossbred beef cattle. Journal of Animal Science. 90(4):1311-1316.
Interpretive Summary: Carcass and meat quality characteristics such as marbling, flavor, and tenderness rely heavily upon fatness traits. The basis of the current study was to investigate the association of mutations (single nucleotide polymorphisms; SNP) within select genes that directly or indirectly affect fat mechanisms against carcass and growth traits in crossbred cattle. Informative SNP from the genes; cocaine- and amphetamine-regulated transcript (CART), DNA-protein kinase (DNA-PK), fatty acid synthase (FASN), and fat mass and obesity associated (FTO) were genotyped and association analyses were performed. SNP from CART, FASN, and FTO were associated with growth traits including harvest weight, average daily gain, and hot carcass weight whereas SNP from DNA-PK associated with marbling score and fat thickness as well as with percent choice, yield grade, and retail product yield. These data provide evidence for a possible relationship, directly or indirectly, between the tested genes and fatness traits that impact growth and/or carcass quality. The tested SNP could be utilized for marker assisted selection or marker assisted management systems supporting more efficient and economical cattle production practices.
Technical Abstract: Feed intake has been shown to alter neurological signaling related to feeding behavior and subsequent activation of adipogenic mechanisms. Fat characteristics are pivotal for carcass and meat quality, including marbling score, flavor, and tenderness. The objective of this study was to establish the association of SNP, from genes functionally related to fat metabolism and obesity, with growth, fat, and carcass traits in steers. A total of 33 informative SNP from candidate genes [cocaine- and amphetamine-regulated transcript (CART), DNA-protein kinase (DNA-PK), fatty acid synthase (FASN), and fat mass and obesity associated (FTO)] were used to genotype crossbred steers (n = 620), and associations with growth and carcass traits were assessed. Five markers within the DNA-PK gene were associated (P < 0.05) with fat thickness. One of these SNP was also associated (P < 0.05) with percent choice, yield grade, and retail product yield. Additionally, two unique DNA-PK SNP were associated (P < 0.05) with marbling score. Three haplotypes were observed using these SNP and were significantly (P = 0.0014) associated with marbling score. Harvest weight, average daily gain, and hot carcass weight were associated (P < 0.05) with SNP from CART, FTO, and FASN. Data from this study indicate that polymorphisms within candidate genes have an indirect relationship with lipogenesis. Replication of these results within other populations will be necessary to establish if these markers will be successful as predictors of fatness components and carcass traits in cattle.