title: Association of a single nucleotide polymorphism in the calpastatin gene with carcass and meat quality traits of beef cattle.
abstract: Calpastatin (CAST) is a naturally occurring protein that inhibits the normal tenderization of meat as it ages postmortem. A SNP was identified in the CAST gene (a G to C substitution) and genotyped on crossbred commercially fed heifers (n = 163), steers (n = 226), and bulls (n = 61) from beef feedlots, and steers (n = 178) from a University of Guelph feeding trial. The association of the CAST SNP with carcass and meat quality traits was studied. Carcass traits included fat, lean, and bone yield; grade fat; LM area; and HCW. Meat quality traits included marbling grade; i.m. fat content of LM; tenderness evaluation of LM (Warner-Bratzler shear force) at 2, 7, 14, and 21 d of postmortem aging; and tenderness evaluation of semitendinosus muscle at 7 d of postmortem aging. The mixed model used in the analyses included fixed effects of CAST genotype, sex, slaughter group, and breed composition (linear covariate); sire was a random effect. For the analysis of shear force, i.m. fat content of LM was also included in the model as a linear covariate. Shear force measures were analyzed within days of postmortem aging and by repeated measures analysis. The CAST SNP allele C was more frequent (63%) in the crossbred population than allele G. The CAST SNP was associated with shear force across days of postmortem aging (P = 0.005); genotype CC yielded beef that was more tender than GG (-0.32 kg +/- 0.13), and CG had intermediate tenderness. The corresponding average allele substitution effect (G to C substitution) was also highly significant (-0.15 +/- 0.05 kg, P = 0.002). A lower percentage of unacceptably tough steaks (shear force > 5.7 kg) at 2 and 7 d postmortem was associated with an increasing number of C alleles (P < or = 0.05). At 7 d postmortem, the percentage of unacceptably tough steaks decreased by 24 and 35%, respectively, for animals carrying 1 and 2 copies of the C allele relative to animals with no C alleles. However, genotype CC had a greater fat yield (+1.44 +/- 0.56%; P = 0.037) than genotype GG, with a corresponding allele substitution effect of 0.67 +/- 0.27% (P = 0.015). Therefore, the CAST SNP allele C was associated with increased LM tenderness across days of postmortem aging and, importantly for the beef industry, had a significant reduction in the percentage of steaks rated unacceptably tough by consumers based on an assumed threshold level.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Ontario, N1G-2W1, Canada. Schenkel@uoguelph.ca
authors.forename: F S
authors.initials: FS
authors.lastname: Schenkel
authors.forename: S P
authors.initials: SP
authors.lastname: Miller
authors.forename: Z
authors.initials: Z
authors.lastname: Jiang
authors.forename: I B
authors.initials: IB
authors.lastname: Mandell
authors.forename: X
authors.initials: X
authors.lastname: Ye
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: J W
authors.initials: JW
authors.lastname: Wilton
mesh_terms: D000818:Animals; D001823:Body Composition / Q000235:genetics*; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002417:Cattle / Q000033:anatomy & histology* / Q000235:genetics; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D008297:Male; D008460:Meat / Q000592:standards*; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide / Q000235:genetics / Q000502:physiology*; D013997:Time Factors
chemical_list: D002135:Calcium-Binding Proteins; D017931:DNA Primers; C033668:calpastatin