Association of the muscle hypertrophy locus with carcass traits in beef cattle.

Abstract

A locus near the centromere of bovine chromosome 2 is responsible for muscle hypertrophy (mh) in cattle. The objectives of this study were to refine the genomic region in which the locus resides and to assess the effects of a single copy of the mh allele on carcass and birth traits. Two half-sib families were developed using a Belgian Blue x MARC III (n = 246) or a Piedmontese x Angus (n = 209) sire. Traits analyzed were calving ease (CE), birth weight (BWT, kg), longissimus rib eye area (REA), retail product yield (RPYD), USDA yield grade (YG), marbling (MAR), fat thickness (FAT), estimated kidney, pelvic, and heart fat (KPH), and longissimus tenderness measured as Warner-Bratzler shear force at 3 (S3) and 14 (S14) d postmortem. Six microsatellites were used to determine the presence or absence of the mh allele and to confirm the location of the locus affecting the traits, which was assessed to be 4 cM from the beginning of the linkage group, with the 95% confidence interval between 2 and 6 cM. Cattle with an mh allele had increased (P < .01) REA, RPYD, and BWT and decreased MAR, YG, FAT, and KPH, compared with those without the allele. The effects of the mh allele (mh/+ vs +/+) were 1.35, 1.6, .41, -1.01, -1.42, -.84, and -.86 residual standard deviations, respectively. There were no effects (P > .10) for CE, S3, and S14. Allelic differences due to the mh locus were similar for both sources (Belgian Blue or Piedmontese). Individuals inheriting a single mh allele had a leaner, more heavily muscled carcass compared with those inheriting the alternative allele. Thus, mating schemes that maximize production of mh/+ genotypes provide a viable approach for improving carcass composition.

Muscle-related traits in�cattle: The role of the myostatin gene in the South Devon breed

“…The present study looked at predictors of carcass quality in all three genotypes, unlike the study of Casas et al [4] where more detailed carcass traits were only measured in +/+ and del11/+ animals. Our study suggests that the del11 allele has additive effects on muscling score and fat depth.…”

“…[12,13,17,19,21]; also reviewed by Arthur [3]); and (ii) results of studies where crossbred animals were directly genotyped [4,5]. While such studies act as benchmarks for the current study, the results of both sets need to be confirmed for a single population with a segregating del11 allele.…”

“…Our study suggests that the del11 allele has additive effects on muscling score and fat depth. Casas et al [4] found the heterozygote to have greater muscle area (longissimus rib eye) and retail yield, but decreased marbling, yield grade and carcass fat measures. The results for the comparison of the heterozygote and wild type for these traits are similar in our study and theirs.…”

“…Therefore, the key information required is the way in which the del11 allele affects traits of economic importance. There is information available in the literature on the effects of double muscling on weight [4,5,19], muscling [4,21] and calving difficulty [5]. However, this information is limited in two ways.…”

Haplotype diversity of the myostatin gene among beef cattle breeds

“…Given the high influence of the myostatin gene in the good muscular conformation of most European bovine beef breeds, and although there have been many efforts to identify other influencing genes and QTLs with smaller effects [5][6][7]35], it seems necessary to systematically screen most individuals in order to allow the management of this particular locus, and to possibly evaluate the effect of this and other genes in the phenotype.…”