7TH NATIONAL – 3RD INTERNATIONAL HERD HEALTH AND MANAGEMENT, Antalya, Turkey, 20 - 23 October 2022, vol.7, no.24, pp.232-233
Myogenic Differentiation 1 (MYOD1), Oxidized Low-density Lipoprotein Receptor 1 (OLR1),
and Melanocortin 4 Receptor (MC4R) genes play important roles in the regulation of the fat and energy
metabolism and physiology of cattle growth as well as health traits. Thus, the variation in these genes
is highly valuable for the improvement of beef yield and quality. This study was designed to evaluate
the effects of the MYOD1, OLR1, and MC4R gene polymorphisms on the selected beef production traits.
A total of 165 Aberdeen Angus bulls and crossbreds were genotyped by PCR-RFLP in this study. We
analyzed the association of the SNPs with slaughter weight, hot and chilled carcass weight, chilling
loss, dressing percentage, back fat thickness, carcass fatness score, color score, and marbling. The
genetic merit for the selected beef yield and quality traits were quantified by the general linear model
(GLM). First, individual gene effects were evaluated. We next analyzed the genotypic interactions for
each phenotypic trait regarding haplotype effects. The genotypic/allelic frequencies and Hardy-
Weinberg Equilibrium was estimated and population genetics parameters including heterozygosity,
number of effective alleles, polymorphism information content, and fixation index were calculated.
Results revealed that all three genotypes were observed for all of the markers. The OLR1 marker was
significantly associated with hot carcass weight (P<0.05) and back fat thickness (P<0.001). Moreover,
the effect of MYOD1 on the beef color score was found to be significant (P<0.05). Significant genotypic
interactions were observed for the MYOD1×OLR1 (back fat thickness and color score) and
OLR1×MC4R (back fat thickness). In addition, some tendencies (P<0.1) were observed at both
individual genotype and haplotype levels. Consequently, novel associations identified in this study may
be useful for the molecular genetic applications incorporated into cattle breeding programs to improve
beef yield and quality.