IV. International Agricultural, Biological & Life Science Conference, Edirne, Turkey, 29 - 31 August 2022, vol.4, pp.342-343
Carcass characteristics and meat quality are economically important traits in cattle breeding. Concerning the genotypic background of these phenotypic traits, polygenic inheritance should be taken into consideration and thus multiple genes may have significant effects. Although there are cattle breeds specifically developed for beef production, native breeds and their crosses with culture breeds still have a substantial share in meat production. On the other hand, these native breeds are important constituents of Turkish national biodiversity. Therefore, this study aimed to evaluate the effects of SNPs of bovine Melanocortin-4 receptor (MC4R) and calcium voltage-gated channel auxiliary subunit alpha-2 delta 1 (CACNA2D1) genes on beef yield and quality traits in Turkish native cattle breeds. In this context, a total of 102 bulls including Turkish Grey Steppe (n=28), East Anatolian Red (n=36), Zavot (n=9), and their F1 crossbreds with the Holstein-Friesians (n=29). All animals had the same environmental and feeding conditions. The phenotypic traits measured were slaughter weight, hot carcass weight, chilled carcass weight, dressing percentage, chilling loss, carcass fatness score, carcass pH, and marbling score. DNA was isolated from whole blood by the standard phenol-chloroform–isoamyl alcohol extraction method. In this study, g.59164671G>C polymorphism in the MC4R gene (c.856C>G) and g.38638971A>G polymorphism in the CACNA2D1gene (c.2027A>G) were evaluated (rs108968214 and rs448872602, respectively) by using the PCR-RFLP. The gene and allele frequencies, Hardy–Weinberg equilibrium, gene heterozygosity, polymorphism information content, the effective allele number, the fixation index, the level of possible variability realization, the Shannon-Weaver diversity index were estimated. Association analysis was performed by the least-squares method as applied in a general linear model by selecting statistical models based on the adjusted coefficient of determination values with Tukey’s test as the post-hoc comparison. Results revealed that the GG genotype has a remarkably low frequency in all examined breeds. Polymorphism information content ranged from 0.2446 to 0.3699 and the effective allele number ranged from 1.3931 to 1.9616. The highest gene heterozygosity was observed in Turkish Grey Steppe cattle (0.4898) whereas the highest level of diversity was observed in the Holstein crossbreds (Shannon-Weaver diversity index=1.041). In this study, a novel effect of the g.38638971A>G polymorphism of the bovine CACNA2D1 gene on marbling score (P<0.05). Individuals with the GG genotype had a higher marbling than those with the AA and AG genotypes. There was no significant association between the MC4R genotypes and any of the phenotypic traits analyzed. BTA 24q27 and BTA 4q18, where the MC4R and CACNA2D1 were located, respectively, are close to genomic regions for some crucial QTLs associated with carcass characteristics and meat quality. Hence, novel associations of MC4R and CACNA2D1 genotypes with these traits are not surprising. To the best of our knowledge, this is the first study reporting a possible association with the CACNA2D1 g.38638971A>G genotypes and bovine marbling. Moreover, the breeds studied in this study are the national biological wealth of Turkey and thus the present genetic evaluation may be useful for further research on the corresponding subjects, especially for the bovine CACNA2D1 gene.