The relationships between κ-casein (CSN3) gene polymorphism and some performance traits in Simmental cattle

Abstract

In this study we aim to examine genotypic structures in terms of the $\kappa$ -casein (CSN3) gene locus in 70 head of Simmental cattle raised in a private enterprise in Erzurum to determine the distribution of genotypes and allele frequencies in cattle in terms of related genes and to correlate the determined genotypes with some performance characteristics. CSN3/HinfI gene polymorphisms were identified in DNA isolated from blood samples taken from Simmental cattle used in the study using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The frequency of the AA, AB, and BB genotype of the CSN3 gene in the population was 57.14 %, 32.86 %, and 10.00 %, respectively; the frequency of the A allele was 0.74; and the frequency of the B allele was 0.26. The mean value for the AA, AB, and BB genotypes was 5151 $\pm$ 308.6, 5805 $\pm$ 370.3, and 5772 $\pm$ 547.3 kg for real milk yield, respectively; 5313 $\pm$ 233.9, 5784 $\pm$ 280.7, and 6458 $\pm$ 414.8 kg in 305 d for milk yield; 17.9 $\pm$ 0.75, 18.6 $\pm$ 0.89, and 19.6 $\pm$ 1.32 kg for daily milk yield; and 294 $\pm$ 13.7, 316 $\pm$ 16.5, and 294 $\pm$ 24.4 d during the lactation period. The distribution of the CSN3 gene locus in the studied population is in genetic equilibrium according to the Hardy-Weinberg principle. The genotype and allele frequencies determined in terms of CSN3 gene polymorphism can be considered sufficient to reveal the genotype diversity of the breed, and it was determined that the relationship of CSN3 genotypes was only significant with 305 d milk yield ( $P<0.05$ ) in terms of the association between CSN3 genotypes and some performance traits. It has been concluded that animals with the CSN3 BB genotype have an economic advantage within the herd and that CSN3 can be used for marker-assisted selection (MAS) in this regard.