Associations Between IGF-II Gene Polymorphism and Milk Yield Characteristics In Brown Swiss Cattle

Abstract

This study was carried out on 114 Brown Swiss cattle reared in intensive conditions at Ataturk University Food and Livestock Application and Research Center and at the private cattle farm found in Erzurum province. Genotypic structures were examined in terms of Insulin-like growth factor (IGF)-II gene locus and the distribution of genotypes and allele frequencies of the cattle concerning the genes were determined. The identified Insulin-like growth factor (IGF)-II genotypes were associated with milk yield traits such as actual milk yield, 305-day, and daily milk yield. Insulin-like growth factor (IGF)-II genotypes were determined by using the Polymerase Chain Reaction (PCR)- Restriction fragment length polymorphism (RFLP) method from blood samples taken from the cattle. The CC, CT, and TT genotype frequencies of the Insulin-like growth factor (IGF)-II gene found in the population were 41 (34%), 65 (54%), and 14 (12%), and the frequency of the C allele and the T allele was found to be 0.61 and to be 0.39. The general averages of actual true milk yield, 305-day and daily milk yield were 4317±272.9 kg, 5277±240.7 kg and 18±0.9 kg, respectively, while CC, CT and TT genotypes 4168±515.8, 3756±321.7 and 5382±600.3 kg, respectively. As a result, correctly identified IGF-II genotypes were detected by using the PCR-RFLP method in the blood samples obtained from Brown Swiss cattle. Genotype and allele frequencies determined for IGF-II gene polymorphism can be considered sufficient to demonstrate the genotype diversity of the race. According to the Hardy-Weinberg genetic equilibrium test, the distribution of genotype frequencies of the cattle was observed in equilibrium.