THE INFLUENCE OF GENETIC VARIANTS OF κ-CASEIN ON MILK COMPONENTS

Abstract

Milk production of 22 cows of Slovak Pied breed with Holstein-Friesian was analyzed according to the genetic variants of the polymorphic proteins determined by starch gel electrophoresis. The effect of genetic variants of the proteins was analyzed by selected properties of milk (milk yield, proteins, fats and lactose). Differences between the productive characters in testing groups were evaluated according to statistic method of t-test. Evaluation was carried out during throughout lactation. Based on the analyses we have obtained results frequency of genotypes: κ-CN AA in 9 cows (41%), AB in 12 cows (54.5%) and BB in one cow, which is 4.5%. The average daily milk production of κ-CN AA was 13.5 l/day and in κ-CN AB 14.2 l/day. Contents of protein of genetic variation κ-CN AA was 3.1% in milk genotype κ-CN AB was found not significant lower protein proportion 3.0%. Based on the analyses, we can assume that cow’s nutrition higher influence the increase in the proportion of protein than polymorphism of κ-CN. In our research was found out the average fat content 4.0% in genetic variation of κ-CN AA and not significant lower in genetic variation κ-CN AB 3.8%. The average lactose content in the cow’s milk with κ-CN AA genotype was 4.9% and κ-CN AB was 5.0%. The difference between fat content wasn’t statistically significant.