THE INFLUENCE OF KAPPA-CASEIN (CSN3) GENOTYPE ON MILK PRODUCTIVITY IN LACTATION

The purpose of the research was to analyze kappa-casein (CSN3) genotype influence on milk productivity and quality in recordings of 305-days lactation. Data were collected from 55 Latvian Brown genetic resources (LBGR) dairy cows. The blood samples for kappa-casein genotyping of tri-allelic genetic locus (A, B, E) were analyzed in Scientific Laboratory of Biotechnology of Latvia University of Agriculture. Data about milk productivity traits were collected from the Agricultural Data Centre of Republic of Latvia. Significantly highest milk yield was observed in multiparous group (p<0.05), but genotypes of kappa-casein did not affect milk yield significantly. The highest milk yield was obtained from kappa-casein AA genotype. Fat content was significantly different in the last three recordings (p<0.05), but protein content was higher for cows with kappa-casein AB genotype, and lower in groups with BB genotype (p<0.05). The highest somatic cell score was obtained in BB genotype group and multiparous group. B allele had a positive influence on milk composition. kappa-casein allele E was not detected in this group of LB cows.