The influence of kappa casein protein polymorphism on milk production traits and other productive performance traits of brown-swiss cattle

Polymorphism of kappa casein protein (ê-casein) in total 113 brown-swiss cattle was investigated using horizontal starch-urea gel electrophoresis method to verify its effect on milk production traits (actual milk yield,305 d milk yield,actual fat yield,305 d fat yield,fat percentage and lactation length) and influence of other factors such as parity and season of calving; aiming at utilizing it as a genetic aid in selection to improve the milk production traits of this breed. the allelice frequencies of a,b,and c were found to be 0.345,0.633,and 0.022 respectively. genotype frequencies were in accordance with the hardy-weinberg equilibrium. general linear model (glm) was used to analyze differences between genotypes. the results indicated that κ-casein genotypes significantly (p<0.05) affected 305 d milk yield,actual fat yield,305 d fat yield,fat percentage,and lactation length. but it had no effect on actual milk yield. parity and season of calving had effect (p<0.05) on milk production traits. this study indicated that the ê-casein genetic variants may be used as a genetic aid through increasing the frequency of desired genotypes to improve the milk production traits of this breed. copyright 2015 zoological society of pakistan.