Relations between genetic variants of Κ-casein and ß-lactoglobulin and Performance of Black and White and Polish Red cattle

Abstract

Performance of 184 cows from 4 herds of Black and White (SR) and 178 cows from 4 herds of Polish Red breed (RP) was compared due to genotype encoding milk proteins: κ-casein and ß-lactoglobulin. Frequence of inividual genotypes differend significantly both between herds within the breed. Statistically significant influence of genotype was found in relation to milk fat content in SR cattle (κ-CN AA > κ-CN BB and ß-LG BB >ß-LG AB > ß-LG AA ) and in RP cattle milk protein yield (κ-CN BB > κ-CN AA ) and fat content (ß-LG AA > ß-LG AB and ß-LG ). The highest protein content and protein yield in milk was found in cows of both breeds carrying KCNBB genotype (P>0.05). Significant relation with the age of first calving was stated in SR cows: κ-CN AA > Κ-CN AB , in RP cows κ-CN BB > κ-CN AB and in SR cows ß-LGBB >ß-LG AB . Other traits such as longevity, life-time number of calvings and lactations, life-time yield were not found significantly related to searched genotypes although some trends were observed.