Milk protein genotypes and their association with milk composition traits in the Lithuanian dairy cattle

Manufacturing properties of milk are related to milk protein polymorphism. Alfas1-CN-casein, kappa-CN-casein and beta-LG-lacto globulin genetic variants of bovine milk proteins were studied in two native cattle breeds – Lithuanian Light Grey (LLG) and Lithuanian White Backed (LWB) and two modern cattle breeds – Lithuanian Black & White (LBW) and Lithuanian Red (LR) using the polymerase chain reaction (PCR). The results confirmed that Lithuanian cattle breeds have the same variants of milk protein systems most common for dairy milk-yielding European cattle. The only exception was the Lithuanian Red cattle breed which had the highest frequency of kappa-CN B allele and beta-LG B allele – both of which are most favorable for milk manufacturing. The alfas1-CN allele C, kappa-CN allele B and beta-LG allele B were superior in milk protein content, while alfas1-CN allele B and kappa-CN allele A were superior in milk yield. Kappa-CN E allele had a positive effect on milk fat. Beta-LG allele B had a positive effect on lower somatic cell count. The identification of kappa-CN and beta-LG genotypes could be an economically important selection criteria for dairy herds designated for industrial milk production. In addition, milk protein polymorphism may be used as selection criteria and informative molecular markers for yield, composition and technological properties of milk in cattle selection programs.