Authors : A. K?bek , J. itn? , J. Bujko and A. Trakovick
Abstract: The genetic structure of polymorphic milk proteins in alphas1-casein, beta-lactoglobulin, beta-casein and kapa-casein systems were analysed by the method of starch gel electrophoresis. The homozygotic and heterozygotic genotype combinations of dairy cows of Slovak spotted breed (n=345) were evaluated for dairy parameters. Data used in protein index calculation were obtained from lactation records of 1250 standardized lactations. 1. In polymorphism alpha s 1-casein with genetic variant BC highly significance has occurred (++P=0,01) in milk production on the first lactations 719 kg (BC>BB) and in beta-lactoglobulin system within second and following lactations 150,6 kg of milk (AB>AA+BB, +P=0,01). 2. Protein content (kg) tested between groups of heterozygote and homozygote genotypes of polymorphic milk protein was significantly higher (+P=0,01) by 5,4 kg on second and following lactations in group of AB genotypes of beta-lactoglobulin (AB>AA+BB). 3. Within first lactations significantly high difference of 28 kg of fat has occurred between genotypes BC and BB of alpha s1-casein (++P=0,01, BC>BB). The paper is reporting also index of protein production , which is on the first lactations 116,7%, on second and following lactations 105,9% and over all lactations 107%. Selection criteria used in index of protein production calculated for first calved cows as well as for cows of Slovak spotted breed are listed in section Material and methodology.
A. K?bek , J. itn? , J. Bujko and A. Trakovick , 2003. Genetic Variants of Milk Proteins and Indexes of Milk Performance Dairy Cows of Slovak Spotted Breed on Different Lactations . Journal of Animal and Veterinary Advances, 2: 519-523.