Evaluation of milk production of dairy cows of the Slovak spotted breed according to selection for longevity and genetic variants of polymorphic proteins in milk

Milk performance of 681 cows of Slovak spotted breed was evaluated according to the genetic variants of the polymorphic proteins determined by starch gel electrophoresis. In the work the effect of genetic variants of the proteins was analysed on selected performance (production milk in kg, proteins in % and kg). Differences between the productive characters in testing groups were evaluated according to statistic method of Student t-test. Evaluation of performance was done during productive period between 25 - 162 months. The calculation between groups of homozygotes (sum AA+ BB + CC genotypes) and heterozygotes (sum AB+AC+BC genotypes) in the system of beta - casein showed a statistically significant difference (+++P=0,001), (table 1, 2) in milk production (183,7 kg) and proteins production (7,6 kg). In the systems of alpha s1 - casein, beta - lactoglobulin and kapa - casein polymorphisms, the differencies between the testing groups of homozygotes and heterozygotes were not statistically significant (-P