MILK PERFORMANCE OF CROSSBRED COWS OF THE SLOVAK PIED BREED WITH DAIRY BREEDS

A total of 15,814 lactations of the cows of the Slovak Pied cattle and crossbred cows of this breed with dairy breeds which calved in 1983-1 991 were evaluated in this paper. The least-squares method was used fo r statistical analysis. The effects of herd and calving year and the e ffects of genotype group and year x genotype group interaction in the crossbreds were included in models of analysis of covariances. Lactati on days and age at first calving in the first-calves and lactation num ber in the cows were concomitant variables. Milk production per lactat ion, fat percentage in milk and fat production per lactation were depe ndent variables. Tabs. I and II show the basic variation-statistical d ata on the investigated parameters. The crossbreds of all the investig ated hereditary blood shares are evaluated in total. Milk production o f this group was higher by 10% and/or 9% in the 1st, 2nd and other lac tations in comparison with the Slovak Pied dairy cows. Tabs. III to IV show the results of analyses of covariances. The factors herd and yea r participated in variability of all the investigated parameters stati stically highly significantly (P < 0.01). The effect of genotype group in the crossbreds was statistically highly significant (P < 0.01) for milk and fat production and insignificant for fat percentage. Lactati on days had a statistically highly significant (P < 0.01) effect on va riability of milk and fat production, but they did not influence fat p ercentage in milk statistically significantly. Age at 1st calving stat istically significantly influenced milk and fat production in 1st lact ation in the crossbreds, and fat percentage and production in the pure first-calvers. The effect of lactation number on variability of milk and fat production was statistically highly significant (P < 0.01) in both investigated groups. Tabs. VII and VIII show the estimates of mea n values of the particular genotype groups. Milk production in 1st lac tation was higher by 170-460 kg in the crossbreds, depending upon the blood share of dairy breed. In second and other lactations the differe nces were 135 to 355 kg milk in favor of the crossbreds. All differenc es from the Slovak Pied breed were statistically highly significant (P < 0.01). The crossbreds of all groups had the lower fat percentage in milk.