THE LEVEL OF MILK PERFORMANCE AND FERTILI TY IN SOME ELITE HERDS OF CZECH PIED CATTLE

The paper deals with an assessment of the effect of milk performance o f dairy cows in elite herds on some fertility parameters. Significantl y higher milk performance and fat production (P < 0.01) were recorded in CA 50 genotype than in the other investigated genotypes. Fertility parameters tended to have insignificantly better results in the genoty pes with the higher share of the Bohemian Pied breed (P > 0.05). Insem ination index tended to increase with the number of lactation. Milk pr oduction and fat production increased with the number of lactation (P < 0.1, P > 0.05). Milk production per lactation was insignificantly in creasing with the growing age at first calving (P > 0.05). The value o f insemination index was highest ((x) over bar = 2.06 +/- 1.20) in the group of breeding cows which calved down at the age above 29.6 months , which was highly statistically significantly more than in the other groups (P < 0.01) in which the value of insemination index ranged from 1.55 to 1.76. Dairy cows with performance by 5,280 kg milk per lactat ion had the significantly lower values of insemination index and short er calving intervals (P < 0.01). A similar significant relation was de termined with respect to fat production. The cows with born twins had significantly higher milk and fat production (P < 0.05) in comparison to the cows with born single calves. Processing of the determined data under investigation by linear model revealed a significant effect of herd (P < 0.05), age at first calving (P = 0.0001), fat production per lactation (P < 0.05) and lactation number (P < 0.01) on the values of insemination index. No statistically significant effect was determine d from assessment of the relation to calving interval (P > 0.05). Some antagonistic relations between the parameters of milk production and fertility have been observed.