FERTILITY IN HEIFERS OF SLOVAKIAN PIED BR EED, BLACK-AND-WHITE BREED AND THEIR CROSSES

A total of 7 300 heifers of the Slovakian Pied breed, holsteinised Bla ck and White breed and their crosses with different genetic share were analysed by LSM method. The fixed effects of herd, year of the 1st in semination, genotype group and age at Ist insemination as a covariate were included into models of analysis of covariance. The service perio d, number of inseminations, conception rate and gestation length were dependent variables. Tab. I shows the estimates of mean values of the particular breeds and genotype groups of crosses. Service period, numb er of inseminations and gestation length were longer in Slovakian Pied heifers. Conception rate was higher in Holstein heifers and crosses a nd differences were statistically highly significant (P < 0.01). Tabs. II and III show the results of analyses of covariances. The factors h erd and year participated in variability of all investigated parameter s statistically highly significantly (P < 0.01). The effect of genotyp e group in the crosses Was not statistically significant. Age at Ist i nsemination statistically significantly influenced observed traits onl y in the black and white population.