COMPARISON OF FERTILITY TRAITS OF SLOVAKI AN PIED BREED, BLACK-AND-WHITE BREED AND THEIR CROSSES

Fertility traits are compared in cows of Slovakian Pied breed, holstei nized Black and White breed and their crosses from combination and abs orptive crossing. A total of 10,896 records from the 1st to the 3rd la ctations were analyzed by the least-squares method. A model of analysi s of covariances contained the fixed effects herd, year of calving, ge notype group (Slovakian Pied breed was analyzed without this effect), and concomitant variables milk production over 305-day current lactati on and duration of insemination interval (the indicators insemination interval, days open and calving interval without this variable). The w orst values of fertility traits were determined in the Ist lactation ( Tab. I). Slovakian Pied dairy cows had a statistically highly signific antly shorter days open in all lactations (P < 0.01) in comparison wit h Holstein cows (by 12.5; 15 and 13 days for lactation number 1 to 3). The Slovak breed had a statistically highly significantly (P < 0.01) longer period of pregnancy (according to lactation number by 5.3; 7.2 and 5 days). The genotype groups of the Black and White cattle (crosse s with different blood proportions of the Slovakian Pied and Holstein breeds) showed smaller differences in the indicators, and except the l ength of service period in the second lactation and the calving they w ere insignificant.