REPEATED SUPEROVULATIONS IN HIGH-YIELDING COWS

The results of superovulation were processed in 25 donors with the total number of 106 lavages, out of which 89.6% were successful. The average number of superovulations per donor was 4.24 (ranging from 1 to 11); the average number of all recovered embryos made 6.15 (s(x) = 5.01) and the average number of transferable embryos was 4.39 (s(x) = 4.28). The number of recovered embryos and embryo quality did not change with respect to the order of superovulation repetition. The best results were recorded in the third superovulation (xBAR = 5.51 of transferable embryos). Considering the evaluated effects on the number of recovered and transferable embryos, these were positive: calving to superovulation interval of 200 to 299 days (xBAR = 5.67 embryos), 89-day interval from preceding lavage (xBAR = 5.33 embryos), November to April as the months of winter feeding season (xBAR = 4.22 to 6.10 embryos), and the genotype of the cows of Bohemian Pied breed (xBAR = 4.93 embryos) as compared with the donors of Black-Pied breed (xBAR = 4.33 embryos). But the effects of all evaluated factors were statistically insignificant (P > 0.05) due to high variability. Of the total number of 306 embryotransfers, 56.2% of cows got in calf; following E. T. of fresh embryos, 60.5% of cows got in calf. There were recorded 8.75 pregnant recipients per donor (ranging from 0 to 24).