EFFICIENCY OF TRANSFER OF EMBRYOS OBTAINED DEPENDING ON THE CATEGORY OF DONOR AND BULL, USED FOR INSEMINATION

One of the objectives of embryo transfer is to reproduce the offspring of outstanding parents in order to select among them and subsequently reproduce offspring of even higher quality. The presented material contains the results of research on the influence of the category of donor (cow or heifer) and stud bull on the efficiency of embryo transfer. It was found that the survival rate of embryos obtained from cows and heifers was practically the same and amounted to 51.7 and 50%, respectively. In contrast to cows, in which the pregnancy rate did not depend on the side of transfer, embryo transfer in heifers was more effective when transferred to the right horn compared to the left one by 16.6 p.p. The survival rate of embryos at the morula stage from cows was 4.7 p.p. higher when transferred to the left horn, while in heifers it was 14.7 p.p. higher in the right horn. The survival rate of blastocysts obtained from both cows and heifers was higher when transferred to the right horn. The survival rate of embryos decreased as their quality declined, regardless of either the donor or the horn into which they were transferred. Overall, pregnancy rates ranged from 20 to 80% depending on the bull. There was quite a high variability in the survival rate of embryos from donors inseminated by the same bulls. 

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