PSI-B-22 - Analysis of the development of high-quality corpus luteum of the ovaries in recipient heifers

For effective embryo transplants, it is important to select among the repair heifers recipients with high-quality corpus luteum, corresponding in morphometric parameters to the development of 7-8 days of the estrous cycle. It is known that ipsilateral embryo transplants are more effective than contralateral ones. Therefore, for the effective organization of groups of recipients, it is necessary to have a prognosis for the development of corpus luteum differentially on the left or right ovary. The data on the ratio of these indicators have been insufficiently studied. To resolve this issue, sexually mature repair heifers of the Ukrainian red dairy breed (n = 201) were rectally examined during spontaneous (n = 92) and induced (n = 109) cycles (first time on day 0, again - on 7-8 day). In the group of heifers with a spontaneous cycle, it was found that after ovulation of the follicle on the right ovary, high-quality yellow bodies are formed in 71.4% of individuals, and premature lysis of the yellow bodies was found in 28.6%. On the left ovary, respectively -58.3% and 41.7%. In the induced group of recipients, after ovulation, high-quality yellow bodies were formed on the right ovary in 65.2% of individuals, prematurely lysed yellow bodies - in 34.8%; on the left, respectively - 55.8 and 44.2%.

The study found that the right pair gonad is functionally dominant in repair heifers. In induced cycles, premature lysis of the corpus luteum (more by 6.28%; P < 0.001) occurs more often than spontaneous ones. The data obtained reveal the morphological and functional patterns of development of high-quality corpus luteum of the ovaries, the presence of which undoubtedly increases the level of engraftment of preimplantation embryos in cattle.