Effect of Semen on the Embryo Productivity of Donor Cows and the Development of Transplant Calves

In animal husbandry, more heifers are requiredfor the expanded reproduction of the herd or milk, and more bulls are needed toobtain meat. One of the effective ways to artificially regulate the secondary(at birth) sex ratio is the technology of sexed semen. In this connection, thepurpose of this study was to study the effect of sexed and native semen on theembryonic productivity of donor cows, the survival rate of embryos in recipientcows, and the development of transplant calves. The studies were carried out onSimmental cows in the period from 2017 to 2019 in the Galitskoe LLP and PobedaLLP in the Pavlodar region (Republic of Kazakhstan). It was found that 80(78.4%) of 102 embryos were suitable for transplantation in cows fertilizedwith native sperm and 31 of 51 embryos (60.8%) in cows inseminated with sexedsperm. At the same time, embryos at the stage of compact morula and earlyblastocyst prevailed in both groups of cows. Later, at the time of embryotransplantation to recipient cows, the survival rate was 59.5% for two-sex and58.3% for single-sex transplants. During the analysis of postnatal developmentof different-sex transplant calves, it was found that although they werecharacterized by different growth dynamics depending on sex, they generallyexceeded the calves of the control group in this parameter. The detecteddifferences in superovulation and embryo productivity of cows of the Simmentalbreed show that the individual characteristics of donor cows are decisiveregardless of which sperm (native or sexed) was used for artificialinsemination. At the same time, in all cases, donor cows fertilized with nativesemen were distinguished by the best embryo productivity, although thedifferences with cows inseminated with sexed sperm were not significant.