Sex-sorted sperm in farm animals: scale of use, the effectiveness of insemination, risk factors

The aim of the study was to present the scale of use, risk factors and possibilities, which sorter semen gives in biotechnics used in reproduction of cattle. Modern sorters allow for the evaluation of 6 million X and Y spermatozoa per hour. Sex-sorted semen, which is commercially used, contains 2.1 x 10(6) of spermatozoa. It is used mostly in AI of milk heifers, mainly in large cattle herds. Sorted semen containing Y spermatozoa is sold less often in the world than the one with X spermatozoa. The percentage of the desired sex of the young is higher than 90. The pregnancy rate after application of sorted semen is about 2025% lower than after insemination of non-sorted semen and depends on a number of factors. The main factors are: breed of female, service number, the herd of origin, the depth of semen deposition, the bull producing semen, ambient temperature and technical parameters during sperm sorting. A number of methods have been developed to improve conception rate, including timed artificial insemination (TAI) and synchronization of heat and ovulation. Results of donor inseminations with the use of sorter semen are presented, with the lower percentage of embryos suitable for the transfer and embryos of the highest quality highlighted. Previous studies do not indicate a reduction of the conception rate after the transfer of embryos obtained in vitro and in vivo after fertilization using sorted semen. It remains difficult to justify a significant increase in the frequency of stillbirths of bulls after using sorted sperm. Similarly, 16% of stillbirths of bulls were observed after embryo transfer, when donors were inseminated with sorter semen. The percentage of stillbirths of bulls after embryo transfer with the use of conventional semen is 9%. The sorted semen is not often used for inseminations in pigs, sheep and goats.