The objective of this study was to evaluate the in vitro fertility of sexed (SX) vs. non-sexed (NS), frozen-thawed bovine semen from two Holstein bull, from the same batch each one. Offspring sexing represents an important advance for livestock production. Flow cytometry separates X and Y spermatozoa by difference in DNA (4 % greater in X) with 90 % effectiveness. Cumulus-oocytes complexes (COC) were obtained from follicles measuring between 2 and 8 mm collected from slaughterhouse ovaries; they were then cultured 22 h for maturation in TCM-199 + 5 % BFS + 10 % bovine follicular fluid (BFF) in 100 μl drops with mineral oil, in incubator (38.5 oC, 5% CO and 95 % humidity). Postmaturation, 4 groups were randomly formed and inseminated with 2 NS and SX of the 1 and 2 bulls, including them in 100 μl drops at 10 COC per drop of capacitated semen diluted to a concentration of 2x106 sperms/ml in all groups, incubated during 6 h. They were then cultured in CR1aa + 5% BFS in an incubator. At 48 h cleavage and at day 7 embryonic development, were assessed. Results were analyzed with χ2 square Test. There were significant differences (P<0.05) in the embryonic development in bull 1, grater in NS. In bull 2 there were not significant differences in cleavage neither in embryo development.
KEY WORDS: Sex sorted sperm; In vitro fertilization; Bovine; Embryos.