Assessment of swim-up and discontinuous density gradient in sperm sex preselection for bovine embryo production

The purpose of this work was to associate the modified swim-up method with centrifugation in density gradient for the separation of X-bearing spermatozoa. Sperm viability and integrity were evaluated through the Trypan Blue/Giemsa staining method. Quality control of centrifuged spermatozoa was performed in in vitro produced embryos. The results were validated by the sex ratio of in vitro produced embryos using PCR by Y- specific sequences present in bovine male genomic DNA. After determining genetic sex of in vitro produced embryos, the results showed difference (P<0.05) in deviation of sex ratio when comparing the control group (45.2% females) with the other spermatozoa selection procedures (60.6% females) (P<0.05). The sperm selection methods are capable of selecting X-bearing spermatozoa without compromising the spermatozoa fertility (cleavage and blastocyst rates, 70% and 26%, respectively) and were considered relevant methods to be introduced in bovine in vitro produced embryo programs.