SELECTION OF FROZEN BULL SPERMATOZOA FOR IN-VITRO FERTILIZATION

The swim-lip and Percoll gradient techniques were evaluated for the se lection of frozen bovine spermatozoa to be used on an in vitro fertili zation system. The parameters assayed were: concentration, morphology, motility and rate of in vitro fertilization and rare of development. The spermatozoa were from a single bull and the oocytes were aspirated from ovaries obtained at the slaughter house and matured in vitro. Sp erm motility increased significantly (p < 0.05) from 70% - 75% to 90% - 95%. However after sperm selection there was no significant differen ce between both methods (p > 0.05). Sperm concentration after swim-up was 3.33 x 10(6) sp/ml and with Percoll 16.5 x 10(6) sp/ml (p < 0.01). Samples obtained by both methods showed a decrease in abnormal sperma tozoa as compared to controls (17.3% in swim-up; 24.8% in Percoll and 47% in control) (p < 0.01). There was a significant difference between both methods only in regards to anomalies of the neck region (3.5% in swim-up and 9.6% in Percoll (p > 0.05)). A total of 915 oocytes were used for the study. No significant differences were found between both methods when the rate of fertilization was evaluated by acetorcein an d supravital Hoechst methods (27.3 and 54.3% for swim-up and 38.5 and 55.6% for Hoechst) respectively. In conclusion, both methods of sperm selection seem to be adequate for in vitro fertilization techniques.