CENTRIFUGATION OF OVINE SPERM IN CONTINUOUS DENSITY GRADIENT: EFFECT ON PREGNANCY RATE AND SEX RATIO

The objective of this study was to evaluate the efficiency of continuous density gradients of Percoll and OptiPrep for separation of X-bearing sperm, and assess the influence on sperm viability, pregnancy rate and sex ratio. With this purpose 100 million spermatozoa were deposited into each tube containing density gradient, which were previously prepared in polystyrene tubes, 24 hours before centrifugation and stored at 4 °C. The tubes were centrifuged at 500xg for 15 minutes at 22 °C, and then the supernatants aspirated and sperm recovered from the bottom of the tubes. A sample was evaluated before and after centrifugation to verify motility and sperm vigor. The sperm were used for fixed time artificial insemination. The results indicated that centrifugation did not affect sperm viability and pregnancy rate, however there was no deviation of sex ratio for females. More studies are needed of adapting the centrifugation technique to sheep and thus obtain the deviation of sex ration as in bovine.