TIME EFFECT OF OOCYTE COLLECTION FROM OVIDUCT ON NUMBER AND QUALITY OF OOCYTE AND ITS EFFECT ON IN VITRO FERTILIZATION IN RABBIT

Quality and quantity of ovum are major determinants in invitro fertilization. The aim of the present study was to determine effect of the time of oocyte collection and also distance of HCG injection to oviduct flushing on the quantity, quality and fertilizing ability of rabbit oocyte. Accordingly, sixty two adult female rabbit selected and randomly allocated to seven groups. The rabbits were superovulated with PMSG (50 IU/head) followed by HCG (45 IU/head). Semen specimens were collected from two adult fertile male bucks using artificial vagina. Results showed, superovulation of 62 does yielded 412 oocytes (average 6. 6 oocyte/rabbit) and mean 7. 8±1. 7, 5. 3±2. 8, 5. 2±2. 7, 7. 6±2. 8, 4. 3±2, 7. 3±4 and 18. 3±7. 7 oocyte/animal for seven groups respectively. So, when flushing done after 23-30 hours of HCG injection and between hours of 19-24 of day, maximum oocyte were collected and in contrast the oocytes were minimum when flushing performed between hours of 9-14 of day at the same period, mean 18. 3 in contrast 4. 3 oocyte/rabbit respectively, this difference was significant (p<0. 01). In 7 groups value of grade A oocyte were 12. 9, 8. 1, 49. 3, 26. 2, 60. 0, 18. 2 and 54. 8 percent respectively, so the difference of the first, second and sixth groups with the third, fifth and seventh groups and also forth with seventh group were high significant (p<0. 001). From 223 oocytes were used for 27 times IVF experiments, %31 (n=69) of them were fertilized, so this value for 7 groups were 38. 5, 15. 6, 37. 6, 11. 0, 32. 0, 42. 0 and 100. 0 percent, respectively, and maximum significant difference was between seventh group with second and forth groups (p<0. 001). Results of this study proposed that the best time for oocyte collection is hours between 19-24 of day, together with 23-30 hours after HCG injection, which produce maximum number, and fertilizable oocyte in Dutch laboratory rabbit.