COMPARISON BETWEEN ESTRADIOL AND GNRH-CIDR BASED PROGRAMS ON SUPER OVULATION IN HOLSTEIN COWS/HEIFERS

Objectives: The aim of the current study is to compare the response of GnRH-CIDR and estradiol-CIDR based programs on super ovulation outcomes in Holstein cows. Methods: 12 Holstein cows/heifers were divided into two groups. Groups (A/N=7) synchronized with GnRH and group (B/N=5) synchronized with Estradiol. Both treated groups received progesterone releasing intravaginal device (CIDR) at day (0) and removed at day (7). Group (A) received GnRH (Receptal? /10 ?g) at day (2 and 8) and Group (B) received estradiol benzoate at day (0). Both groups were super stimulated with Follicle-stimulating hormone (Follitropin-V) twice daily from day (4) to day (7). Cloprostenol (Estrumate?/500?g) was administrated at a day (7PM& 8 PM) in group (A) and at day (6AM&PM) for group(B). Cows/heifers were subjected to artificial insemination at day (9AM&PMand 8PM&9AM) for group (A) and (B) respectively. The embryo flushing was done at day (16) for group (A) and at day (15) for group (B). Results: The total number of recovered embryos was better in group (A/55) than group (B/45); although the recovered embryos per flush was 7.86 for group (A) which was lower than that of group (B/9). Even though, the embryo quality was better in group (A) as follow: 47.2% embryo grade I , 21.8% embryo grade II, 12.7% embryo grade III, 18.1% embryo grade IV, while they were 33.3%, 28.8%,11.1% and 26.6% respectively in group (B). The pregnancy rate in the recipient heifers were 30.90% and 24.44% for group (A) and (B) treated donors respectively. Conclusion: GnRH-CIDR based program was better than estradiol-CIDRbased programon super ovulation in Holstein cows especially in terms of embryo quality, and pregnancy rate.