Objectives: The aim of the current study is to compare the response to GnRH-CIDR and Estradiol-CIDR based programs on super ovulation rate in Holstein cows/heifers. Methods: Twelve animals divided into two groups. Group (A, N= 7), while group (B, N=5). Both groups received progesterone injection (intra-vaginal progestrone-releasing device- CIDR) on day (0) and removed on day (7). On day 2, group (A) received GnRH (Receptal® 10µg), after that the animals stimulated using decreasing doses of follicle-stimulating hormone (Follitropin-V) twice daily (7am-7pm) starting from the day (4) to the day (7). On day (7) at (7pm) the first group was injected with Estrumate®/500μg coinciding with the time of CIDR removal. On day (8) the first group received another dose of Estrumate 500μg, together with Receptal®10μg at 7:00 pm. Artificial insemination was set to be on day (9) at 7:00 am & pm. The second group, coinciding with CIDR application on day (0), injected with Estradiol benzoate 2.5mg. After that, ovulation was stimulated by using decreasing doses of Follitropin-V twice daily (7am-7pm) from day 4 to day 7. On day (6) exactly at (7pm) animals received Estrumate 500μg. On day (8) at (7am) animals received a dose of Cystorelin 100mg, and then artificially inseminated at (7pm) on the same day. Again, animals received fixed A.I at (7am) on day (9). Embryos were collected on day (16) for group (A) and on day (15) for group (B). Results: The total number of recovered embryos was better for group A (55) than group B (45). Although the number of recovered embryos/flush/animals were (7.86) group A, which was lower than group B (9). Despite this, the embryos quality was better in group A. Where, it recorded (47.27%) grade (I), (21.81%) grade (II), (12.72%) grade (III), and (18.18%) grade (IV), while it was (33.33%), (28.88%), (11.11%), and (26.66%) for group B, respectively. The pregnancy rate for the recipient cow was (30.90%) and (24.44%) for group (A) and (B), respectively. Conclusion: for Holstein cows the program based on GnRH-CIDR was better than the program based on estradiol-CIDR concerning super ovulation rate, embryo quality, and pregnancy rate. |
