USE OF PROGESTERONE IN SUPEROVULATION PROTOCOLS FOR EMBRYO PRODUCTION IN FRIESIAN COWS

Abstract

The current study was designed to determine the effect of different superovulation regimens on ovarian follicular dynamics, superovulatory response and embryo production in Friesian cows. A total of 24 Friesian cows (450-550 Kg LBW, 3.5-5.5 years old and 1-3 parities) were used as donor cows. Cows were divided into 3 groups (8 animals in each group). Cows in the 1st group (Control) before treatment, donor cows were injected i.m. with 2 ml PGF2α to bring them on heat to start oestrous cycles. All cows were injected i.m. with a single dose of 3000 IU PMSG on day 10 of the estrous cycle then injected with 3 ml PGF2α 48 h later. However, in the 2nd group, at random stages of the oestrus cycle cows received Syncro-Mate-B (SMB) implant together with one i.m. injection of 5 mg from estradiol benzoate and 100 mg progesterone, then cows were injected with PMSG (3000 IU) and PGF2α (3 ml) on Day 7 of treatment and implant was removed 2 d later. In the 3rd group, donor cows received Controlled Internal Drug Release (CIDR) together with one i.m. injection of 4 mg estradiol benzoate at random stages of the oestrus cycle, then cows were injected with a single i.m. of PMSG (3000 IU) and PGF2α (3 ml) at the time of CIDR removal on day 7. Cows in all groups artificially inseminated when they exhibited estrus, and flushing was conducted 7 days after AI. Ovulatory responsewas determined in terms of number of CLs as well as number and diameter of the follicles byultrasonography device.Results showed that estrus rate was 100% in all groups. Estrus incidence after PGF injection was later (P<0.05) in G2 and G3 (3.25 and 5.75 d) than in G1 (2.25 d), being (P<0.05) the latest in G3 (5.75 d), moderate in G2 (5.25 d) and the earliest in G1 (2.25 d) after the end of treatment. Percentage of cows produced embryos was higher (P<0.05) in G3 (62.5%) than in G1 and G2 (37.5%). On day of flushing, average number of CLs/cow was greater (P<0.05) in G3 (7.50) than in G1 and G2 (3.50 and 4.62), respectively. Number of un-ovulated follicles showed an opposite trend (P≥0.05). Ovulation rate was higher (P<0.05) in G3 (70.28%) than in G1 and G2 (40.00 and 56.89%), respectively. Embryo recovery rate (63.3%) and yield of total embryos (4.75/cow) at early morula, compact morula stages (1.6 and 2.5/cow) were higher (P<0.05) in G3 than in G2 (28.4%, 1.28, 0.5 and 0.4/cow) and G1 (43.2%, 1.78, 0.5 and 0.5/cow), respectively. The differences in number of embryos at early blastocyst and blastocyst stages were not significant. Number of embryos at both morula and blastocyst stages was higher (P<0.05) in G3 (4.75/cow) than in G2 and G1(1.28 and 1.65/cow), respectively.Cows in G3 produced the highest (P<0.05) number of transferable embryos (1.0 excellent and 2.25 good embryos/cow) as compared to other groups. In conclusion, using CIDR device as progesterone source in superovulation protocol gives high ovulation rate and acceptable number of transferable embryos of excellent and good grades, which may consider as a useful tool for embryo transfer.