404 SUPEROVULATORY RESPONSE IN BEEF DONORS TREATED DURING THE FIRST FOLLICULAR WAVE OR FOUR DAYS AFTER PROGESTERONE AND ESTRADIOL ADMINISTRATION

Abstract

Although we have previously shown that ovarian superstimulation during the first follicular wave resulted in a successful response (Carballo Guerrero D et al. 2009 Reprod. Fertil. 21, 242), the current protocol needs to be optimized in order to be used in the field. Therefore, an experiment was designed to simplify this treatment and to compare it with the traditional superstimulation protocol using progesterone and estradiol. Simmental cows (n = 14) were subjected to 3 superstimulation treatments (2 first wave groups and 1 control group) in a crossover design (i.e. all cows received the 3 treatments and all treatments were represented on each collection day). Cows in Group 1 received a progesterone-releasing device (Cue-Mate^®, Bioniche Animal Health, Belleville, Ontario, Canada) along with 0.150 mg of D + cloprostenol (PGF; Bioprost-D^®, Biotay, Buenos Aires, Argentina) at random stages of the estrous cycle. A second PGF was injected 5 days after Cue-Mate^® insertion, followed by GnRH (0.050 mg of lecirelin; Biosin-OV^®, Biotay) 36 h later (i.e. 7 days after Cue-Mate^® insertion). Based on previous studies, ovulation was expected to occur 30 to 36 h later. Therefore, superstimulation treatments were initiated 36 h after GnRH (Day 0), with a total dose of 400 mg NIH-FSH-P1 of Folltropin^®-V (Bioniche Animal Health) in twice-daily decreasing doses over 4 days. Prostaglandin was administered with the last 2 Folltropin^®-V injections and Cue-Mate^® devices were removed with the last Folltropin^®-V injection. Cows received 12.5 mg of porcine LH (Lutropin^®-V, Bioniche Animal Health) 24 h after Cue-Mate^® removal and were AI 12 and 24 h later. Ova/embryos were collected 7 days after porcine LH and evaluated following IETS recommendations. Cows in Group 2 were treated similarly to those in the Group 1, except they did not receive the second PGF injection 5 days after Cue-Mate^® insertion (thus eliminating the need to handle animals on that day). Finally, cows in Group 3 [estradiol benzoate (EB)+P4 control group] received a Cue-Mate^® plus 2.5 mg of EB (Bioestradiol^®, Biotay) and 50 mg of progesterone (P4; Lab., Rio de Janeiro, Argentina) at random stages of their estrous cycle. Superstimulation treatments were initiated 4 days later (Day 0) following the same protocol used in Group 1. Data were transformed to square root and analyzed by ANOVA. Mean (± SEM) numbers of ova/embryos collected, fertilized ova, and transferable embryos did not differ among groups (12.9 ± 2.0, 9.8 ± 1.7, and 6.6 ± 1.2; 11.5 ± 1.7, 9.3 ± 1.5, and 7.7 ± 1.6; and 14.5 ± 2.8, 9.4 ± 2.3, and 6.8 ± 1.7 for Groups 1, 2, and 3, respectively). In conclusion, data demonstrated that superstimulation during the first follicular wave can be successfully used in groups of randomly cycling donors without the need for estrus detection or estradiol to synchronize follicular wave emergence. The protocol is easy to follow and embryo production is comparable to that of the estradiol and progesterone protocol.