414 IMPROVEMENT OF EMBRYO QUALITY BY THE REPLACEMENT OF THE LAST TWO DOSES OF PORCINE FOLLICLE-STIMULATING HORMONE BY EQUINE CHORIONIC GONADOTROPIN IN SUPERSTIMULATED SINDI DONORS

Abstract

Results from a previous experiment (Barros C et al. 2008 Reprod. Fertil. Dev. 20, 152 abst) have shown that the replacement of porcine FSH (pFHS) by eCG on the last day of the superstimulatory treatment in Nellore (Bos indicus) cows resulted in a greater superovulatory (SOV) response as compared with treatment exclusively with pFSH. However, another study (Sartori R et al. 2009 Reprod. Fertil. Dev. 21, 245-246 abst) in Nellore heifers did not corroborate those observations. The aim of this study was to evaluate the SOV response of Sindi (Bos indicus) donors submitted to this protocol. Forty-eight SOV treatments were performed in a crossover design in 19 nulliparous and primiparous females that were randomly divided into 2 groups: FSH (n = 24), which consisted of 8 pFSH injections (Folltropin^®-V, Bioniche Animal Health; Belleville, Ontario, Canada), or FSH-eCG (n = 24), which consisted of 6 pFSH injections followed by 2 eCG injections (Folligon^®, Intervet Schering-Plough Animal Health, Brazil). Each female underwent 2 or 3 SOV treatments that consisted of an i.m. injection of 2 mg of estradiol benzoate (Gonadiol^®, Intervet) and the insertion of an intravaginal progesterone-releasing device (DIB^®, Intervet) on Day 0. On Day 4, the superstimulatory treatments (100 or 150 mg of pFSH, based on previous history of SOV responses) were initiated and given in decreasing doses twice a day over a 4-day period. In the FSH-eCG group, the last 2 doses of pFSH were replaced by 2 doses of eCG (150 or 200 IU of eCG each). At the time of the fifth and sixth injections of FSH, 0.150 mg of PGF2 (Preloban^®, Intervet) was injected i.m. The DIB^® device was removed at the time of the last FSH or eCG injection and ovulation was induced with 0.2 mg of GnRH (Fertagyl^®, Intervet) 12 h later. All females were artificially inseminated with frozen-thawed semen from the same bull 12 and 24 h after GnRH treatment. Seven days after the first AI, embryos/ova were recovered. Superstimulatory (number of follicles ≥6 mm at the time of the last FSH or eCG injection) and SOV (CL number) responses were determined by transrectal ultrasonography. Data were analyzed using generalized linear models and results were presented as least squares means ± standard error. The FSH-eCG group had higher superstimulatory (33.3 ± 3.9 v. 24.2 ± 3.0 follicles; P ≤0.06) and SOV (16.8 ± 2.9 v. 10.8 ± 2.1 CL; P ≤ 0.10) responses. Although the number of total ova/embryos recovered was not different between groups (8.2 ± 1.8 v. 5.9 ± 1.4 for FSH-eCG and FSH groups, respectively; P > 0.25), the number (6.5 ± 1.2 v. 2.4 ± 0.7; P ≤ 0.008) and percentage (75.2 ± 6.6 v. 52.8 ± 8.6%; P ≤ 0.05) of viable embryos was greater for the FSH-eCG females. Contrasting with the results in Nellore heifers, this study observed improvement in superstimulatory and SOV responses and embryo quality by replacing the last 2 doses of pFSH by eCG in Sindi donors.

Financial support from FAPESP, EMBRAPA, Intervet Schering-Plough Animal Health, Nutricell, and Sindi do ACS of Brazil.