Embryo recovery rate in Santa Ines ewes subjected to successive superovulatory treatments with pFSH

The effect of two successive superovulatory treatments was assessed in 15 Santa Ines ewes synchronized with 60 mg medroxyprogesterone acetate sponges for 14 days and superovulated with 200 IU of porcine FSH (pFSH) in decreasing doses at 12 h intervals during days 12–14 of progestagen treatment. Estrus was observed from 12 h after sponge removal and the ewes in estrus were hand mated with Santa Ines rams of proven fertility. All embryos were recovered by laparotomy 6–7 days after estrus. Treated ewes showed estrus from 24 to 72 h after sponge removal. The time of onset of estrus after sponge removal and the length of estrus were not affected (P>0.05) by the repetition of treatment. Ewes that failed to superovulate in the first and the second treatment (P>0.05) were 27 and 40%, respectively. The mean ovulation rate for those ewes responding to treatment was similar (P>0.05) between the first (9.9±1.1) and the second (11.3±1.9) treatment. There was no significant difference in fertility between the first (53%) and second (40%) treatment. Among those fertilized, viable embryos were detected for 78% in the first treatment and 64% in the second treatment (P>0.05). It was concluded that Santa Inês ewes respond to superovulatory regimes with pFSH and the treatment may be repeated for at least two times.