ABSTRACT
Three experiments were performed to adapt a synchronization protocol of estrus synchronization and ovulation to be used in fixed time artificial insemination programs (FTAI) in tropically adapted Bos taurus cows. In Exp. 1 (crossover) multiparous Curraleiro Pé-Duro cows (n= 12) received an intravaginal device containing 1g of P4 for 8 days and 2mg of EB at the time of device insertion (Day 0). On the P4 device removal (Day 8) females received 150g of D-cloprostenol Sodic and 300IU of equine chorionic gonadotropin (eCG). Then, they were randomly divided to receive 1mg of EB on Day 8 (EB8) or on Day 9 (EB9). EB9 delayed ovulation approximately 15 hours (P<0.05). In Exp. 2, protocols using progesterone for eight (P4D8) or nine days (P4D9) were evaluated, resulting in similar parameters of folicular and luteal development (P>0.05). In Exp. 3, EB8 and P4D9 protocols were used to evaluate the pregnancy rate, reaching 23% (10/43) and 20% (9/45), respectively (P>0.05). Although P4D9 protocol has shown improvement in proportion of animals that responded to the protocol when compared to EB8 protocol, it was not able to improve pregnancy rate.
Keywords:
curraleiro pé-duro; fertility; ovulation; reproduction; synchronization
