Eficiência reprodutiva de novilhas búfalas submetidas à protocolos de indução de ciclicidade.

Abstract

This study aimed to evaluate the reproductive efficiency of prepubertal buffalo heifers at the end of the breeding season, after receiving a puberty induction protocol, followed by an FTAI protocol, both based on P4 and E2. At the beginning of the puberty induction protocol, the heifers received a fourth-use progesterone-releasing intravaginal implant (P4). This implant remained in the animals for 10 days. After 10 days from the beginning of the induction protocol, the implant was removed and in animals that were acyclic, 0.5 mg of estradiol cypionate was administered. The animals were divided into 3 experimental groups regarding the time to receive the puberty induction protocol: Induction group45 – received the puberty induction protocol on Day -55, with the end of the induction protocol on Day -45 and the beginning of the protocol of FTAI on Day 0; the Induction12 group - received the puberty induction protocol on Day -22, with the end of the induction protocol on Day -12 and the beginning of the FTAI protocol on Day 0; Control group - did not receive a puberty induction protocol, only the FTAI protocol starting on Day 0. The animals in all groups were kept in the same management batch and started the FTAI protocol at the same time (Day 0). After 15 days of fixed-time artificial insemination, the animals were kept with a bull in the proportion of 1/25. Thirty days after FTAI, the pregnancy diagnosis was performed by ultrasound, the pregnancy rate of the Induction45 group was 42.2%, Induction12 group was 44.2% and the Control group had a pregnancy rate of 21.8 %. The animals that had not yet reached puberty, after the FTAI protocol, managed to become pregnant in the transfer with a bull in the breeding season, and also the induced heifers showed a tendency to become pregnant earlier than the control group. It was concluded that puberty induction protocols in prepubertal buffalo heifers increase pregnancy after FTAI, and that the 12-day interval between the end of induction and the beginning of the FTAI protocol can be recommended, as it presents similar P /IA than the 45-day interval, in addition to being shorter. The FTAI protocol based on P4/E2 is able to equalize the pregnancy rates of the transfer with the bull at the end of the breeding season and anticipate the moment of conception, in addition, the FTAI protocol increased the efficiency of the control group.