Synchronization of estrus and ovulation in heifers girolandas: comparison between the protocols hormonal 'cidr-b' and 'ovsynch

Two oestrus and ovulation synchronization protocols (CIDR-B and OVSYNCH) were tested on 90 acyclical Girolanda heifers. The animals were distributed in three groups. Group I (n=30) was submitted to the OVSYNCH protocol, consisting of: intramuscular (IM) application of 1.0 ml gonadotropin-releasing hormone (GnRH), 2.0 ml rostaglandin F2a (PGF2a) after 7 days, 1.0ml GnRH 48h later, then timed artificial insemination (TAI) 16h after the second application of GnRH. Group II (n=30) was submitted to the CIDR-B protocol, consisting of: introduction of intravaginal CIDR-B implant and application of 2.0 ml estradiol benzoate (EB) IM, implant removal after 8 days, application of 500 UI pregnant mare serum gonadotropin (PMSG) and 2.0 ml PGF2a, a second IM application of BE 24h subsequently, then TAI 30h later (i.e. 54h following implant removal). Group III (n=30; control group) received no hormonal treatment. Gestation was verified ltrasonographically 35 days after the first, second and third AI. The cost-benefit ratio of each protocol was also determined: The CIDR-B protocol was most efficient in the first AI in which it was comparable to the control group in providing a near-natural oestrus quality (conception and pregnancy rates of 60% and 50%, respectively; p