Resumen

ALONSO VILLA, Néstor et al. Evaluación de Cuatro Protocolos de Sincronización Para Inseminación a Tiempo Fijo en Vacas Bos indicus LactantesEvaluation of Four Synchronization Protocols for Fixed - Time Artificial Insemination in Bos indicus Lactating Cows. Rev. Cient. (Maracaibo) [online]. 2007, vol.17, n.5, pp.501-507. ISSN 0798-2259.

The objective of this study was the evaluation of four synchronization protocols for fixed-time artificial insemination (FTAI) in Bos indicus lactancting cows. Brahman cows (n=120) between 60 and 120 days postpartum were randomly assigned to one of four syncronization treatments. The Crestar treatment consisted of the aplication of ear implant of norgestomet and an injection of norgestomet and estradiol valerate, on day 9 the implant was removed and the cows received an eCG injection; the FTAI was performed 48-52 hours later. In the GPG treatment the cows received an injection of gonadorelina on day 0, an injection of D-cloprostenol on day 7, a second injection of gonadorelina on day 8 and FTAI 18-22 hours later. The GPE treatment was similar to GPG, but the second dose of gonadorelina was replaced by an estradiol benzoate (EB) injection and the FTAI was performed 30-32 hours later. The CIDR-B treatment consisted of the aplication of intravaginal device, an injection of EB and progesterone, the device was removed 7 days later, at the same time the cows received an injection of D-cloprostenol, on day 8 the cows received an injection of EB and FTAI 30-32 hours later. Pregnancy was diagnosed by transrectal ultrasonography 35 days after TAI. Crestar treatment has a higher pregnancy rate (P<0,01) than the other treatments (55.7 vs 19.4, 22.5 y 21.8% respectively). The findings of this experiment show that is possible to get acceptable pregnancy rates with FTAI in B. indicus lactating cows and progesterone releasing devices plus eCG treatments should improve reproductive performance of cows.

Palabras clave : Bos indicus; fixed-time insemination; synchronization.