Efeito dos diferentes momentos de inseminação artificial laparoscópica em programas de inseminação artificial em tempo fixo em ovinos

Abstract

The use of artificial insemination (AI) accelerates the genetic improvement, prevents transmission of venereal diseases and facilitates testing of progeny besides enabling subfertile males to produce descendents. Fixed Time Artificial Insemination (FTAI) has been used successfully in which females have their estrus induced by hormonal treatment, which allows a prediction of the manifestation of estrus and ovulation and therefore the ideal time of insemination. In order, from the knowledge of time of ovulation, pre-determine the most appropriate period for the time of deposition of semen, cooled and frozen in the female reproductive tract in FTAI programs, twenty ewes had their estrus synchronized using intravaginal progesterone (Progespon ®, Coopers) for 12 days and 400 IU of equine chorionic gonadotropin [eCG (Novormon ®, Coopers)], to determine the moments leading up to ovulation. Other two hundred ewes, submitted to same protocol for synchronization of estrus, were divided into 4 groups for Artificial Insemination, with cooled semen used in groups 1 and 2 and frozen semen in groups 3 and 4. The sheep from G1 and G3 were inseminated 58 ± 1h after removal of progesterone intravaginal device (pre-ovulatory), and the sheeps from G2 and G4 were inseminated 64 ± 3h after withdrawal of progesterone intravaginal device (post-ovulatory). The results were obtained through the confirmation of pregnancy and data were subjected to statistical analysis with odds ratio and level of significance (p) less than 0.05. It having seen observed good results when used cooled and frozen semen, respectively, in the periods preceding (68% pregnancy rate) and exceeded (64% pregnancy) the 60h, respectively, after withdrawal of exogenous source of progestagen.