Sêmen refrigerado e seu potencial de uso na inseminação artificial de búfalas ( Bubalus Bubalis )

Abstract

Bubalinoculture exploitation has been growing steadily in recent years. In this context, the use of reproductive biotechniques such as fixed-time artificial insemination (FTAI), follicular aspiration (OPU) and in vitro embryo production (IVP) have been shown to be feasible in buffaloes, although still with reduced efficiency and with little commercial application compared to other animal species. This is due to particular characteristics of the species, such as difficulty in identifying the estrus and the complication in conditioning bulls for the collection of semen with the artificial vagina, mainly adult animals. Added to this, even the animals after the conditioning and collection of semen, does not maintain a constancy in the production of ejaculates with quality, even interrupting the production of semen without an apparent reason. In part, these problems have been solved with the elaboration of protocols that allow the use of AI without the need of detection of estrus, that is, in fixed time (FTAI). Already the knowledge of the follicular dynamics in this species allowed the development of protocols to control the follicular and luteal phases of the estrous cycle and, finally, ovulation. The combination of these ovulation synchronization treatments allows the use of artificial insemination throughout the year, allowing the genetic gain and distribution of conception and delivery according to market demand. However, artificial insemination in buffaloes, which is based on the use of frozen semen, presents some bottlenecks such as: the lack of semen in the national market; bulls with superior genetics, but that do not resist the freezing process; injuries caused to the spermatozoa during the freezing process, which can cause up to 60% decrease in the viability of the sperm population in buffaloes and the existence of basic management deficiencies in the properties. In the light of the above, this study aims to test the efficacy of refrigerated and frozen semen on FTAI in favorable and unfavorable reproductive periods, as well as in vitro fertilization to improve fertility rates, to study the expression of sexual behavior of buffalo bulls and, the application of rational management techniques during the period of collection of semen with the artificial vagina, aiming to facilitate the conditioning and collection of semen, as well as to develop new extensors for buffaloes semen. The results obtained with the artificial inseminations during the favorable and unfavorable reproductive period showed superior pregnancy rate for the refrigerated semen. This result was also obtained with IVP. Regarding the behavior of the bulls, it was verified that these animals can be conditioned for the collection of semen with artificial vagina in the field. After several tests it was verified that the TRIS diluent with 10% LDL plus 0.5% soy lecithin and with the addition of 10 mM of the antioxidant acetylcysteine showed the best longevity and fertility results invitro.