Técnica de colabamento manual da blastocele de embriões equinos e uso de progesterona injetável na manipulação do ciclo estral de bovinos e ovinos

Abstract

The development of low-cost strategies to facilitate the preservation of germplasm, as well as to anticipate the beginning of the reproductive activity of females, is essential to increase the efficiency of herds. Considering this statement, this dissertation had as objectives: (1) to review the methods and supports used for cryopreservation of equine embryos; (2) to determine the feasibility of a manual embryonic microsection technique to reduce the blastocoel of equine embryos in order to improve their cryotolerance to vitrification; (3) to determine the influence of the application of injectable progesterone (iP4) on Bos taurus heifers before a fixed-time artificial insemination (FTAI); and (4) determine the feasibility of using iP4 to induce and synchronize estrus in ewes duringa anestrous season. In the published review on methods and supports for cryopreservation, became clear the need to advance knowledge on how to cryopreserve large-diameter embryos and study alternatives for reducing the volume of the blastocoel. In article 2, submitted for publication, the proposed simplified techniques did not improve the cryotolerance of micromanipulated equine embryos. The hypothesis is that the damage to the embryo capsule has been excessive. In the following chapters, the feasibility of using iP4 in heifers previous to FTAI protocol was tested, not influencing on the anticipation of puberty or pregnancy rates. In ewes during anestrous season, the use of iP4 affected the rate of estrus and pregnancy. The results obtained with the micromanipulation techniques of equine embryos and application of iP4 in heifers and ewes, were not satisfactory, being evident that its use is not recommended until further studies are carried out.