OOCYTE TRANSFER IN MARES

Abstract

The progress of reproduction biotechnologies in horses are slow compared to other species. This is due to the large number of anatomical peculiarities inherent to the species and also by the limited availability of research material. Products from females of high genetic pattern, through the ovary conservation became possible, determining the continuity of genetic material through techniques like Oocytes in Vitro Maturation (IVM) and Oocyte Transfer (OT). Potential candidates to oocyte donors are older females and / or affected by ovarian, uterine, cervical disorders, and mares that have not had good results in Natural Mating (NM), Artificial Insemination (AI) and / or TE (Embryo Transfer) without apparent or acquired causes during their reproductive life. To obtain oocytes for transfering in good conditions, some hormonal protocols are used in order to accelerate follicular and oocyte maturations. Nowadays, collection of oocytes is made by aspiration and washing of the follicles guided by transvaginal ultrasound (TVA), however, punches through the flank or laparotomy with ovarian follicles exposure and aspiration have been reported with success. The ovarian oocytes from slaughterhouse are the most abundant gametes sources, excellent experimental models and training materials for valuable mares that may die. TO's success depends on several factors: one of the most important is related to the oocyte origin and in vitro maturation difficulty, resulting in embryonic development low rates. Oocytes from pre-ovulatory follicles, matured in vivo are higher than the ones matured in vitro. The quality and type of semen conservation also interfere in the results, as well as the donor and recipient age, determining success ful factor. Thus, it is a great prospects biotechnology with use still restricted because there are littler knowledge. The aim of this review is to address the relevant points for understanding and oocytes transfer technique development in mares.