Creación de un banco de embriones a partir de un protocolo de superovulación para el mejoramiento genético del hato ovino de la granja experimental de Nero

Abstract

The objective of this study was to evaluate a superovulation protocol with the purpose of creating an embryo bank for the genetic improvement of the existing sheep flock at the “Nero” experimental farm. To meet this objective, 10 female sheep of the corriedale and katahdin breed and 2 male breeders of the dorper and katahdin breeds were used; the animals had a body condition of 3 ± 0,5; an average age of 3,5 ± 1 years; and an average weight of 60 ± 10 kg. The superovulation protocol employed was: day 0 intravaginal sponge application with 200 mg of medroxyprogesterone acetate (MAP), day 4 sponge replacement; days 8 to 11 administration of FSH in decreasing doses, equivalent to a total of 200 mg; day 10 the sponge was removed and 25 mg prostaglandin F2 alpha was applied; day 12 mating with 3 mating/day every 6 h. At 6 days after 6 days the last mating, retrograde lavage by exploratory laparotomy of the uterine horns was performed. As a result, 50 % (5/10) of the ewes responded to the superovulation protocol recovering the following structures: morulae= 31, blastocysts= 7, unfertilized oocytes= 3. A total of 71 CL (9.91 ± 2.04 mm) and 9 follicles (3.88 ± 0.33 mm) were recorded. There was also a positive correlation (r=0.413, P <=0.0001) between corpus luteum size and embryo quality. In conclusion, the response of the superovulation protocol allowed obtaining a total of 37 freezable and transferable embryos.