EFECTO DE LA COPULACIÓN DURANTE EL CELO POSTOVULATORIO EN LA MORTALIDAD EMBRIONARIA EN ALPACAS

Abstract

The objetive of this research work was to study the effect of the frequency of copulation during the post-ovulatory estrous on the embryonic mortality in alpacas. Forty four female alpacas were selected having a post-partum sexual rest >20 days and bearing in the ovaries a pre-ovulatory follicle >7 mm of diameter. Animals were mated (time of coitus: >15 minutes) using a male with proven fertility and received 6 �g of busereline i.m. after copula to ensure ovulation. Three experimental groups were then ramdomly organized: the first group (S 1 , n = 14) did not receive additional matings, the second gropup (S 2 , n = 15) received an additional mating on day three post-ovulation, and the third group (S 3 , n = 15) received additional matings on days three and four postovulation. Ovulation was confirmed through ultrasound images by disappearance of the pre-ovulatory follicle 42 hours post-mating and the presence of a corpus luteum on day 5 post-ovulation. In addition, the size of the corpus luteum, morfological changes of the uterine horns and presence of an embryo were recorded on days 13-14 and 19 postmating. These observations were complemented with the observation of sexual receptivity using a male on days 6, 13-14, 19 and 26 post-mating. Ovulation rate was 91%. There was a higher tendency on embryo survival at day 19 post-mating in those alpacas that received an additional mating on days 3 (S 2 = 80%) and 3 and 4 (S 3 = 85%) post-ovulation than in those animals without additional mating (S 1 = 75%). An additional study in four inducedovulated alpacas was done to detect fertilized ova at days 2, 3 and 4 post-ovulation. Recovery of the fertilized ova from oviduct was possible only until day 3 post-ovulation.