Efecto de dilutores en base a tris, tes y leche descremada en la criopreservaciÓn de espermatozoides obtenidos del epidÍdimo de alpaca

The objective of this study was to evaluate the effect of three semen extenders (skim milk, Tris, and Tes) on cryopreservation of epididymal alpaca sperm. Previously, the effect of timespan since slaughtering or castration to the recovery of epididymal sperm was evaluated. Twenty-four alpaca testicles were used to obtain sperm from the epididymis in a buffered saline solution (PBS). The recovery of spermatozoa was performed at 0, 35, 48, and 72 hours (6 testes per group) after slaughtering or castration. Sperm motility, concentration, and sperm membrane functional integrity were analyzed. Sperm recovered after 35 hours was not usable for cryopreservation. Sperm samples recovered at 0 hours were subjected to the process of freezing. Samples were diluted with skim milk, Tris, and Tes, cooled from 35 to 5 °C in 90 minutes, packed into 0.25 ml straws and frozen in liquid nitrogen. After thawing, straws were evaluated by motility, sperm membrane functional integrity and vitality/acrosome integrity. Motility was 17.0, 14.0, and 8.6% on skim milk, Tris and Tes groups respectively, where the skim milk group was significantly better than the Tes (p<0.05). Percentages of sperm membrane functional integrity and vitality/acrosomal integrity were similar among the three extenders. It was concluded that all three extenders provided similar effects for the cryopreservation of epididymal alpaca spermatozoa.