Effect of Diluents and Storage Time on the Cryopreservation of Collared Peccary (Pecari tajacu) Semen after Cooling Storage in a Transport Container at 5 C

We verified the possibility of cooling peccary semen for 4, 24, and 48 h before cryopreservation, using different dilution media (TRIS + egg yolk (20%) and PRIMXcell Ultra). Ten ejaculates were divided equally into six aliquots and then diluted. Two aliquots were stored in a biological incubator (4 h), and the remaining aliquots were stored in a commercial container, the Botutainer (R) (24 and 48 h), both at 5 degrees C. The samples were cryopreserved and then evaluated for kinetic parameters, functionality, integrity, mitochondrial activity, morphology, and sperm binding capacity. After thawing, samples diluted in TRIS showed total motility of 43.4 +/- 6.8%, 48.4 +/- 6.2%, and 38.6 +/- 5.0% after cooling for 4, 24, and 48 h before cryopreservation, respectively. Such results are significantly greater than those achieved with the use of PRIMXcell diluent for 4 (8.3 +/- 2.8%), 24 (4.7 +/- 1.4%), and 48 h (4.8 +/- 2.9%) storage (p < 0.05). Furthermore, TRIS provided better preservation of sperm membrane integrity when samples were cooled for 24 h (44.5 +/- 4.7%) before cryopreservation compared to those samples diluted in PRIMXcell Ultra stored for 24 (25.7 +/- 4.0%) and 48 h (25.2 +/- 4.0%) before freezing (p < 0.05). In summary, we suggest TRIS diluent + egg yolk (20%) as an effective option to allow semen to cool for 24 or 48 h in a transport container before cryopreservation.