Criopreservação de sêmen de pacu (Piaracthus mesopotamichus) e curimba (Prochilodus lineatus): predição do potencial de congelabilidade e uso da cafeína na solução ativadora

Abstract

The first experiment aimed at determining which sperm characteristics are capable of predicting with better precision the freezing potential of curimba (Prochilodus lineatus) semen. Aliquots of 200 µL of semen, taken from eleven breeders, were diluted in a cryoprotectant solution (DMSO 10% and BTS 5%), placed in 0.5 mL sterile straws and cryopreserved in liquid nitrogen for ten days. Cryopreservation affected (P<0.05) all quality variables. Only spermatic motility and motility duration, measured in thawed semen, presented high correlation (-0.6377 and -0.7306, respectively) with the canonic variable represented by the spermatic characteristics of fresh semen. It may be concluded that motility and motility duration may be used to predict freezing potential. The second experiment aimed at evaluating the effect of different caffeine concentrations added to the activating solution in the parameters of sperm motility in pacu (Piaractus mesopotamicus) and curimba (Prochilodus lineatus) in natura and thawed semen. The activating solutions were prepared based on NaHCO3 added of caffeine in the concentrations of 0.0, 2.5, 5.0, 10.0 and 20.0 mM. For the collection of the semen, a total of 8 pacu and 20 curimba breeders were used. For the cryopreservation, the same protocol of the first experiment was used. A linear increase occurred in sperm motility for pacu and curimba in natura semen and for curimba thawed semen (P<0.05), due to the increase in caffeine concentration. A quadratic response was observed in motility duration for pacu thawed semen and for curimba in natura semen. Therefore, these results indicate that the addition of caffeine in the activation solution may improve sperm motility parameters, however, it is dependent of the species and the used concentration.