Spermatozoa evaluation and cryopreservation in pellets fron of "bagre" Rhamdia hilarii (Valenciennes, 1840) sêmen

Abstract

The spermatic characteristics and the criopreservation of 10 and 6 "bagres", Rhamdia hilarii, sperm respectively were studied with the purpose to maintain a frozen semen bank for artificial fertilization of freshwater fishes of economical value. This paper was carried out at Laboratório de Biologia Aquática do Instituto de Pesca (São Paulo-Brazil). The average values of spermatic characteristics were: semen volume, 1.15 ml; spermatozoa concentration, 55.80 x 10⁶/mm³; spermatozoa motility, 72.00%; and percentage of live spermatozoa by differential staining method, 76.09%. The semen of each male, mixed with extender at ratio of 1:3, was frozen in pellets form on dry ice (-79°C) and storage in liquid nitrogen (-196°C). Samples thawed and examined under phase-contrast microscopy presented an average of 31.94% live spermatozoa. Spermatozoa showed 30% motility 36 months after freezing.