Cryopreservation of semen from functional sex-reversed genotypic females of the rainbow trout, Oncorhynchus mykiss

Abstract

Cryopreservation of semen from sex-reversed females of rainbow trout aims at rationalizing the production of stocks composed by 100% females. Semen from normal males (M) and two types of genotypic females (R and G), sex-reversed by the oral administration of 17α-methyltestosterone, were used. R was obtained by the fertilization of normal eggs with semen of sex-reversed females while G via gynogenetic reproduction. Semen was diluted in an extender solution (glucose 5,4 g, egg yolk 10 ml, dimetil sulfoxide 10 ml, water 80 ml) at 1:3 ratio (semen/extender), stored in straws of 0.5 ml and freezed in a dry container Cryopac CP-65, at -180°C. Thawing was performed with water at 70°C for 3 seconds. There were no significant fertilization rate differences (P>0.05) among thawed semen groups (M = 73.1±11.5%; R = 67.2±23.6%; G = 64±5.8%), confirming that the freezing methodology used was efficient to cryopreserve semen of all three trout groups.