Effect of Equilibration Times on Sperm Cryopresevation of Juvenile Rainbow trout (Oncorhynchus mykiss W., 1792)

Abstract

The effects of four equilibration times (0, 5, 10 and 15 min) and three diluents (0.3 M glucose, 0.6 M sucrose and Erdahl andGraham’s) on post-thaw spermatozoa in juvenile Rainbow trout (Oncorhynchus mykiss W., 1792) were examined by sperm motility percentage and duration. The sperm was frozen in straws in liquid nitrogen vapour and stored for one weeks in liquid nitrogen (LN2). They were then thawed in a 25 º C water bath for 30 s. Among the four different equilibration times tested, 0 and 5 min yielded the highest mean post-thaw motility percentage (P<0.001). The 10 and 15 min equilibration of spermatozoa in diluents
before freezing significantly lowered the duration of post-taw sperm motility (P<0.001). No significant difference among three diluents was observed in post-thaw motility percentage and duration at each equilibration times. Our results showed that any equilibration time between 0- and 5-min in 0.3 M glucose, 0.6 M sucrose or Erdahl and Graham’s diluent was suitable equilibration time for R.trout sperm.