Cryopreservation of Sahiwal bull epididymal spermatozoa

The objective of this study was to evaluate tris-citric egg yolk cryodiluter for cryopreservation of sahiwal bull epididymal spermatozoa. sahiwal bull epididymal spermatozoa were recovered from eight slaughtered bulls. semen retrieved from cauda of each testis pair was pooled and diluted in tris-citric egg yolk extender having 30 × 10 spermatozoa ml-1. after dilution semen was filled in 0.5 ml straws,cooled to 5 °c within two hours and equilibrated for four hours at 5°c the straws were held at liquid nitrogen vapours for 10 minutes and then plunged into liquid nitrogen for storage. sperm motility,plasma membrane and acrosomal integrity of each semen sample were assessed post thaw. sperm motility of sahiwal epididymal spermatozoa was 50.6±1.5,33.8±0.9 and 18.1 ±1.3 percent at 0,2 and 4 hour post thaw,respectively. percentage of intact plasma membrane was observed 70.5±1.4,52.9±1.0 and 40.0±1.6 at 0,2 and 4 hour post thaw,respectively. the percentage of spermatozoa with normal acrosomes was 79.1±0.4,75.1±0.2 and 71.5±0.2 at 0,2 and 4 hour post thaw,respectively. in conclusion,tris-citric egg yolk cryodiluter may be used for the cryopreservation of sahiwal bull epididymal spermatozoa. copyright 2010 zoological society of pakistan.