Comparison of different methods of goat sperm selection and capacitation for optimization of assisted reproductive technologies

• Mini-Percoll gradient was successfully used for goat frozen-thawed sperm selection.
• Mini-Percoll gradient was better than swim-up and similar to washing method.
• Sodium nitroprusside (SNP) did not promote any damage to sperm.
• 100 μM SNP resulted in better motility and vigor than heparin for capacitation.

This study evaluated different methods of frozen–thawed sperm selection and capacitation in goats for further use in reproductive biotechnologies. In Experiment 1, semen was processed by the following techniques: mini-Percoll, swim-up, or washing by centrifugation. In Experiment 2, mini-Percoll selected-sperm was subjected to capacitation induction by incubation with: 50 μg/mL heparin, 10 μM, 50 μM, or 100 μM of sodium nitroprusside (SNP). Motility, vigor, acrosome, and plasma membrane (PM) integrity were evaluated after thawing and after each treatment of sperm selection or capacitation. In Experiment 1, washing by centrifugation presented greater (43%; P < 0.05) spermatozoa recovery rate than the other treatments. The swim-up technique showed the lowest (P < 0.05) progressive motility (41%). Spermatozoa presenting both intact PM (P = 0.0002) and acrosome (P = 0.0004) showed an interaction effect between the buck and swim-up technique. In Experiment 2, the addition of 100 μM SNP resulted in greater (P < 0.05) motility and vigor (38%; 4.7), respectively, than did heparin (28%; 4.3). An enhancement (P < 0.05) in vigor was obtained after all treatments in comparison with the evaluation after thawing (3.3). In conclusion, mini-Percoll was better than swim-up for preparing frozen–thawed goat sperm, whereas washing by centrifugation technique presented similar rates to mini-Percoll and could also be used. The use of 100 μM SNP resulted in better motility and vigor than heparin treatment.