C\u00e2mara DR, Silva SV, Almeida FC, Nunes JF, Guerra MM<\/p>\n
Department of Veterinary Medicine, Federal University of Alagoas, Vi\u00e7osa-AL. Brazil<\/em><\/p>\n The objective was to evaluate the effects of various antioxidants and duration of pre-freezing equilibration on cryopreservation of ram semen. Semen samples from four rams were pooled, diluted with Tris-egg yolk extender without antioxidants (control), or supplemented with reduced glutathione (GSH: 0.5, 1.0, and 2.0 mM), superoxide dismutase (SOD: 5, 10, and 20 U\/mL), or catalase (CAT: 5, 10, and 20 U\/mL), and cryopreserved, immediately after thermal equilibrium was reached at 5 \u00b0C (0 h), or 12 or 24 h after equilibration. Total antioxidant capacity was determined in the in natura extenders and after addition of semen samples for various durations of processing (fresh\/dilute, throughout refrigeration, and post-thaw). Plasma membrane (PI-CFDA), acrosome integrity (FITC-PNA), and mitochondrial membrane potential (JC-1) were determined in fresh\/diluted, refrigerated, and post-thaw samples. Post-thaw sperm motility was assessed with a computerized analysis system (CASA). There were no significant differences in acrosome damage or mitochondrial membrane potential after refrigeration and freeze-thaw, regardless of antioxidant addition. Sperm plasma membrane integrity was worse (P < 0.05) with cryopreservation immediately after equilibration (average 20.1 \u00b1 8.3; mean \u00b1 SD) than after 12 h of equilibration (average 42.5 \u00b1 10.9); however, the addition of SOD and CAT (10 and 20 U\/mL) resulted in no significant difference between post-equilibration intervals of 0 and 12 h. Total antioxidant activity was not different (P > 0.05) among treatments after sperm addition or throughout the refrigeration and post-thaw. In conclusion, adding GSH, SOD or CAT did not increase the total antioxidant capacity of semen, nor did it enhance the quality of the post-thaw sperm. However, maintenance of ram semen at 5 \u00b0C for 12 h prior to cryopreservation reduced membrane damage of frozen-thawed sperm.<\/p>\n doi: 10.1016\/j.theriogenology.2011.02.013<\/p>\n","protected":false},"excerpt":{"rendered":"