Fresh, equilibrated and post-thaw sperm quality of Brycon orbignyanus (Valenciennes, 1850) and Prochilodus lineatus (Valenciennes, 1837) treated with either salmon GnRHa and domperidone or pituitary extract

The effects of reduced doses of OvaprimTM (GnRHa + domperidone) on sperm release of Brycon orbignyanus and Prochilodus lineatus were evaluated. Furthermore, sperm quality was compared among fresh, equilibrated and postthaw samples. Males received a single and reduced dose of OvaprimTM (0.125 or 0.25 ml/kg); control males received pituitary extract (cPE; 3 mg/kg). Fresh sperm was evaluated for volume, concentration, seminal plasma osmolality and seminal plasma pH. Then sperm was diluted in a freezing medium, equilibrated for 15-20 min and frozen in nitrogen vapor vessel (dry-shipper). Sperm motility was analyzed during 60 s post-activation in fresh, equilibrated and post-thaw samples. Sperm quality of males treated with OvaprimTM (both doses) were not different from that of cPE-treated males, thus these data were pooled. In B. orbignyanus, motility was higher in fresh (99%) than in equilibrated sperm (81%); post-thaw motility dropped to 42%. In P. lineatus, motility was similar in fresh (99%) and equilibrated sperm (92%); post-thaw motility was 73%. Motility decreased as a function of time post-activation, and this decrease was significant after 60 s in fresh and equilibrated sperm, and as soon as 30 s in post-thaw sperm, in both species. OvaprimTM at 1⁄4 of the recommended dose can successfully replace cPE.