Short-term sperm storage protocol for an endangered Mexican fish acúmara (Algansea lacustris)

Cold sperm storage is a simple and inexpensive technique to assist reproduction programs for endangered species. This study aimed to describe sperm quality indicators and develop a cold sperm storage protocol for Algansea lacustris. A total of 8 storage conditions were evaluated: Control 1 (undiluted sperm), Control 2 (sperm diluted in extender BTS™), and 6 different combinations of the extender (Control 2) + : (1) 2.5 % Me2SO, (2) 5 % Me2SO, (3) 7.5 % Me2SO, (4) 10 % Me2SO, (5) 12.5 % Me2SO, and (6) 15 % Me2SO for 0, 24, 48, 72, and 96 h. The motility and duration of moving sperm were assessed daily for each treatment. Samples diluted in the highest concentrations of Me2SO (12.5 % and 15 %) showed a lower motility rate (60–79 %) immediately after dilution (0 h). Undiluted sperm samples (Control 1) showed a higher motility rate (62 %) after 72 h and higher duration of motility (33.8 s) after 48 h. The optimal storage condition for obtaining about 60 % motility is storing undiluted sperm for up to 72 h. However, the combination of extender BTS™ at 5 % and cryoprotectant Me2SO at 10 % present future potential for enhancing the spermatic cryopreservation protocol in Algansea lacustris.