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.