Evaluation of different diluents for short-term storage of European eel sperm under air-limited conditions

P>In order to study different storage conditions, dilution ratios and additives for fresh European eel sperm were assayed to determinate the optimum conditions for short-term storage. Two experiments were conducted, analysing the sperm motility and its viability at different times of incubation (1, 4, 7, 11 and 14 days). In the first part of the work, 19 pooled samples were used, and seven in the second experiment. Firstly, exposure to atmospheric and air-limited conditions were compared, registering the highest motility under air-limited conditions, showing no differences to the performance of fresh sperm samples until 96 h of incubation. Also, two different dilutions were checked, with ratios 1 : 10 and 1 : 50, with the latter obtaining better results. A second experiment was performed trying to improve the results obtained in the first experiment. Using air-limited condition and 1 : 50 dilution ratio, the effect of different additives (foetal bovine serum, FBS; N-Tris(hydroxymethyl) methyl-3-aminopropanesulfonic Acid, TAPS; bovine serum albumin, BSA; Glucose) were evaluated. The sperm diluted in the media containing glucose provided motilities without difference in comparison to fresh samples during first week of incubation. At 7 days of storage, the medium containing 300 mm glucose was the only one causing higher motility (77.9 +/- 2.5%) in comparison with control medium (50.1 +/- 11.5%), demonstrating that the sugar addition was positive to preserve the sperm movement. In conclusion, a new method of eel sperm preservation has been developed, using air-limited conditions, 1 : 50 dilution ratio and glucose as an additive, which provided motilities without significant differences until 7 days of incubation.