Short-term cold storage of the semen of rainbow troutOncorhynchus mykiss(Walbaum, 1792) incorporating DMSO in the sperm diluent. Effects on motility and fertilizing capacity

This work evaluated the incorporation of dimethyl sulphoxide (DMSO) into the medium used for storing rainbow trout semen at 4°C for 13 days. The treatments used were: fresh semen as control (C); semen stored without dilution (T1); semen diluted in saline solution (0.2% KCl and 0.7% NaCl) (T2); T2 + DMSO 1% (T3); T2 + DMSO 2.5% (T4) and T2 + DMSO 5% (T5). Sperm motility (level and duration) and fertility were evaluated in all the treatments. The results show that at day 3, all the treatments maintained level 3 motility. After 5 days in storage, only T4 and T5 fell to level 2 motility. The maximum duration of flagellar activity was in T3 with 70.0 ± 2.14 s, and the minimum in T4 with 51.73 ± 0.29 s. At day 7, the fertility of T3 and T4 was maintained with no statistically significant differences from T2 (96.6 ± 2.5%), however, the fertility of T5 was 53.2 ± 11.8%. At day 13 the fertility of T3, the only treatment which remained fertile, was 68.8 ± 5.09%. The results show that the sperm fertility of semen stored with a low concentration of 1% DMSO is prolonged significantly.