Use of antioxidants on rainbow trout Oncorhynchus mykiss (Walbaum, 1792) sperm diluent: effects on motility and fertilizing capability
The present investigation determined how different antioxidants incorporated into the sperm diluent for cold storage of semen affected sperm motility and spermatozoan fertility capabilities of the rainbow trout. For the evaluations, fresh semen (C) and semen that had been stored without diluents (T1) were used as control groups. The diluents were prepared using a base of UCT diluents (T2), adding grape polyphenol (0.1 g 100 mL-1) (T3), trolox C (0.1 g 100 mL-1) (T4), polyphenol (0.1 g 100 mL-1) plus trolox (0.1 g 100 mL-1) (T5), and vitamin C (0.018 g 100 mL-1) (T6). The incorporation of antioxidants into sperm diluents prolongs motility and fertility of rainbow trout semen. The results show that by day two, all of the treatments showed level 5 sperm motility. After seven days of storage, only T3 and T6 dropped to level 4 sperm motility. The duration of flagellate activity on this day was maximal for T3 with 36.87 ± 0.51 s and minimal for T6 with 29.78 ± 0.52 s. On day seven, fertility was maintained with no statistically significant differences between the control and T2 (92.80 ± 0.62%), T3 (83.66 ± 2.52%), T4 (90.46 ± 1.60%), T5 (83.57 ± 2.75%), and T6 (83.57 ± 2.30%). By days 10 and 17 of storage, the fertility of T1 was zero and that of T2 was significantly lower than the control group. On day 17, the highest percentage of fertilization was 97.38 ± 1.85% for T5 and the lowest value was 64.69 ± 3.76% for T2. The results allow concluding that the sperm viability of semen stored with different antioxidants is significantly prolonged.