Effect of L-cysteine on chilled carp (Cyprinus carpio) Semen Qualities

The aim of the present study was to study the effects of L-cysteine on chilled carp (Cyprinus carpio) semen qualities. Pooled semen samples were prepared from eight fish, and divided into five groups according to the concentrations of L-cysteine as follows: 0 (T1), 0.5 (T2), 1.0 (T3), 1.5 (T4) and 2 (T5) mM. The sperm motility, duration of sperm motility and sperm viability were evaluated at 0, 12, 24, 48, 72 hours after chilled storage. Comparing between treatment and control groups, the percentage of sperm motility, duration of sperm motility and the percentage of sperm viability in the treatment groups were significantly higher than the control group (p < 0.05). Considering over a period of time after chilled storage, modified Kurokura's extender plus L-cysteine groups were able to maintain carp semen qualities (motility, duration of motility and viability) up to 24 hour. Comparing all concentrations of L-cysteine, at 24 hour after chilled storage, the optimal concentration of L-cysteine was found at 1 mM. In conclusion, supplementation of L-cysteine at 1 mMol in modified Kurokura's extender can be recommended for carp semen chilled storage.