Effect of egg yolk on the spermatozoa quality of the botia chromobotia macracanthus (Bleeker, 1852) (cyprinidae) after short-term cryopreservation

The egg yolk effect combined with 10% of methanol to preserve botia, Chromobotia macracanthus spermatozoa for 24 hours in liquid nitrogen has been studied. The concentration of egg yolk used in this study were, 0%, 5%, 7%, 9%, 11%, 13%, 15%, and 17%, respectively. As the positive control, the synthetic cryoprotectant carboxy methyl cellulose (CMC) was used. The sperms were diluted with the combination of 10% methanol, glucose extender and egg yolk (1 part of sample + 4 parts of solvent) and were equilibrated for 2 hours at 4°C before freezed for 24 hours in liquid nitrogen. After freezed, sample (sperms) were thawed for 13 sec at 40°C. Spermatozoa viability, motility, and abnormality, were then observed. Ten percent of methanol combined with 15% of egg yolk could preserve spermatozoa which maintain either sperm motility (96.43±1.49%) or sperm viability (84.25±1.26%) and reduced the abnormality up to 11.50±1.29%, respectively. Besides, the combination of 15% of egg yolk and 10% of methanol showed the highest fertility rate (50.64±4.37%).