Effects of Fortification of Nutrients to Female Broodstock by Diet alone and by both Diet and Direct Injection on the Egg Quality of Japanese Eel Anguilla japonica

摘要

This study aimed at improving the egg quality of Japanese eel Anguilla japonica preliminary by evaluating several nutritional approaches. Various nutrients including vitamins C and E were fortified (1)in a female broodstock diet alone before artificial maturation and (2) in broodstock diets and by injection to the broodstock during artincial maturation. The quality of eggs obtained was compared to that from unfortified broodstock. The best hatching rate and survival at 8 days post hatching were obtained in the group with combined fortification by the diet CEK (supplemented with vitamins, frozen knll, astaxanthin, lecitnin and taurine) and by the vitamins and astaxanthin (CEA) injection, followed by the group with combined fortification by the diet CE (supplemented with vitamins alone) and by the CEA injection. The egg quality of the group with dietary fortification (diet CEK) alone was not significantly different from the unsupplemented and uninjected group. These results show that fortification ofnutrients including vitamins C and E to female broodstock in the diet before induction of maturation and by injection during artificial maturation improves the egg quality of Japanese eel. This study also suggests that nutrient injection to female eel broodstock is essential for the improvement of egg quality.