Vitamin content and quality of eggs produced by broodstock injected with vitamins C and E during artificial maturation in Japanese eel Anguilla japonica

This study was conducted to investigate the effects of injection of vitamins C (VC) and E (VE) into broodstock on the vitamin levels of broodstock and eggs and subsequent egg and larval quality in the Japanese eel. Broodstock were allotted to one of three groups; control group, injected with physiological saline; early group, injected with vitamins during the early part of maturation (1st-3rd weeks after initiation of maturation induction); later group, injected with vitamins during the later part of maturation (4th-6th weeks after initiation of maturation induction). Broodstock were injected with an emulsion of VC and VE at the same time as an injection of salmon pituitary extract during the induction of maturation. The emulsion was prepared by mixing α-tocopherol, sodium ascorbate, an emulsifier, and water just before injection. The levels of both vitamins in eggs and broodstock increased following vitamin injection. However, the accumulation of vitamins in broodstock and eggs was higher for VE than for VC. Hatching rate, survival and normality of larvae increased with vitamin treatments. The results of this study showed that VC and VE injection into broodstock during artificial maturation increases the vitamin content of eggs and can improve egg quality in Japanese eel.