Vitamin B 6 in Atlantic halibut, Hippoglossus hippoglossus—endogenous utilization and retention in larvae fed natural zooplankton

Abstract

A single batch of Atlantic halibut larvae was reared in floating plastic enclosures, offered natural plankton collected from a lagoon and sampled regularly for measurements of vitamin B 6. At hatching individual whole larvae contained 9.0 ± 0.2 ng of vitamin B 6, of which 95% was present in the yolk. At the onset of first feeding 50% of the vitamin B 6 present in the yolk at hatching had been transferred to the larval body. There was a relatively constant weight specific content of vitamin B 6 in the larval body from hatching until first feeding at 206 Day degrees post hatch (D°PH) at 3.5 ± 0.3 μg g −1 DW. During this period there was a net decline of 2.3 ng vitamin B 6 per larvae. After onset of first feeding the vitamin B 6 content in the larvae continued to decline and reached its lowest level at 300 D°PH with 5.0 ng individual −1. With continued development the feeding larvae increased their content of vitamin B 6. However, in weight specific terms the content of vitamin B 6 in halibut larvae above a DW weight of 5 mg stabilized at 5.1 ± 0.2 μg g −1 DW, about the same value as the plankton feed offered. The data in this study represents vitamin B 6 status in halibut larvae and planktonic prey in semi-intensive culture systems with a high outcome of metamorphosed larvae and may therefore serve as a basis for feed formulation in intensive farming of Atlantic halibut.