Development of feeds for juvenile Atlantic bluefin tuna (Thunnus thynnus, L): effect of lipid level and source

Abstract

In conclusion, the present study suggests that ABT juveniles can be grown on inert extruded dry feeds that result in good fish growth and accumulation of the health-promoting fatty acid DHA. Furthermore, a blend of VO and KO could be used as the dietary lipid source up to a dietary lipid level of 15 % without affecting fish performance. The expression of lipid metabolism genes in ABT liver showed a different response to dietary lipid level/fatty acid profile, consistent with previous data indicating limited n-3 LC-PUFA biosynthetic capability in ABT. However, gene expression showed some differences between the two trials, which highlight how the genetic background of different batches of ABT juveniles could affect the regulation of metabolic gene expression and thus be a factor in weaning success. The expression of antioxidant enzymes was also altered by diet, related to dietary contents of antioxidant nutrients. Thus, further studies are required in order to fully elucidate the lipid and fatty acid requirements of this iconic species in relation to dietary sources and production costs