Use of borage oil in rotifer production and Artemia enrichment: effect on growth and survival of turbot ( Scophthalmus maximus) larvae

Abstract

Three oils were used together with baker's yeast to enrich rotifers (long-term enrichment) and Artemia (24-h enrichment). These oils were: (A) cod liver oil, (B) an n−3HUFA concentrate, (C) a mixture (2:1) of the same n−3HUFA concentrate and borage oil. The n−3 concentrate (B) induced higher n−3HUFA content in rotifers and Artemia than the other oils. Borage oil supplied linoleic acid and γ-linolenic acid (18:3 n−6) in oil C. Rotifers fed oil C contained 2% 18:3 n−6 and 3% dihomo- γ-linolenic acid (20:3 n−6), but the arachidonic acid content was not different from the other treatments. No sign of elongation of 18:3 n−6 to 20:3 n−6 was observed in Artemia enriched with oil C. These live food organisms were compared as food for turbot larvae, at first feeding, growth of turbot larvae was lower when they were fed with the rotifers produced with oil B compared to the other treatments. Subsequently, when larvae were fed on enriched Artemia, the growth was influenced by larval density and dietary n−3HUFA. Treatment C gave the best results in terms of survival, with less variation within replicates than the other treatments. These results suggest that n−6 fatty acids and probably dihomo- γ-linolenic acid have a beneficial effect on survival of larvae during the critical early life stages.