Enriching Artemia with n-3HUFA modulated growth, survival, digestive enzymes, body composition and stress resistance in giant trevally (Caranx ignobilis) larvae

Abstract

High mortality of marine fish larvae during live-prey feeding and metamorphosis is a bottleneck in commercial hatchery production. This study investigated the effects of dietary highly unsaturated fatty acids (HUFA) used to enrich Artemia on the growth, survival, digestive enzyme activity, proximate composition and stress resistance of giant trevally (Caranx ignobilis) larvae. The 13 days after hatching larvae were fed Artemia enriched with a rich HUFA emulsion at five levels (0, 150, 300, 450 and 600 mg/L) for 28 days. The results indicated that enriched HUFA Artemia significantly increased the survival of giant trevally larvae. Larval growth tended to increase in fish fed enriched Artemia, with the highest weight and length obtained in a dietary n-3HUFA of 19.03% total fatty acids (TFA). There were no differences in protein and moisture of the larvae fed experimental diets, while lipid content was significantly increased in fish fed n-3HUFA enrichment at 150, 300 and 450 mg/L. The activities of pepsin and trypsin remained unchanged in larvae fed enriched HUFA diets, but significantly increased compared to the unenriched Artemia group (P < 0.05). Activity of chymotrypsin increased to a peak at 300 mg/L enrichment and was significantly reduced in the 450 and 600 mg/L groups. The mortalities of the larvae after the salinity test were significantly reduced in the 300, 450 and 600 mg/L groups. Overall, dietary n-3HUFA requirements to maximize final body weight and survival for giant trevally during Artemia feeding were estimated at 15.63% and 22.67% TFA, respectively based on polynomial regression analysis.