LIPID SUPPLEMENTATION OF CASEIN-BASED PURIFIED DIETS FOR CARP (CYPRINUS-CARPIO L) LARVAE

Common carp larvae were fed artificial diets based on purified ingredi ents (casein, casein sodium salt, casein hydrolysate, dextrin, vitamin and mineral premixes). Eight experimental diets containing two levels of peanut oil (3 or 4.5%) and supplemented with graded levels of cod liver oil (0, 1, 2 or 4%) with or without phospholipids (0 or 2%) were fed to duplicate groups for 28 days. A yeast-based diet served as the control. Survival (from 10 days onwards) and growth (as early as day 7) were significantly improved by phospholipid supplementation. By day 21, larvae fed diets without phospholipids exhibited low survival rat es (17-22%) and low mean weights (90-130 mg) compared to larvae fed ph ospholipid-supplemented diets (survival 53-83%, mean weight 180-200 mg ). Daily mortality was low in all groups between day 21 day 28. By day 28, the best casein-based diet resulted in a lower survival rate than the yeast-based control diet (78 vs. 90%). However, it supported a hi gher mean larval weight (550 vs. 330 mg). In contrast to phospholipid, dietary cod liver oil level had little effect on early survival and g rowth of the larvae. An increase in dietary cod liver oil resulted in marked changes in fatty acid composition of carp total lipid by day 28 : i.e., n-3 fatty acids increased; 20:4n-6, 20:5n-6 and 20:3n-9 decrea sed, and 22:3n-9 and 22:4n-9 disappeared. First-feeding carp larvae we re able to utilize semi-purified diets better than previously reported . During the first 2 weeks, dietary phospholipid supply seemed more cr itical for early larval survival and growth than a supply of n-3 fatty acids from cod liver oil.