A blend of plant proteins as a potential fishmeal substitute in the diet of Asian seabass Lates calcarifer (Bloch-1790): Effect on growth, digestive enzymes and fatty acid composition

Abstract

A blend of plant proteins (soybean meal, groundnut oil cake, sunflower oil cake, wheat gluten meal and corn gluten meal at 4:2:1:6.5:6.5) was used to substitute fishmeal in the diet of Asian seabass, Lates calcarifer (Bloch, 1790). Five iso-nitrogenous (401.13-407.33 g kg-1) diets were prepared by substituting fishmeal at 0 (control), 25, 50, 75 and 100% (FM-R0, FM-R25, FM-R50, FM-R75 and FM-R100, respectively) using the above mix. Average final weight of the fish increased (p<0.05) by three-folds (20.77-29.99 g) after 45-days compared to their initial weight (6.09±0.25 g) in all the treatments, however, significant (p<0.05) variation was observed between the dietary treatments (p<0.002). The results indicated that 50% of dietary fishmeal can be substituted and beyond this level resulted in significant reduction of growth performance. Broken-line analysis indicated optimal fishmeal substitution as 46.7%. The highest activity of pepsin, trypsin, chymotrypsin, carboxypeptidases-A and B was observed in fish fed with diets FM-R0, FM-R25 and FM-R50. Dietary change significantly (p<0.05) influenced the carcass lipid composition of Asian seabass (p<0.001). Fatty acids like C20:4, C20:5 and C22:6 were significantly (p<0.05) low in fish carcass fed with higher levels of plant proteins (FM-R75 and FM-R100). The results concluded that dietary fishmeal level can be partially substituted using a blend of plant proteins in the diet of Asian seabass juveniles. Keywords: Asian seabass, Digestive enzymes, Fatty acid, Fishmeal, Growth, Plant proteins