Partial replacement of fish meal with sunflower meal in Labeo rohitta diet through acidification and phytase supplementation

Abstract

Labeo rohita (Rohu) is one of the commercially important carp of south Asia due to its consumer’s preference. It is being traditionally cultured extensively and semi-intensively under poly and composite culture systems. Efforts are always required to introduce it in intensive culture system to achieve highest productivity. The byproducts of plant sources such as cotton seed meal, sunflower meal and corn gluten have great potential to replace expensive fish meal. The presence of antinutritional factors in these by- products chelates with nutrients which ultimately make them unavailable to the agastric and monogastric animals like fishes. The availability of nutrients of byproducts can be increased by acidification and supplementation with microbial enzymes. This present project was planned with the objective to replace the fish meal by sunflower meal in the diets of Labeo rohita. Four isocaloric and isonitrogenous diets containing different levels of fish meal and sunflower meal percentage were prepared. These diets were further supplemented with three levels of microbial phytase and citric acid each in 4×3×3 factorial experiment. This experiment was conducted in Fish Nutrition Laboratory and diets were fed to L. rohita till satiation. The samples of diets, feces and whole body were processed for various minerals and proximate analyses. Fish growth parameters such as weight gain, FCR, FCE, SGR and digestibility of nutrients were determined and compared statistically to reach to certain conclusions. The partial replacement of fish meal by sunflower meal negatively affected the growth of fish (weight gain, specific growth rate and feed conversion rate). The supplementation of 1000 FTU/kg phytase and 3% citric acid in diets significantly enhanced (p < 0.05) the growth parameters (weight gain, FCR, specific growth rate), apparent digestibility of dry matter, crude protein, crude fat, gross energy and minerals (Na, K, Ca, Fe, Mg, Mn, Zn, P). The significant improvement was observed in the dry matter, protein, fat, energy and ash contents of whole body of L. rohita. The interaction of citric acid and phytase significantly (p<0.05) affected the body composition of rohu. The cost benefit analysis revealed that 13 % fish meal based diet was economically feasible and the farmers could overcome the financial challenges by lowering the feed cost and it will also contribute in the sustainability of aquaculture.