Plant-Based Protein as a Partial Fishmeal Replacement in Catla catla: Effects on Growth and Health

Abstract

With the high cost and scarcity of fishmeal, finding sustainable alternatives for aquaculture feed protein sources has become more important than ever. This experiment was conducted to analyze the impact of substitution of fishmeal by plant-based protein source in the feeding of Catla catla. Five isonitrogenous and isolipidic diets with increasing level of fishmeal substitution were used in the experiment; namely FM100 (0%), FM75 (25%), FM50 (50%), FM25 (75%), and FM0 (100%). The experiment was conducted for 12 weeks using the experimental diets in controlled culture system. It was revealed through this experiment that growth and physiological indices were significantly affected due to dietary treatments (P < 0.05). The fish fed on FM50 diet showed better final body weight (53.7 g), weight gain (43.7 g), specific growth rate (2.74% day⁻¹), protein efficiency ratio (2.21), and survival rate (98%) with lowest feed conversion ratio (1.41). The indices related to hematological parameters including hemoglobin, hematocrit, red blood cell count, and white blood cell count were significantly improved in the fish fed on FM50 diet. In the same manner, the levels of serum total protein, albumin, and globulin were elevated, but glucose, cholesterol, triglycerides, ALT, and AST levels did not exceed normal physiological values. The antioxidant enzymes (SOD, CAT, and GPx) activity, immune response of innate immunity, and digestive enzymes activity increased significantly in the FM50 group and at the same time reduced lipid peroxidation. According to histopathological results, there was an improvement of the intestinal and liver structure, and the results of the expression of genes involved in growth and antioxidative processes were increased. Conversely, the full substitution of fishmeal had an adverse effect on growth, metabolism, antioxidation, and immunity. Thus, it was proved that substitution of up to 50% of fishmeal by plant proteins can improve growth performance and health status of Catla catla.