Study on replacement of fish meal by two plant protein mixtures in diets for largemouth bass (Micropterus salmoides)

Abstract:

Four isonitrogenous and isoenergetic diets were formulated to evaluate the feasibility of partial replacement of fish meal by two plant protein mixtures (composed of dehulled soybean meal and corn gluten meal or rice protein meal, respectively) in 45% fish meal diet and 30% fish meal diets for largemouth bass (Micropterus salmoides). Fish[initial body weight (58.69±0.07) g] were fed over 53 days. The results suggested that there were no significant differences in survival rate among all treatments (P>0.05). 30% fish meal diets-fed fish showed higher final body weight, specific growth rate and feed intake than 45% fish meal diets-fed fish (P<0.05), while feed efficiency ratio, protein efficiency ratio, protein digestibility and total amino acid digestibility showed no significant differences between 30% fish meal diets-fed fish and 45% fish meal diets-fed fish (P>0.05). The fish fed corn gluten meal diets had a significantly higher feed efficiency ratio and protein efficiency rate than fish fed rice protein meal diets (P<0.05), however, feed intake with fish fed corn gluten meal diets was significantly lower than fish fed rice protein meal diets (P<0.05). There were no significant differences in concentrations of crude protein, crude lipid, moisture and ash of the whole body and muscle among all the treatments (P>0.05). Fish fed 30% fish meal diets had significantly higher serum lysozyme activity and serum protein content than fish fed 45% fish meal diets (P<0.05), but no significances occurred between corn gluten meal diets-fed fish and rice protein meal diets-fed fish (P>0.05). No significant differences in red blood cell count and hematocrit among all the treatments were observed (P>0.05). It can be concluded from this study that in the diet for largemouth bass fish meal inclusion level can be replaced from 45% to 30% with the mixtures composed of dehulled soybean meal and corn gluten meal or rice protein meal. The mixture containing corn gluten meal has a better substitution effect than the mixture containing rice protein meal.