Evaluation of Plant and Animal Protein Sources as Partial or Total Replacement of Fish Meal in Diets for Nile Tilapia Fry and Juvenile Stages

Abstract

AbstractTwo feeding trials were conducted in a closed system with Nile tilapia Oreochromis niloticus fry (mean weight, 0.10 g; experiment 1) and juveniles (mean weight, 2.84 g; experiment 2) to examine the effects of total replacement of fish meal (FM), with and without supplementation of dl‐methionine (Met) and l‐lysine (Lys), by plant protein sources. In experiment 1, fry were fed nine isoenergetic (available energy [AE] = 4.0 kcal/g of diet) and isoproteic (40% protein as fed basis) practical diets containing protein primarily from soybean meal (SBM), with and without essential Met and Lys. After 5 weeks, final individual weight (FW; g/fish) and percent weight gain (PWG) of fry fed diet 1 (control with 20% FM) was significantly higher (P < 0.05) compared with fry fed all other diets, while fry fed diet 9 containing 46% SBM and 22% feed‐grade poultry by‐product meal PBM) was significantly higher than all other diets (diets 2–8). Quantity of diet fed and percent survival did not differ significantly (P > 0.05) among all diets. In experiment 2, juveniles were fed six isoenergetic (AE = 4.0 kcal/g of diet) and isoproteic (35% protein as fed basis) practical diets containing protein primarily from SBM, soybean protein concentrate (SPC), feed‐grade PBM, or combinations of those. After 7 weeks, mean FW, PWG, and amount of diet fed for fish fed diets 1 (control with 20% FM) and 6 (with 20% SPC and 20% PBM) were significantly higher (P < 0.05) compared with juveniles fed all other diets. Feed conversion ratio (FCR) was similar among treatments, but fish fed diet 5 (with 36% SPC and 0% FM) recorded the highest FCR value. Likewise, protein efficiency ratio (PER) was similar among treatments; however, PER in juveniles fed diets 3 (with 52% SBM and 0% FM) and 5 were significantly lower than in fish fed all other diets. Overall, no significant (P > 0.05) difference was found in percent survival, which averaged 92.6% among all diets fed. These data suggest that Nile tilapia fry cannot utilize diets containing high levels (>75%) of SBM when no animal protein ingredient is added, even with supplemental Met and Lys. However, a diet containing 20% SPC and 20% feed‐grade PBM appears to be suitable for juvenile Nile tilapia, which may help reduce diet costs and allow for sustainable production.