Evaluation of plant and animal source proteins for replacement of fish meal in practical diets for the largemouth bass Micropterus salmoides

Abstract Two feeding trials were conducted with juvenile largemouth bass Micropterus salmoides to evaluate alternative plant and animal source proteins for their ability to replace fi sh meal in practical diets. The fi rst trial was designed to identify the most promising candidates. The second trial was conducted to evaluate how much of the fi sh meal could be replaced by those candidates. In Study 1, feed-trained largemouth bass (3.1 ± 0.7 g) were randomly stocked into 18 114-L glass aquaria at 25 fi sh per aquarium. Fish were fed one of six experimental diets, each containing approximately 38% crude protein and 10% crude lipid, to apparent satiation twice daily. The control diet (CTL) contained 30% fi sh meal and 34.5% soybean meal. Diets 2-6 each contained 15% fi sh meal and at least 34.5% soybean meal with the remainder of the protein made up of either meat and bone meal (MBM), soybean meal (SBM), poultry by-product meal (PBM), a 50/50 mixture of blood meal and corn gluten meal (BM/CG), or 50/50 mixture of hydrolyzed feather meal and soybean meal (FM/SBM). There were three replicate aquaria per dietary treatment. After 12 wk, there was no signifi cant difference (P > 0.05) among treatments in survival which averaged 92% overall. Only fi sh fed the PBM or BM/CG diets had average individual weights and feed conversion effi ciencies that were not signifi cantly different (P > 0.05) from the control diet (CTL). In Study 2, the formulation of the control diet (CTL) remained the same. Based on their performance in the fi rst trial, PBM and BM/CG were chosen to now replace 75 or 100% of the fi sh meal. Fish were stocked at an average weight of 6.9 ± 1.7 g. After 11 wk, fi sh fed diets containing the BM/CG mixture at both levels were signifi cantly smaller (P ≤ 0.05) than fi sh fed other diets and at 100% replacement survival was reduced. Fish fed diets containing poultry meal as the primary protein source performed as well as those fed the control diet (CTL). It appears that PBM can completely replace fi sh meal in diets for juvenile largemouth bass without adverse effects on growth, feed effi ciency, or body composition