Effects of Substituting Soybean Meal by Unprocessed and Processed Peanut Cake Meal on the Growth, Body Composition and Survival of Tilapia (Oreochromis niloticus)

Abstract

An 8-week feeding trial was conducted to investigate the effects of replacing soybean meal by unprocessed and processed peanut cake meal on the growth, body composition and survival of Nile tilapia fry. Five types of feed were produced: diet 1 containing unprocessed peanut meal (natural NPM), diet 2 toasted peanut meal (toasted TPM), diet 3 fermented peanut meal (fermented FPM), diet 4 steamed peanut meal (steamed SPM) and diet 5 containing soybean meal (SBM). For the diet containing FPM, the fermentation of the mill mixed with yeast lasted 7 days anaerobically. The diet containing SPM was formulated with a steam-treated cake on a couscous steamer held on a kettle. The diet made with TPM underwent heat treatment on a stove. The remaining part of the cake NPM did not undergo any transformation. The experiment was conducted in an open system at the University of Cheikh Anta Diop and lasted nearly for two months. The fish were first subjected to acclimatisation phase prior to the initiation of the trial. The five treatment diets were triplicated and the stocking density was 15 fish per tank with a total of 225 fry with an initial average weight of 0.13 g. The fish were raised in plastic tanks of 50L each and fed three times a day (9 a.m, 1p.m and 5 p.m) at a feeding rate of 8% and 3% of their body weight during the 1^st, 2^nd to 3^rd and 4^th 2 weeks respectively. The temperature and dissolved oxygen were monitored in the morning and evening and the culture units were cleaned, siphoned and refilled with water at two third of their capacity prior to the feeding. The results of this study indicated that dietary NPM and TPM could replace SBM without a negative impact on the growth of tilapia. The FCR of the fish fed the diet containing NPM, SPM, TPM are not significantly different with FCR of those fed SBM. There were effects on the body composition of the fish fed diets containing the substitution of soybean meal with processed peanunut cake. The survival rate varied from 93 to 100%. The results of the analysis of the aflatoxin level in the four types of feed containing peanut meal showed that the heat treatment had no effect on the aflatoxin content. The substitution of soybean meal with natural and toasted peanut cake has no adverse effect on growth and feed efficiency of Nile tilapia fry. The authors suggested to use natural or toasted peanut cake for better growth.