Contamination of palm kernel meal with Aspergillus flavus affects its nutritive value in pelleted feed for tilapia, Oreochromis mossambicus

An assessment of the nutritive value of palm kernel meal (PKM) and aflatoxi n-contaminated PKM (obtained by fermenting PKM with Aspergillus flavus) as a dietary ingredient in pelleted feed for tilapia, Oreochromis mossambicus Peters, was carried out in a 12-week feeding trial. Seven isonitrogenous (4 0%, crude protein) and isoenergetic (15.1 kJ g(-1)) practical diets were fo rmulated and fed close to apparent satiation to triplicate groups of 12 fis h (mean initial weight 8.4 +/- 0.1 g). The control diet contained 30% fish meal and 10% soybean meal (SBM) proteins. Four other experimental diets con taining 20%, and 50% of the SBM protein replaced by either PKM or fermented PKM, respectively, were formulated. Two additional diets containing either PKM or fermented PKM supplemented with a commercial aflatoxin adsorber (0. 5%, Sorbatox(TM) were also formulated. Measured aflatoxin B-1 levels in the fermented PKM-based diets ranged from 75 to 100 mug kg(-1) diet. The growt h performance and feed utilization efficiency of tilapia fed fermented PKM- based diets were significantly lower than in fish fed the control diet at a ll inclusion levels (P < 0.05). Despite a small reduction, weight gains of tilapia fed PKM-based diets were not significantly different compared with fish fed the control diet. The addition of 0.5%) Sorbatox did not produce a ny beneficial or negative effects to the growth of tilapia. Under the dieta ry conditions of the present experiment, it was concluded that PKM can subs titute up to 50% SBM in practical diets for O. mossambicus without much adv erse effect to fish growth. However, when PKM was contaminated with A. flav us, its incorporation into tilapia diets resulted in growth depression as a result of decreased diet digestibility and also possibly because of the pr esence of anti-nutrients found in the contaminated PKM.