Abstract
The influence of replacing diet fish meal LT94 (FM) with different levels of full fat soybean meal (FFSB) on growth performance and enzymes activity in stomach, hepato-pancreas and intestine were investigated for Nile tilapia Oreochromis niloticus. Four diets (D1, D2, D3 and D4) were formulated 0, 15, 20, and 20 g/100 protein of diets + DL-methionine by replacing FFSB with fish meal respectively. Proximate composition of the diets was determined. The growth of O. niloticus was significantly decreased (P<0.05) with substitution of fish meal by FFSB (D2, D3 and D4) compared to the control group (D1). The lowest weight gain (46.02 +/- 1.30 g), specific growth rate (SGR: 2.29%+/- 0.03), protein efficiency ratio (PER: 2.25 +/- 0.04) and apparent net protein utilization (ANPU: 36.37%+/- 0.29) were achieved at D4. Regression analysis did not show a significant differences (P>0.05) for proteolytic and trypsin activities in the intestine and stomach among the data of all fish groups. However, hepato-pancreas proteolytic and trypsin activities showed significant decrease (P<0.05) with increase of FFSB magnitude in the diets. Activity of amylase and lipase in hepato-pancreas, stomach and intestine displayed significant differences (P<0.05) between control group and fish of the tested diets groups. The carcass composition of fish did not exhibit a significant difference.