Apparent digestibility coefficient(ADC)of dry matter,protein and energy of soybean meal,rapeseed meal,meat and bone meal and feather meal for Nile tilapia,Oreochromis niloticus(body weight 101 g)were measured in an indoor experiment.The test diets were formulated to contain 70% the reference diet and 30% the tested ingredient.Chromic oxide(Cr2O3)was added at 1% in the reference diet as an inert marker.The fish were fed the reference diet for three days,and then fed the test diets in following four days ever...