APPARENT DIGESTIBILITY OF PROTEIN AND CARBOHYDRATE IN FEED INGREDIENTS FOR ADULT TILAPIA (OREOCHROMIS-AUREUS X OREOCHROMIS-NILOTICUS)

The digestibility of various diet components as protein and carbohydra te sources for adult tilapia (Oreochromis aureus x O. niloticus) was s tudied by using an inert marker in the feed and collecting the feces b y stripping. Each experimental diet consisted of a different protein a nd carbohydrate source (50%) plus 50% reference diet (50% soybean meal , 35% wheat flour, 10% soybean oil, 5% vitamins, egg yolk, guar and ch romic oxide). It was found that the apparent digestibility of protein in fish meal was 90%, in soybean meal 95%, in poultry meal 92% and in wheat flour 91%. Energy digestibility tests gave the following results : 18.09 kj/g for fish meal, 15.58 kj/g for soybean meal and 16.9 kj/g for poultry meal. The digestibility of carbohydrates was 93% for wheat flour, 81% for corn meal and 85% for barley meal. The figures for dig estible energy were 17.51 kj/g for wheat flour, 15.42 kj/g for corn me al and 14.36 kj/g for barley meal. The differences in the digestibilit y of various protein and carbohydrate sources are discussed.