True and apparent digestibility of protein and amino acids of feed in Nile tilapia

It was determined in this work the coefficients of apparent and true digestibility of protein and amino acids of five feeds (corn, wheat bran, soybean meal, corn gluten meal, fish meal) in Nile tilapia. It was used 252 reverted Thai strain Nile tilapia (Oreochromis niloticus) in growth phase, with weight of 310 ± 9.68 g, distributed in experimental randomized blocks design, with five treatments, six replicates per treatment and seven fish per experimental unit. Each experimental diet contained a single source of protein, composed by the studied ingredients. An additional group of fish was fed protein-free diet for quantification of the endogenous fraction and determination of true digestibility coefficients. Digestibility was estimated by the indirect method by using chromium oxide at the concentration of 0.50% of the diet as a marker, performing fecal collection at every four hour interval by using decantation technique. Coefficients of apparent digestibility of the protein and amino acids are: corn, 83.57 and 82.45%; wheat bran 82.87 and 81.47%; soybean meal 91.12 and 89.41%; corn gluten meal 90.07 and 87.78%; fish meal 83.53 and 81.65% respectively. Coefficients of true digestibility of protein and the mean of the amino acids are: corn, 90.02 and 89.60%; wheat bran 89.62 and 89.14%; soybean meal 93.58 and 91.88%; corn gluten meal 92.50 and 90.34%; fish meal 86.01 and 84.27%, respectively