The digestibility coefficients and the true digestible amino acids content of soybean and soybean by-products were determined using cecectomized adult cockerels. Each one of the 8 feedstuffs evaluated was fed to six cockerels, consuming 15 g at 8:00 A.M. and 15 g at 16:00h P.M., after 24 hours fasting. Simultaneously, six cockerels were fasted to determine metabolic and endogenous losses. After determination of the digestibility coefficients and calculation of the digestible amino acids, prediction equations were simulated to predict the soybean and soybean byproducts total and digestible composition in lysine (LYS), methionine (MET), methionine plus cystine (Met + Cys), threonine (THR) and arginine (ARG), as a function of the chemical composition (crude protein - CP, crude fiber - CF, ether extract - EE and ash). The average amino acids digestibility coefficient (essential and non essential) of soybean meal samples (1, 2, 3, 4 and texturized), full fat soybean Jet Sploder, toasted and micronized were 92,78 and 90,76; 92,66 and 89,70; 93,75 and 91,26; 93,32 and 90,12; 91,55 and 89,08; 94,80 and 92,34; 94,61 and 91,47; 93,20 and 90,47%, respetively. The prediction equations were adjusted with higher R² values higher than 91%, and crude protein showed high positive correlation. The equations LYS = -0.32161 + 0.06731PB (R² = 0.99); MET = 0.02263 + 0.01323PB (R² = 0.96); Met+Cys = 0.078949 + 0.02563PB (R² = 0.94); THR = 0.20930 + 0.03533PB (R² = 0.95); ARG = -0.39589 + 0.08022PB (R² = 0.98) e LYS = -0.29472 + 0.06319PB (R² = 0.98); MET = 0.02884 + 0.01228PB (R² = 0.93); Met+Cys = 0.08974 + 0.02220PB (R² = 0.91); THR = 0.15813 + 0.03235PB (R² = 0.95) e ARG = -0.32129 + 0.07681PB (R² = 0.96), can be used to predict the total and digestible amino acids content of soybean and byproducts, respectively.
digestible amino acids; cecectomized cockerels; soybean; prediction equations
