The true digestibility coefficients and the values of true digestible amino acids of whole toasted soybean, micronized soybean and five soybean meals samples were determined. The forced feeding method was used with cecectomized adult cockerels. A total of 24 adult Leghorn cockerels averaging 2348 ± 165 g were used. Each feedstuff was fed to six cockerels, with the cockerel the experimental unit, in two replicates in the time. A total of 30 g of the tested feedstuff was forced fed to cockerel, in a total of six replicates and the excreta collection was realized during 48 h after forced fed. Simultaneously six cockerels were maintained in fasting to determine the metabolic and endogenous losses. The values of total amino acids were about 10% lower than those presented by the literature and the true digestibility coefficients of the essential and non-essential amino acids of those feeds were 91.3 and 90.6%, respectively. Among essential amino acids of soybean meals, isoleucine was the one with lower average digestibility (86.4%) and phenylalanine, that which presented the higher digestibility (95.5%). When estimated by the prediction equations, it was observed that, in general, the equations proposed in the international literature did not fit well the content of amino acids of the feedstuffs of the soybean group. However, except for the lysine and the methionine, the equations proposed in the national literature made good prediction in comparison to the analyzed values.
forced feeding; digestibility; micronized soybean; soybean meal; whole toasted soybean
