A metabolism trial was conducted with the objective to determine the values of apparent metabolizable (EMA), corrected apparent (EMAn), true (EMV) and corrected true energy (EMVn) of toasted whole soybean, micronized whole soybean and five brands of soybean meal through the forced feeding method with adult roosters and afterwards, from the experimental results obtained, it was also validate equations to predict EMVn as related with chemical composition of the feeds. The forced feeding method was utilized, by using 24 adult Leghorn roosters with means 2.35 ± 165 g. The rooster was considered as an experimental unit and each feed was given to 6 roosters (6 replicates), two replicates in each time. Simultaneously, 6 roosters were kept in fasting for determination of the endogenous and metabolic losses. Before the experimental period, each rooster was maintained without any feed for 24 hours for emptying of the digestive tract and then forced to ingest 30 grams of the test feed. For that reason, four collections of excreta were done every 12 hours, to avoid fermentation. At the end of this period, the feeds and also the excreta were homogenized for analysis of dry matter, nitrogen and gross energy and then calculated the values of energy. The values of EMVn calculated were then contrasted with values of EMVn estimated from the prediction equations presented in the national literature for groups of feeds similar to those of the present work. The values of EMVn of the soybean meals ranged from 2531 to 2730 Kcal/kg of DM and those of toasted and micronized whole soybean were 3732 and 4027 Kcal/kg of DM, respectively. For the whole soybeans and soybean meals, the equation which best estimated the values of energy were TMEn = 2690.62 - 40.87ADF + 19.96NDF + 63.09EE. In general, the equations tested in the present work shown not good estimates of the values of EMVn, so, they are not adequate to be utilized as a predictor of energetics values in practice.
prediction of the energy; chemical composition; soy; soybean meal
