Apparent and true ileal digestibilities of amino acids in newly-weaned piglets fed diets with protease-treated soybean meal

Twelve piglets, fitted with a modified post valve T-caecum cannula on d 14, 15 and 16 after birth, were weaned on d 20. Treatments consisted of soybean meal which was untreated (SBM), incubated (1:2 wt/vol water adjusted to pH 4.5, for 16 h at 50 degrees C; CI-SBM), sprayed with protease (1 mu L/g of soybean meal; PS-SBM) and incubated with protease (PI-SBM). Apparent digestibilities (%) of the indispensable amino acids were similar (P > 0.05), ranging from 68.5, 68.7, 60.5 and 68.1 (threonine) to 83.5, 83.3, 78.7 and 84.7 (arginine) for SBM, CI-SBM, PS-SBM and PI-SBM, respectively. True digestibilities (%) were usually similar (P > 0.05) between guanidinated SBM, CI-SBM and PS-SBM but lower (P < 0.05) for PI-SBM due to losses of amino acids from soybean meal. Apparent digestibilities were usually lower (P < 0.05) in Period 1 (1 to 9 d after weaning) than in Period 2 (10 to 18 d after weaning). True digestibilities were similar (P > 0.05).