Apparent ileal digestibility of protein and amino acids in protein feedstuffs and trypsin activity in the small intestine in broiler chickens

Coefficients of ileal apparent digestibility (CIAD) for crude protein (CP) and amino acids in five protein feedstuffs: corn distillers dried grains with solubles (DDGS), raw full-fat soybean (RFFSB), extruded full fat soybean (EFFSB), soybean meal (SBM), and rapeseed meal (RSM) were determined using 5-week-old male broiler chickens. Trypsin activity in digesta in the ileum and jejunum were also measured. CIAD of CP was the highest in SBM (0.73). The lowest (P < 0.05) CIAD of CP was determined for RFFSB (0.45). There was no significant difference in CIAD of CP between RSM (0.61) and DDGS (0.62). The CIAD values for all essential amino acids except Lys (0.52) were the lowest in RFFSB (P < 0.05). The CIAD of Lys was the lowest in DDGS (0.39, P < 0.05). The CIAD for all essential amino acids was the highest in SBM (P < 0.05). There was no significant difference between EFFSB and SBM (P > 0.05) in CIAD of Leu (0.71, 0.73), His (0.66, 0.69), Lys (0.70, 0.77), Met (0.74, 0.80), Thr (0.60, 0.62), and Val (0.65, 0.67). Both the feedstuff and the intestinal region and their interaction had a significant (P < 0.01) effect on trypsin activity. The CIAD of CP and amino acids were very high and comparable both in EFFSB and SBM. The CIAD values for CP and amino acids in DDGS and RSM were lower than in SBM, but they seemed to be comparable to each other.