The effect of concentration of tannin-rich bean hulls (Vicia fabaL.) on activities of lipase (EC3.1.1.3) and α-amylase (EC3.2.1.1) in digesta and pancreas and on the digestion of lipid and starch by young chicks

The effect of different concentrations of tannin-rich field-bean (Vicia faba L.) hulls at 0, 20, 50, 150 and 300 g/kg dietary inclusion on the activities of lipase (EC 3.1.1.3) and alpha-amylase (EC 3.2.1.1) in digesta and pancreas and on the digestion of lipid and starch was studied in 2-3-week-old male broiler chicks. Low dietary concentrations of tannins (20 and 50 g hulls/kg) enhanced the activity of lipase in digesta from both the jejunum and ileum, the 20 g hulls/kg effecting the greatest enhancement, but no stimulatory effect on the activity of digesta alpha-amylase was observed. High dietary concentrations of tannins (150 and 300 g hulls/kg) inhibited both lipase and alpha-amylase activities in digesta from both the jejunum and ileum, the 30 g hulls/kg causing the most inhibition. Tannins did not increase the activities of lipase or alpha-amylase in pancreatic homogenates, but at high concentrations (150 and 300 g hulls/kg) they lowered slightly the pancreatic activity of alpha-amylase. Nutrient digestion was less influenced by the concentration of tannins than digesta enzyme activities.