Pancreatic mass, cellularity, and α-amylase and trypsin activity in feedlot steers fed diets with increasing corn silage inclusion

Twenty-four yearling beef steers (initial BW = 535 ± 5.0 kg), predominately of Angus breeding, were used in a randomized complete block design to determine the effect of dietary inclusion of corn silage on pancreatic cellularity, mass, and α-amylase and trypsin activity. Using calan gates, steers were individually fed diets containing 20, 40, 60, or 80% corn silage (DM basis) with the rest of the diet made up of concentrate. Diets were formulated to maintain a constant CP:ME (g Mcal -1 ) and were fed at 2.1 × NE m requirement. After 28 d on treatment, the two heaviest steers from each treatment were slaughtered per week and pancreata collected. Pancreatic weight (g and g kg -1 BW) and content (kU and U kg -1 BW) of α-amylase activity did not differ among dietary treatments. Concentration (U g -1 ) of pancreatic α-amylase decreased (P = 0.03) with increasing corn silage inclusion. Pancreatic DNA and RNA content (g and mg kg -1 BW) increased linearly (P ≤ 0.04) with increasing corn silage inclusion. The content of pancreatic trypsin activity responded cubically (P = 0.03). These data indicate that increasing corn silage inclusion does not influence total pancreatic α-amylase activity and that cell number may influence pancreatic α-amylase concentration. Key words: Beef cattle, pancreas, α-amylase, trypsin, forage, concentrate