Response of pancreatic secretions to feeding diets with low and high levels of soybean trypsin inhibitors in growing pigs

Studies were carried out to determine the effect of soybean trypsin inhibitors (SBTI) on exocrine pancreatic secretions in growing pigs. Six barrows with an average initial body weight (BW) of 27.1 +/- 1.4 kg were fitted with permanent pancreatic re-entrant cannulas and fed two diets according to a crossover design. Two maize starch-based diets were formulated to contain 200 g kg(-1) crude protein from either Nutrisoy (food grade defatted soy flour) or autoclaved Nutrisoy. The concentrations of SBTI in Nutrisoy and autoclaved Nutrisoy diets were 13.4 and 3.0 g kg(-1), respectively. The experiment consisted of two periods of 9 days each. The average BW at the start of the first and second experimental periods was 33.5 +/- 2.7 and 37.2 +/- 3.7 kg, respectively. The average BW at the conclusion of the experiment was 41.8 +/- 3.9 kg. The volume of pancreatic secretion was higher (P < 0.01) when the Nutrisoy, as opposed to the autoclaved Nutrisoy diet was fed (3804 vs 2634 ml (24 h)(-1)). The concentration of nitrogen and protein and specific activities (units litre(-1)) of amylase, chymotrypsin and trypsin were lower (P < 0.05) in pancreatic juice of pigs fed the Nutrisoy diet. There were no differences (P > 0.05) in the total secretions of nitrogen (g (24 h)(-1)) and total activities (units (24 h)(-1)) of amylase, lipase, chymotrypsin and trypsin in pancreatic juice of pigs fed the Nutrisoy and autoclaved Nutrisoy diets. However, the total secretion of protein was slightly higher (25.7 vs 22.8 g (24 h)(-1); P < 0.05) in pancreatic juice of pigs fed the autoclaved Nutrisoy diet, which corresponded with the increase in the secretion of protein-bound amino acids. There was also an increase in the total secretion of free amino acids in pancreatic juice. These studies show no effect of SBTI on the total enzyme activities in pancreatic juice of growing pigs. (C) 1998 SCI.