Pancreatic amylase in chickens fed on soya-bean diets

Abstract

I . The action of raw and heated soya beans on pancreatic function was studied by measuring rhe amylase activity of the pancreases and intestinal contents of intact chickens and of chickens with ileostomies at fasting and after eating, before and after adaptation to heated and raw soya-bean diets, with a methionine supplement and without. 2. The concentration of amylase in the pancreases of 8-week-old chickens eating raw soya-bean diets was lower than that of those eating heated soya-bean diets. These chickens were deficient in methionine; supplementation of the raw soya-bean diet with methionine greatly increased the levels of amylase in the pancreases of such chickens; supplementation of the heated soya-bean diet with methionine increased the levels of amylase in pancreases to a smaller extent. 3. Methionine was less effective in increasing the amylase levels of the pancreases of I r-week-old chickens eating raw soya-bean diets, since at this age the deficiency of methionine was much less pronounced. 4. More amylase activity was found in intestinal contents of chickens eating raw soya-bean diets than in those eating heated soya-bean diets. 5. In vitro studies showed that fractions prepared from raw soya beans, all containing high levels of trypsin inhibitors, stabilized amylase activity despite the active proteolysis of other protein substrates in the same amylase-containing mixtures. 6. CaCl, stabilized amylase activity in vitro in unactivated and activated pancreatic juice as such, and after additions of raw soya beans or their fractions before and after autoclaving. 7. The increased levels of amylase found in the intestinal contents of the chickens eating raw soya beans may represent greater secretion of amylase activity by the pancreas, stabilization of amylase activity by the raw soya bean, or both factors. Interpretation of measurements of amylase activity in the intestinal contents of chickens eating heated or raw soya beans is uncertain. 8. The bearing of this work on current views of the nutritional value of raw and heated soya beans is discussed.Nearly 20 years ago, Chernick, Lepkovksy & Chaikoff (1948) showed that chickens eating raw soya-bean (RS) diets for varying periods of time had pancreases that were hypertrophied and contained higher levels of proteases than did pancreases from corresponding chickens that had eaten heated soya-bean (HS) diets. It was shown later by Applegarth, Furuta & Lepkovsky (1964) that the pancreases of chickens ingesting RS diets were depleted of zymogen granules to a greater extent than corresponding pancreases from chickens ingesting HS diets, indicating a greater release of pancreatic enzymes from the pancreas in response to the ingestion of the RS diets. Chemical analysis supported this histological evidence : lower levels of proteases were found in the pancreases of chickens after eating RS diets than in those of chickens after eating HS diets (Applegarth et al. 1964).The intestinal contents of chickens eating HS and RS diets were examined for corroborative evidenc...

Effect of a Soybean Diet on Enzyme Content and Ultrastructure of the Rat Exocrine Pancreas

“…It had previously been reported that the pancreatic content o f amylase decreased after feeding a raw soybean diet to rats for I week [27] while the specific activity of amylase was lowered by RSF given for 21 days to chicks [8,13] and for 7 days to rats [16], On the other hand, an increased content of amylase in response to RSF, as noted in the present study, had also been reported in rats fed egg white trypsin inhibitor for 6 [24] In conclusion, the present study has shown that feeding raw soybean flour to rats for 3 weeks increases the total protein content of the pancreas due to parallel increase of the enzyme and non-enzyme proteins.…”

Amylase Secretion by Rat Pancreas Following Prolonged Stimulation by Unheated Soybean Flour

“…It has been suggested that the enlargement of the pancreas coincides with enhanced enzyme secretion [3,7,8,10,[18][19][20], Thus, feeding unheated SBF has been reported to deplete pancreatic zymo gen granules [1] and to stimulate amylase secretion to a greater extent than heated SBF [7,16,17].…”

Trypsin inhibitor and the nutritional value of soya beans

“…Amylase, in contrast, is unstable in the intestinal contents of chickens given HS diet but is more stable in those given RS diet (Lepkovsky, Koike, Sugiura, Dimick & Furuta, 1966). Lipase is present in intestinal juice (Lepkovsky & Furuta, 1970), but the factors that govern its secretion into the intestine are unknown.…”