In Vivo and In Vitro Gastric Emptying of Milk Replacers Containing Soybean Proteins

¹ Institut National de la Recherche Agronomique Rennes, France 35042
² Agriculture Canada, La Pocatiére, PQ, Canada G0R 1Z0
³ Agriculture Canada, Ottawa, ON, Canada K1A 0C6
⁴ Université Laval, Ste Foy, PQ, Canada G1K 7P4
⁵ Institut National de la Recherche Agronomique, Rennes, France 35042
⁶ Institut National de la Recherche Agronomique, Jouy en Josas, France 78350

Gastric digestion of three milk replacers for which protein was provided either exclusively by milk powder or partially (50%) by heated soybean flour or soybean protein concentrate was studied in vivo and in vitro. In vivo gastric emptying of protein fractions of the diets was measured in six preruminant calves fitted with reentrant duodenal cannulas and used in a double 3 x 3 Latin square design. In vitro gastric emptying was studied after hydrochloric acid and rennet digestion in an artificial stomach. In vivo and in vitro flow rates of 12% TCA-insoluble N and total N were higher for the soybean diets than for the milk protein diet, indicating that the incorporation of soybean protein prevented casein from clotting. Because of this faster gastric emptying, proteolysis in the stomach was reduced. However, gastric emptying of NPN (12% TCA-soluble N) was significantly decreased only in vitro. No difference existed between the two milk replacers containing either soybean flour or soybean protein concentrate. In vivo and in vitro results were correlated, suggesting that the in vitro method could be used to predict gastric digestion of protein fractions in vivo.

Key Words: artificial stomach • preruminant calf • gastric emptying • soybean

Submitted on January 21, 1993
Accepted on September 3, 1993