In Vivo and In Vitro Gastric Emptying of Protein Fractions of Milk Replacers Containing Whey Proteins

¹ Institut National de la Recherche Agronomique Rennes, France 35042
² Agriculture Canada, Lennoxville, PQ, Canada J1M 1Z3
³ Université Laval Ste Foy, PQ, Canada G1K 7P4
⁴ Université Laval, Ste Foy, PQ, Canada G1K 7P4
⁵ Institut National de la Recherche Agronomique Rennes, France
⁶ Institut National de la Recherche Agronomique Jouy en Josas, France 78350

In vivo and in vitro gastric emptying of protein fractions of three milk replacers containing either milk protein (control), a mixture (50:50 on a CP basis) of milk protein and native whey protein concentrate, or a mixture (50:50 on a CP basis) of milk protein and heated whey protein concentrate was studied. In vivo gastric emptying was measured in three preruminant calves fitted with reentrant duodenal cannulas and used in a 3 x 3 Latin square design. In vitro gastric emptying was determined after enzymatic digestion in an artificial stomach. In vivo and in vitro flow rates of protein N (12% TCA-insoluble N) and total N were higher for milk replacers containing whey proteins than for control. Gastric emptying of NPN (12% TCA-soluble N) was slightly higher for diets containing whey proteins than for that containing milk proteins. Gastric emptying of all protein fractions was similar for the two milk replacers containing whey proteins. In vivo and in vitro results were significantly correlated, suggesting that the in vitro method reproduced conditions for proteolysis and could be used to predict gastric digestion of protein fractions.

Key Words: artificial stomach • calf • gastric emptying • milk replacer

Submitted on June 24, 1991
Accepted on September 12, 1991