Effect of Isolated Soybean Protein and Casein on the Gastric pH and Rate of Passage of Food Residues in Baby Pigs

Publisher Website
Google Scholar
Abstract
Young pigs 4 to 10 weeks of age were used to study the effect of purified diets containing isolated soybean protein or casein on the pH of stomach contents and the rate of passage of food residues through the gastrointestinal tract. The pH of stomach contents as measured in vivo by means of a gastric fistula was affected by the diet fed and by age. In 4-week old pigs fed a liquid diet containing casein the pH dropped from 5.6 five minutes after feeding to 1.7 two hours after feeding, whereas in pigs of the same age fed a soybean protein diet approximately four hours were required for the pH to return to the pre-feeding level. In 8-week old pigs fed dry diets the pH of stomach contents returned to the pre-feeding level within two hours with both casein and soybean protein. The average pH of stomach contents as measured in vivo just prior to slaughter was 1.6, while that obtained by measuring stomach contents obtained from the same pigs just after slaughter was 3.6, indicating that the stomach fluid may be contaminated at the time of slaughter with saliva and/or duodenal contents. The rate of passage of food residues through the GI tract at 4 weeks of age as estimated by use of a ferric oxide marker was 14–24 hours in pigs fed soybean protein as compared to 36 to 48 hours in those fed casein. In 8-week old pigs the marker appeared in the feces 40 to 50 hours after feeding with both diets. The possible relationship between gastric pH and emptying of the stomach is discussed. Copyright © . .