Effect of Dietary Particle Size on Lesion Development and on the Contents of Various Regions of the Swine Stomach

Abstract

Two experiments were conducted to determine the relationship of dietary particle size to the formation of gastric lesions in growing-finishing swine. The first experiment consisted of 2 trials of Latin square design using fundic-pyloric fistulated pigs to study the effect of particle size of corn on pH and pepsin activity of gastric contents. With cracked corn, pepsin activity and acidity were higher in both ad libitum fed pigs and in pigs fed once daily than when fine corn was fed. The results of this experiment with fundic-pyloric samples are opposite those obtained previously in slaughter experiments ill which entire stomach contents were sampled. This apparent disagreement was shown in Experiment 2 to be due to the localized area of the stomach from which the samples were taken in Experiment 1 and a lack of mixing of gastric contents in pigs fed cracked, but not fine corn. In Experiment 2, 60 pigs were fed once daily for 7 days and on the seventh day pigs were slaughtered at the following time intervals after feed removal: 0, 4, 8, 13 and 24 hours. The stomachs were removed in a manner to minimize mixing, then frozen and divided into esophageal, fundic and pyloric regions. The contents from each region were removed, weighed and analyzed for percent moisture, pepsin activity, pH and osmolality. When cracked corn was compared to fine corn, pH was higher in the esophageal region and the opposite result was observed in the pyloric region of the stomach. After 4 hr. pepsin values in the esophageal region were much lower for pigs fed cracked corn, an effect not consistently observed in the pyloric region. For pigs fed cracked corn, percent moisture was lower in all regions and osmolality tended to be higher in the esophageal region and lower in the pyloric region. An increased rate of passage was also observed when fine corn was fed. Histamine content of the fundic mucosa did not vary with diet or time after feeding. It is suggested that the increased incidence of esophagogastric ulcers observed when fine corn is fed is mediated by increased acidity or increased pepsin activity or both in the relatively unprotected esophageal region of the stomach. These effects are probably brought about by more mixing of gastric contents as a result of a greater fluidity.