Inhaled feed particles in experimental pigs with and without vitamin A deficiency.

An attempt was made to experimentally reproduce an unusual respiratory disease of pigs fed a dusty mixture of finely ground peas, wheat, and barley. Groups of vitamin-A-deficient piglets from this herd were either given dry feed and daily exposure to dust from the feed or were given wet feed. Vitamin-A-fortified pigs of another stock were also given the dry feed and dust exposure. The upper and lower respiratory tracts, renal pelves, and interlobular ducts of salivary glands were studied histologically. The distinguishing features of lungs were starch particles from feed (up to 31.2 mum in diameter) in all lungs (but more in lungs of pigs given dry feed), free alveolar macrophages, giant cell formations, and mild degenerative processes of respiratory epithelium. The epithelium of most renal pelves was marked by mucinous degeneration.