1 THE ROLE OF FEED AND FEED PROCESSING IN DEVELOPMENT OF GASTRIC ULCERS

Stomach lesions were proposed as a concern in commercial production of swine when Bullard (1951) documented esophagogastric ulcers as the cause of death in an adult boar. In the past 5 to 7 years, with the widespread use of European genotypes and modern grain processing techniques, stomach ulcers have emerged as a major health concern in the U. S. swine operations. Our experiences at Kansas State University indicate that for each 100 microns decrease in average particle size of corn in swine diets there is approximately a 1.3% increase in efficiency of gain. However, the incidence of keratinization and(or) ulceration also tend to increase in nursery pigs (Healy et al., 1994), growing-finishing pigs (Cabrera et al., 1994; Wondra et al., 1999b,c), and lactating sows (Wondra et al., 1995d,e) as particle size of the diet is reduced. Reimann et al. (1968), Maxwell et al. (1970, 1972), and Regina et al. (1999) reported that smaller particle sizes of cereal grain increased fluidity of stomach contents. Those authors hypothesized that the increased fluidity allowed more mixing of stomach contents; thus, pepsin and digestive acids were continuously in contact with the ulcer-prone mucosa of the esophageal region of the stomach. So, in the decisio