Oat supplementation alters biochemical and physicochemical properties of gastric digesta – a possible contribution of feeding to gastric diseases in horses

Abstract Equine squamous and glandular gastric disease is highly prevalent and a concern for animal welfare. Biochemical and physicochemical properties of the feed are reflected in those of the digesta, and feeding-related changes in these parameters could play a role in the development of gastric mucosal lesions. A number of 24 horses were adapted to one of the following rations: pasture 24 h/day, hay ad libitum , hay ad libitum plus oats at 1 g starch/kg body weight/meal, and hay ad libitum plus oats at 2 g starch/kg body weight/meal. Samples of gastric digesta were taken post mortem. The addition of oats increased the intra-gastric pH and decreased water binding capacity, reflecting adsorption of gastric fluids to feed particles in the digesta. Oat supplementation also led to increased mucus concentration, suggesting an adaptive response to acid exposure. Feeding concentrates such as oats seemed to limit the natural sponge effect of the digesta, whereupon gastric acids largely remain on the mucosal surface. Although not demonstrated directly in this study, these results plausibly suggest that this mechanism could be causative for or support lesions of the squamous and the glandular mucosa.