The occurrence of feed-induced stomach ulcers in horses

Ponies were fed hay (n = 21) or mixed feed (n = 27; 128 g crude protein, 175 g crude fibre/kg dry matter) for at least 14 days (treatment against parasites with ivermectin before the experimental period). The feeding level was 18 g dry mater/kg body weight/day. After the feeding period (the experiments were conducted to investigate the water and electrolyte content of the alimentary tract in dependence on feed, feeding time and physical exercise) the ponies were slaughtered and the stomachs were visually controlled for the occurrence of ulcers. In the hay group no gastric ulcers were observed, but from the 27 ponies given mixed feed 10 (chi 2 = 7.71) animals showed ulcers on the cutaneous mucosa of the pars oesophagea localized along the margo plicatus. At 3.5 hours postprandial the percentage of dry matter in gastric contents of concentrate fed ponies was higher than in those which consumed hay; 12 hours after feeding the opposite took place. The gastric fill was rather similar, while the amount of chlorine and the pH-value respectively were 37 (+/- 16) mg/kg BW and 3.83 (+/- 0.83; n = 8) respectively in hay fed animals compared to 45 (+/- 17) mg/kg BW and 4.84 (+/- 0.55; n = 11) respectively in ponies, which consumed the mixed feed.