The influence of low versus high fibre haylage diets in combination with training or pasture rest on equine gastric ulceration syndrome (EGUS)

The aim of this field study was to examine the influence of a low fibre (LF) and a high fibre (HF) diet on the presence of gastric ulceration in thirty 3-year old Dutch Warmblood horses during training period and during pasture rest. In the first part of the study all horses were stabled individually and fed either an iso-energetic HF (75% haylage) or LF (25% haylage) diet for sixteen weeks. Horses were exercised daily throughout this period, after which the first gastroscopy was performed. The second gastroscopy for all horses was performed following a fourteen week Pasture period during which grass was supplemented with haylage. Contrary to expectations the scores for number and severity of gastric lesions during the Training period were significantly higher in the HF group compared to the LF group. Additionally, horses of the HF group showed high haylage retention in the stomach after 12 hours fasting, whilst the LF group exhibited marked bedding eating and coprophagia. The results of gastroscopy following the Pasture period with extra haylage feeding for all horses, were similar to the HF horses following the Training period. These unexpected results may be related to the retention of the pre-fermented feed (haylage) in the stomach leading to continuing fermentation with increased volatile fatty acid (VFA) production in the stomach. The consumption of bedding and coprophagy shown by the LF group may have limited the previously reported high risk of gastric ulceration on a lowfibre diet