What impact does feed have on equine gastric ulcers?
When feeding, we distinguish between high-fibre base feed/ roughage, which covers the horse’s need for feed structure, and low-fibre concentrate feed, which provides the horse with energy. It is important that feed be balanced in order not to overtax stomach physiology and metabolism. We base our calculation of the correct ratio of basic feed and perhaps also concentrated feed on a "model horse" with a weight of 500 kilogrammes.
Our model horse is healthy and gets an average amount of activity – neither constantly in the stable, nor worked particularly hard. Under these conditions, a hay content of 2% of body mass, i.e. 10 kilogrammes per day, is recommended. Because gastric acid is produced continuously, part of the ration should constantly available during the night. Long intervals without feed will encourage excess acid formation in the horse's stomach.
If the horse eats too much concentrate feed, which passes quickly into the stomach, this can cause hyperacidity, as the horse will not have produced sufficient saliva to buffer the acid and additional acid will be produced through digesting the concentrate feed. To avoid this, it is important to feed the horse roughage first and then concentrate feed.
Another important factor when dealing with gastric ulcers: base feed and concentrate feed differ in structure and taste. Horses love to eat less-structured concentrate feeds, which they chew through less thoroughly and swallow more quickly than their base feed. This means that eating concentrate feed leads to the production of far less saliva (and less saliva in the stomach), and this will reduce its buffering effect.
In addition, concentrate feed absorbs acid in the stomach much less easily due to its smaller structure – and that’s bad news for the stomach’s mucous membranes. Consider, in contrast, high-fibre base feed, which requires much more thorough chewing. This in turn produces more saliva which adheres to the fibres and can then provide buffering effects in the stomach, whilst acid better penetrates the ingested base feed. This helps to protect the stomach.
There are other factors to consider: whilst high-fibre feed is a good and necessary thing, the plant parts should not be too hard and prickly, because these can cause lesions to the stomach wall and thus lead to stomach ulcers. Lucerne chaff has a structure that is unsuitable for horses with stomach issues, even though it requires more chewing and thus helps to produce sufficient saliva.
Care should also be taken if, for example, there are oak trees in or near the horse’s pasture: acorns contain tannins which, when eaten by the horse, can lead to gastric ulcers.
One should also examine the quality of the feed. Always select a high-quality feed, because impurities, mycotoxins or misfermentation of hay all can have negative impacts on the entire gastrointestinal tract. It should also be mentioned here that haylage and silage are unsuitable for horses susceptible to stomach problems, as the acids they contain can irritate the stomach lining.