Feed Management of Good Doer Horses with Gastric Ulcers
Equine Gastric Ulcer Syndrome (EGUS) is most prevalent in horses working at high intensities fed low fibre, high starch rations, such as racehorses. However even leisure horses are not immune to gastric ulcers and on the Dengie Feedline we have regular enquiries regarding managing gastric ulcers in horses that manage their weight very easily. This in some ways can actually be more challenging to manage, especially if the horse also needs to lose weight!
Managing Gastric Ulcers in Horses: It’s All About Fibre
One of the key pieces of advice usually given to owners with a horse first diagnosed with gastric ulcers is to turn out 24/7 or feed ad-lib forage. The reason for this is that ad-lib access will allow the horse to eat little and often as nature intended. This encourages a longer chew time and therefore greater saliva production which is important as saliva contains bicarbonate. This is one of the few protection mechanisms the horse has in for the squamous mucosa where ulcers most frequently occur. Once chewed and swallowed, fibre also forms a saliva-covered, fibrous mat in the horse’s stomach. This helps to maintain a gradient of acidity in the stomach with more acidic conditions in the glandular region where acid is produced and an integral defence system exists, to a less acidic environment in the more sensitive squamous region.
The problem when it comes to feeding good doers and overweight horses is that 24/7 turnout on abundant grass or ad-lib forage could result in further weight gain which can bring its own problems -so what’s the alternative?
How Much to Feed Your Horse with Gastric Ulcers?
Fibre should be the basis of all horse’s diets. For horses that are good doers or that need to lose weight it is important to review the entire feeding regime. As a starting point remove any energy dense concentrated feeds such as mixes and cubes in favour of increasing the quantity of fibre fed. This will decrease the energy density of the diet, helping to manage weight, whilst maximising chew time as it takes significantly longer to chew fibre than it does mixes and cubes. To ensure the diet is balanced, top up with a feed balancer or broad-spectrum vitamin and mineral supplement.
The general advice for all horses and ponies is to feed no less than 1.5% dry matter of their bodyweight daily of fibrous feedstuffs and this includes dieting horses and ponies. For a 500kg horse this would be 7.5kg dry matter, or 8.8kg of hay as fed assuming the hay is 85% dry matter. This quantity is, however, less than the horse would consume if given free choice access and so should be split up into as many small, regular feeds as possible so that the horse is kept eating for as long as possible through the day and night.
A Link between Feeding Forage and Gastric Ulcers in Horses
A study in Denmark found that there was a significant link in the interval between feeding forage and the risk of gastric ulceration. Horses that had forage feeding intervals greater than 6 hours had 3.9 times the likelihood of gastric ulcers (Luthersson et al., 2009). In any feeding regime it is prudent to ensure that time without anything to eat is kept to a minimum. The largest proportion of forage needs to be left at times you won’t see your horse e.g. overnight. At this time methods should be employed to try and to slow the rate of eating to make the forage last longer. These could include putting the forage in separate locations within the stable to encourage more movement and foraging behaviour, and the use of small holed haynets.
Types of Fibre for Horses with Gastric Ulcers
When it comes to fibre and buffering potential not all fibre is the same. You may have heard that straw is ‘bad’ for ulcer horses so what’s the truth behind this and can you use it for good doers or overweight horses and ponies to aid their weight management as a lower calorie fibre source?
A study of horses in Denmark found that straw as the sole or predominant forage source resulted in a 4.5 times likelihood of gastric ulcers (Luthersson et al., 2009). The authors concluded that the potential reasons for this were that straw contains low calcium and protein levels, both of which are thought to aid buffering in the stomach, straw is highly lignified and if not thoroughly chewed may irritate the gastric mucosa if fed in large quantities and finally that straw as a fibre source may alter the fibrous mat in the stomach increasing the risk of acid exposure in the squamous mucosa.
In the UK straw is rarely fed as the sole forage source for horses. Recognising that straw as a lower calorie forage source can be useful to maintain an overall higher forage intake in good doers, current recommendations are to not completely avoid straw, but to limit intake to less than 0.25kg dry matter per 100kg of a horse’s bodyweight (Luthersson & Nadeau, 2013). For a 500kg horse this would be 1.25kg dry matter or 1.4kg as fed assuming 90% dry matter. Don’t forget that horses on a straw bed are very likely to tuck in if they are on restricted quantities of other forage!
Conversely you may have heard that alfalfa is a better buffer to acidity in the digestive tract. In contrast to straw, alfalfa contains higher levels of protein and calcium and it is this that is thought to offer buffering potential. An independent study at Texas A&M University showed that horses fed alfalfa compared to grass hay had a lower level of ulcer severity. In alfalfa-fed horses, 1 of 12 had ulcers whereas in horses on grass hay, 9 of 12 had ulcers. Horses that were initially fed alfalfa had a signiﬁcant worsening of ulcer severity scores when it was removed from their ration (Lybbert et al., 2007).
Although alfalfa as a fibre source is a naturally good buffer, for overweight horses and ponies or good doers pure alfalfa feeds should be fed in restricted quantities as it has a medium calorie level. Where it may be best to incorporate a pure alfalfa feed is prior to exercise where ½-1 scoop of pure alfalfa feeds can be given to encourage greater buffering. Otherwise products that incorporate alfalfa with other lower calorie fibre sources such as grasses or straw may be used as a larger part of the overall forage ration.
Feeding Oil or High Fat Feeds to Horses with Gastric Ulcers
The general reasoning behind feeding oil or high fat feeds to horses with gastric ulcers is that prostaglandins which inhibit acid secretion are derived from fatty acids. Oil may also bind free fatty acids within gastric fluid potentially creating a less acidic environment. Studies to date haven’t been very repeatable. Although one study found supplementing 45ml corn oil significantly lowered gastric acid output and increased prostaglandin concentration (Cargile et al., 2004), in practice another study where corn oil or rice bran oil were supplemented at higher levels didn’t find an improvement in the number and severity of ulcers compared to placebo horses (Frank et al., 2005).
Another often described potential benefit of the high fat feed supplement linseed is that it is very mucilaginous and could potentially form a protective layer in the stomach. One performance horse study looked at the effect of a linseed based feed additive on gastric ulcers in horses and found that it did not decrease the number or severity of gastric lesions compared to the control group (Hyyppa et al., 2010). Horses were fed an equivalent of 65g per kg of bodyweight of linseed per day which equates to 325g for a 500kg horse.
The main benefit of oil for horses with gastric ulcers is likely to be for performance horses where oil can be used to replace a significant proportion of starch in the ration as it is very energy dense. As oil is very energy dense it is not very appropriate to feed in large amounts to good doers or overweight horses and ponies. Even just 100g of oil will provide around 4MJ of digestible energy. Given average hay contains around 8MJ/kg digestible energy your horse could be munching on an extra 0.5kg of hay instead to increase chew time.
Top Tips for Feeding the Good Doer Horse with Gastric Ulcers
- Make fibre the foundation of the diet, both long stem and short chop, topping up with a supplement or balancer to provide a balanced ration
- Keep fibre intake as maximal as possible whilst managing bodyweight by using late cut hay and other lower calorie fibre sources
- Feed regular forage feeds split into as many small meals as possible when your horse is not at grass leaving a larger quantity overnight
- Feed a small alfalfa based meal prior to exercising
- Make sure your horse has constant access to water