I’ve noticed a few posts starting to circulate, extolling the virtues of SWEET POTATOES (Ipomoea batatas) for horses and ponies, especially for those with or prone to gastric ulcers.
Sweet potatoes fed in small amounts, either raw or cooked do not appear to present any health risk to the majority of horses or ponies and many owners feed them as a snack. Sweet potatoes are a good source of beta-carotene which is an orange coloured pigment belonging to a group known as carotenoids. Beta-carotene is a precursor of Vitamin A. As far as published research in horses, there are no studies that I can find on sweet potatoes in horses or ponies. One paper mentions a case of respiratory distress in a horse due to mycotoxin contamination of damaged sweet potatoes – but mycotoxins occur on many equine feed materials.
With respect to gastric ulcers, the link behind recommendations for feeding sweet potatoes may come mainly from studies of experimentally induced gastric ulcers in rats where it has been shown that beta-carotene may offer protection or promote healing. However, these cannot be directly transposed to horses as this is in a different species, the gastric ulcers are experimentally induced, the beat-carotene is given as a high purified dose (not through feeding sweet potatoes) and the nature of gastric ulcers in rats are similar to humans but very different to squamous, glandular and pyloric ulcers that occur in horses.
Sweet potatoes do appear in the EU Feed Materials Register. That means that manufacturers could include them in products such as feeds or supplements. They can be fed raw or cooked. However, cooking increases the starch digestibility, and starch can be high in sweet potatoes. Even when raw the starch in sweet potatoes is highly digestible. Whilst a large number of nutrition sources give the sugar content of sweet potatoes as being typically around 4-9%, the starch content is reported to be as low as 10% but as high as 69% in one source, with the average being 13-16%. A medium sized sweet potato will weigh around 130g or 5oz. Feeding half of one a day (65g/2.5oz), or perhaps 4-5 one inch cubes, would equate to around ~5g sugar and ~10g starch. Therefore, feeding more than this per day to a horse with EMS/Cushings or on weight management is not recommended.
If you do want to give sweet potatoes as a treat, then they can be fed raw or cooked. As always, any new feedstuff should be introduced slowly. They appear to be well tolerated by most horses and ponies, although there is limited, if any published research on their suitability. They are highly unlikely to have any impact on gastric ulcers and in fact, part of the normal management of equine gastric ulcer syndrome is to avoid feeds high in sugar/starch. Carrots are also a good source of beta-carotene and a better option as a treat than sweet potatoes due to their being lower in sugar and starch.