Corn is a common addition to equine diets, either on its own or as part of a compound feed. Corn is a relatively cheap, high energy grain and is also highly palatable. Seems like a good pick, right? It definitely isn’t, and I’ll talk about why in a moment.


First, it’s worth noting that you’re highly likely to find corn or maize listed as an ingredient in your compound feeds. There are a number of companies committed to making grain free feeds that are worth exploring as an option for ensuring that corn isn’t sneaking into your horse’s diet.

You’re probably wondering why I’m so averse to corn. Here are my top 4 reasons to keep corn out of your horse’s diet.

 1. Digestion – Horses haven’t evolved to consume grain. Period. Whilst they can digest a small amount of grain in the small intestine, if there is even slightly more than the small intestine can manage, undigested grain can end up making its way into the hindgut. The hindgut is specifically for digesting fibre and non-fibrous ingredients that end up in the hindgut will rapidly disrupt the balance of microbes and the functioning of the gut. In addition, the microbes in the hindgut will ferment the grain resulting in an increase of volatile fatty acids and lactic acid. This can in turn lead to major digestive upsets including colic and also increases the risk of laminitis.  Of course, processed corn is more digestible than whole corn but the same principle applies for all corn regardless of the processing it has gone through.

 2. Starch – Corn is very high in starch, which we know to be a leading factor in raised insulin; a central factor in the development of laminitis and EMS. It is important for many horses that the starch level in the diet remains low. Shockingly, the glycemic index for corn is 100 – the same as sugar!  If you’re trying to keep insulin levels in check and ensure that the starch content of your horse’s diet is low, check it for maize and corn in the ingredients list.

3. High in energy – The digestible energy of corn is very high. The average horse doesn’t require the level of energy provided by corn (if you’ve got a horse in race training, it might be worth considering – for everything else it’s over the top). So many horses today are branded as ‘bad’ as having a ‘poor attitude’ or being ‘naughty’. Often the culprit for behavioural problems can be found in the feed and excess energy being provided is a key element. We have a tendency to overestimate how hard our horses are actually being worked and therefore how much energy they need. Corn, with it’s high level of energy can be a source of behavioural problems that can be easily alleviated by eliminating corn from the diet.

 4. Mould and Mycotoxins – Corn is prone to spoiling and moulding. Mould that forms then releases mycotoxins, which can be harmful to equine health. It is unlikely that corn added to a compound feed will be contaminated with mould as they will have tested for that during manufacturing. However, in order to protect spoilage later on, mould inhibitors will often be added to feeds, which can be nasty chemicals in and of themselves, causing all kinds of gut disturbances. If you feed corn on its own, it’s important to monitor it regularly for any contamination or mould that might appear.

Those are the main 4 reasons I advise against feeding corn to horses, or compound feeds containing corn. If you're concerned about feeding GM products, you’ll also want to avoid corn as almost all of the corn grown in the US is genetically modified. Finally, many horse owners feed corn oil, which isn’t a good option for horses either. I have written about this in another blog post about corn oil, which you can read here.


How can you eliminate corn from your horse’s diet? Are you already feeding grain free? We’d love to hear about your experiences.


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