Several different forms of carbohydrates form what we call ‘fibre’. These carbohydrates include cellulose, hemicelluloses and lignin. Fibre cannot be digested in a horse’s small intestine. Instead, they rely on the billions of bacteria that live in their hindgut to digest it via fermentation for them. Fibre, which is also called ‘structural carbohydrate’, is essentially provided by the pasture, hay, chaff, haylage and high fibre feeds like sugarbeet and legume hulls in your horse’s diet. Fibre is the single most important component of a horse’s diet (after water) as without it, their digestive tract can’t function as it should. So why is it so important and what will happen if your horse doesn’t get enough?

With much focus at present on magnesium in equine diets the question of which form of magnesium is best arises. There are many ‘forms’ of magnesium available and suitable to be fed as magnesium supplements. Unfortunately, there are currently no extensive studies that look at the comparative bioavailability of these various forms of magnesium in horses. In fact, there are very few studies in any monogastric animal species, including humans, on the bioavailability of different types of this nutrient. To help us understand which forms of magnesium are best for horses, let’s first look at where and how magnesium is absorbed.