Feeding Horses – an Art or a Science?

Feeding Horses – an Art or a Science?

There’s one subject guaranteed to cause confusion amongst horse owners and that’s feeding. With so many commercial feeds available its not surprising, as they all claim to be the best for your horse! So where do you start when devising a diet?

Horses are non-ruminant herbivores and their digestive system is designed to receive food on a little and often basis- they have a relatively small stomach, food moves through the small intestine quite rapidly and there is a large hindgut for continual microbial fermentation of fibre. Naturally the horse would graze for approximately 18 hours a day, taking small mouthfuls then moving on but domestic feeding practices can be quite different to this and alien to the horses anatomy and physiology. For example, the horse is designed to eat with the head lowered and feeding from mangers and haynets hollows the back and increases the risk of dental hooks. The need to chew is a natural requirement of the horse and if this behaviour is reduced due to limited forage provision it can easily lead to stress and the performance of unwanted behaviours such as crib biting and chewing wood. It takes approximately 10 minutes for a horse to eat a kg of bucket feed, compared to 40 minutes for a kg of hay. Because the horses stomach is relatively inelastic with a small capacity, it is designed to receive a small amount of food on a regular basis. Feeding large bucket feeds increases the rate at which food passes through, which can cause colic as food is only partially digested. Furthermore, long periods without food  in the stomach (such as at night for stabled horses) leaves the stomach lining vulnerable to attack from acid, which is continually produced regardless of the presence of food. This results in ulceration, which is extremely common in both leisure and competition horses and produces symptoms such as irritability, ill thrift, poor performance and crib biting.

picking a feed because you like the advert isn’t ideal

So for psychological and physical reasons, the predominant part of the horses diet should be a trickle feeding of fibre, which can be provided from a variety of sources such as grass, hay and haylage. If any of these are scarce or poor quality then additional fibre can be fed in the form of chaff, unmollassed sugar beet or fibre nuts. Any short fall in energy (calories), protein or vitamins and minerals can then be provided by supplementary bucket feed.  The requirements for these will all vary depending on the individual horse- its age, workload, health, breed, weight, etc. Any changes to feed, including hay and grass, should be done over a period of a couple of weeks to allow time for the digestive system to adjust otherwise there is an increased risk of colic.

The choice of supplementary feed should primarily be made on nutritional need, what works for one horse may not suit another and picking a feed because you like the advert isn’t ideal, not least because you pay a premium for heavily marketed products. The cost of all those adverts has to be paid for somehow! It is usually the energy requirement of the horse that is the main consideration. Energy of a feed is expressed in mega joules per kg (mj/kg), with 8 mj/kg being a low energy product and 13 mj/kg being a high energy product. To lose weight the horse needs to be fed less energy than it needs for day to day living and to gain weight it needs to be fed more energy. Every food stuff has an energy value, it is finding the right amount for the individual horse that is the key and this will fluctuate as the horses needs change due to things such as workload and the weather. How much energy is provided by the grass and hay shouldn’t be forgotten about either, for example some grazing and hay is actually unsuitable for a lot of horses as it is predominantly rye grass. This is grown for maximum milk and meat yield in livestock- things that aren’t relevant to the majority of horses; it may be highly palatable but you don’t need rocket fuel to power a moped!

Another important consideration when choosing your feed is starch levels, which should be kept as low as possible to minimise digestive disturbances. Some course mixes are 40-50% starch, which is unnecessarily high and even some feeds marketed as ‘calm’ or ‘non-heating’ can be 20% starch. Few horses need this level of starch in their diets as their energy requirements can be met without it; the many problems caused by a high starch diet include azoturia, laminitis, colic, obesity and erratic behaviour.

the predominant part of horses diet should be trickle feeding of fibre

Many leisure horses can get by on just grass and hay, supplemented with a small fibre based bucket feed with a vitamin and mineral supplement. Horses working hard, poor do-ers or veterans may need a bit more. This is where horsemanship comes in- using science to tell us about feeding principles, the digestive process and nutrient requirements and the art is applying this to the individual horse.

Natalie Bucklar
BSc (Hons), MSc (Equine Science)

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