NUTRITION By Baileys Horse Feeds
WHO’S AFRAID OF
STARCH? l in the cooking! It’s al
S
tarch gets a lot of negative publicity these days and, whilst some may be deserved, it is often the way it is fed which is at fault. Horses are designed to function on fibre and, in their natural environment, where their basic aim is survival, it’s sufficient to keep them going. But having domesticated them and imposed on them the rigours of training and competition, we now find that fibre is not generally enough to provide the fuel they need to perform. We’d also find it hard to deal with the dramatic fluctuations in condition that feral horses and ponies go through in the wild, so alternative energy
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sources, such as cereals, have traditionally been the answer. That said, there are still plenty of horses and ponies, particularly those of native type, whose systems have adapted to deal with a sparse diet and as such now do almost too well on the modern pasture we now keep them. Starch is made up of chains of glucose molecules and is tightly packed in granules into cereal grains. It is there to provide food for the growing seedling, should the grain (seed) germinate and grow into a new plant rather than being fed to our horse. It provides a much more concentrated source of energy than fibre so the horse only has to eat a relatively small amount to gain the energy he needs. Much of its bad reputation has been gained though, through feeding excess quantities of grain. This can lead to over excitability, as the horse receives
too much energy, or to digestive or metabolic disorders, such as stomach ulcers, colic, laminitis or tying up, as the horse’s digestive system struggles to cope with the starch levels. The important thing with starch is that it must be digested in the stomach and small intestine and should not be allowed to pass on to the hind gut. The horse’s stomach is relatively small and not very stretchy so this limits the size of the meals we can give – too large and some undigested starch could flow out and reach the hindgut where it can upset the microbial balance. Hindgut bacteria are sensitive to any change in their environment and do not survive exposure to starch. So, if undigested starch reaches areas of the horse’s gut that it shouldn’t, not only will it disrupt the bacterial populations, so reducing the efficiency of fibre digestion, but toxins produced by the bacteria as they die can lead to diseases, such as laminitis. Humans find starch easier to digest if it has been cooked – we don’t eat
raw potatoes and always cook pasta and rice before we eat them. As research into equine nutrition and feed technology has progressed, we’ve found that cooking vastly improves the digestibility of starch for horses too, helping more starch to be absorbed in the small intestine. The most efficient cooking method has been shown to be micronisation using infra-red energy. Firstly, the grain is soaked to increase the moisture content and swell the starch granules. The grain is then passed under the infra-red heat source and, as water vapour pressure in the grains rises, starch granules swell and fracture – a process known as ‘gelatinisation’. The grain is then rolled to stop the gelatinised starch from binding to the protein in the grain, which would render it indigestible. To achieve maximum gelatinisation of the starch, and thus maximum digestibility, the temperature and length of time for which the grain is exposed to the heat are crucial. An inclusion of well-cooked cereal grains, in a properly balanced mix or cube, can therefore be an ideal source of additional calories for many horses, as long as rations are divided into as many small meals per day, as possible, and the horse also consumes sufficient forage. Many modern feeds contain a blend of energy sources, including cereals, a range of fibre sources and oils, which reduces the reliance on cereals. Indeed, there are now several which contain no whole
