Protein – good guy or bad guy?
Summer brings its fair share of challenges. Laminitis, lumps and bumps on the skin, sunburn, fly worry and in some horses, even tying up will be worse. A cause is wanted for any problem, for when we have found the cause, we can set about fixing the problem. Mismanagement, excess feed, too much sugar and genetic predisposition are all to blame. What is often, erroneously, blamed, is protein. Your local expert is called in, looks at the bag of feed you are using in minute amounts because the grass is doing a good job of keeping weight on your horse, sees it is 18% protein, sucks his teeth and declares, “that’s your problem, too much protein!”
Protein is essential for every organ of the horse and not least for supporting, repairing and building muscles. It is also needed for hooves, bones and even coat. By law, the total protein, also called Crude Protein (C.P.) has to be declared on feed bags, but this figure is only part of the equation. Protein can be good or bad quality, and can be digestible or indigestible.
Good quality protein is protein in which the amino acids of which it is composed, are in the right balance for the horse’s body. Good quality protein is found in forages, such as grass and lucerne/alfalfa. The protein in grains (such as oats, barley and wheat) and pulses (peas and beans) is generally poorer quality, lacking sufficient amounts of one or more amino acids.
The digestibility of the protein reflects how much of the protein needs to be broken down by enzymes in the fore gut (stomach and small intestine). “Indigestible” protein passes through to the hindgut (large intestine) where it can be used by the gut flora. These micro-organisms are essential to the horse. They break down fibre and turn it into nutrients for the horse, but just like any living thing, they need nourishing and in particular, they need protein. So the indigestible protein in the horse’s diet is vital for them, keeping them healthy so they in turn can nourish the horse and also provide the horse with Vitamins B and K.
The protein in cereals and pulses is on the whole highly digestible, with up to 90% of it being digested in the fore gut and so with little left over for the gut flora. The protein of forages on the other hand, is only about 50% digestible. It does not impact adversely on the horse, but does feed the gut flora.
Before making a judgement on whether the horse has enough, or even too much, protein in the diet, it is essential to take account of everything that the horse eats and the type of food it all is. We rarely worry about grazing being too high in protein, and rightly so, but most pastures will go through the summer and even into the winter with levels of around 20% protein. Long grass that has gone to seed may drop and will be down to single figures, but grazing prevents this happening. Well-managed grass can be up to 26% protein.
It is far more pertinent to worry about sugar levels in grass. High sugar levels cause obesity, laminitis, ulcers, colic, behavioural problems, Equine Metabolic Syndrome (EMS), tying up and more. None of these conditions is triggered by high protein from forages. The highly digestible, but poorer quality, protein of cereals and pulses is accompanied by high levels of starch, making these feeds even less appropriate for very many horses.
Look at all the elements that your horse eats and only make a judgement when you have the total facts and not just a small bit. Horses have spent 50 million years perfecting the art of survival on forage and have done pretty well so far!