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      The basic dietary requirements for a horse are divided into 6 major categories which we will deal with here.

1.      Water - it is the most overlooked nutrients. Average consumption is 43-65litres per day, and the horse requires this amount to maintain it's metabolic rate as an average 500kg mature horse's body contains between 325-375 litres of water - working horses or pregnant or lactating  mares will use and require up to 130litres per day. Long distance endurance horses should be allowed to drink where ever and whenever there is water available, and should be allowed as much as they want after they have cooled down to rehydrate.

2.      Bulk (roughage) - all horses require bulk in the form of roughage in the forms of hays (either legume, cereal or grass) to maintain gut fill and to obtain their supply of digestible energy in order to maintain metabolic rates. Remember, horses are designed as continual grazers of roughage, and eat small amount on a continual basis. If they don't get an adequate amount of bulk on a continual basis, their digestive system will not function properly, and the horse will not be able to function properly. The preferred method of providing this bulk to horses is in the form of 24 hr/day grazing, however in some instances this is not possible, and their feed requirement will need to be supplemented. It must be supplemented by -

      High quality roughage free of poisons or poisonous weeds or other plant matter, moulds or other contaminants.

      Feed the roughage or pasture at a minimum rate of 1.5% of the horse's bodyweight - for an idle horse. Working, pregnant or lactating mares and stallions in stud season have a greater requirement according to the level of work being performed.

      Light work (15-20minutes walking, jogging/trotting) the level will rise to 1.75%.

      Medium work, or stallions in stud season(30-40mins per day loping/cantering) have a requirement of 2% bodyweight, and

      Hard or intense workout (45-60+ mins/day loping/cantering, galloping, jumping etc.) require 3% bodyweight in roughage.


Roughly this requirement for an average mature horse of 500kg is-


Light wk/8.75kg;

 moderate wk/10kg; &

Intense work/15kg of roughage per day.


Also remember all horses have a different requirement and should be fed as individuals, but it vital to maintain good health that they get their roughage requirement, and feed daily at the rate they will be worked, not simply kept on one ration because it is easy. Somewhere along the line, you will find you'll turn the horse out for a spell for a couple of days, and if it is a high level eventing or performance horse and still on the same ration as when it is performing, then you will find behavioural problems start to rear their ugly little heads.


3.      Energy - the requirement for digestible energy in the horse is fairly easy to establish simply by looking at the horse. If it is fat or obese, then it will require less megajoules per day, if it is poor and thin, then the energy requirement will soar dramatically. Remember, it is easy to keep a horse in good condition once a weight level has been established.  If the horse has been in energy deficit for a prolonged period of time, then it will be a costly and long experience to bring it back up to the required condition for it to be able to perform or function at optimum levels.

In Australia we refer to the energy content in terms of Megajoules (Mj.) in the USA it is referred to as Megacalories (Mcal). If you need to convert Mcal. To Mj. Simply multiply the Mcals by 4.185 and this will give the same amount in Mj. The requirement for energy in the working, pregnant or lactating horse is also greater than for the idle horse.

The formula to work out the required amount of energy is - 1.4 + (0.03* BW)*4.185

An average idle 500kg horse will look like this - 1.4+(0.03*500)*4.185= 68.6Mj/day.

The requirement advances as the work load or intensity increases.


4.      Protein (amino acids) - Protein requirements for horses are as not as critical as feed manufacturers would have us believe, horses do have a requirement for good quality protein. Protein is made up of amino acids. A horse requires 22 amino acids. It synthesises all but 10 of these, and they are provided in good quality protein meals such as soybean meal, rice bran, etc. Protein IS however a major consideration for pregnant and lactating mares and young growing horses. Amino acids such as Lysine and Threonine are what is known as 'limiting amino acids', and without these products, the young growing horse will simply not develop into the horse you'd imagined due to stunted growth and the limbs and bones not developing properly. Protein is important in that it is the ingredient that repairs and maintains muscle mass that is either growing due to exercise, or has been damaged and need repair of replacement due to exercise etc. excess protein has also been associated with the syndrome known as 'tying up', as has the feeding of greater than average amounts of grains that contain high levels of starches.


5.      An average mature horse will have a protein requirement of about 8% of its feed, whereas the working horse and pregnant or lactating mare has a requirement of about 10%, and the growing horse (yearling) has about a 14% requirement. (these figures are on a dry matter kg. base, or 80grams/kg; 100grams/kg; and 140grams/kg).

It is also important NOT to overfeed young growing horses on protein or over feed DE as it can cause DOD's (developmental orthopaedic diseases) bent and angular limbs, osteochondrosis dissecans etc. not to mention founder etc.


6.      Minerals - mineral requirements are very complex and quite often misunderstood in their requirement or added to with 'natural' feeding regimes without the person knowing what or why they are feeding the particular minerals which seem to come to the surface whenever people get on websites and take advice from people who don't know what they are talking about. This is a dangerous practice and should be avoided as a balance between minerals is vital to a horses health, such as calcium:phosphorous ratio, VitaminE & selenium correlation Copper and zinc etc. once the balance becomes upset, so does the horse and can begin behaving in irrational or erratic ways along with the onset of ill health and diseases.

7.      The relationship between Ca. & P is critical, and the correct ratio is 1.1 : 1, and research trials up to 5:1 have been conducted with non-favourable results. It is also important if the horse is being fed largely on high quality prime lucerne or clover hays, to ensure extra phosphorous is added to the ration to balance the Ca:P ratio. Another trap people fall into is thinking that a large majority of natural grasses and pastures are Calcium 'deficient' - they are not. They contain as much and sometimes more calcium than legume feeds, however, they also contain an additional calcium oxylate, which attaches, or binds to the calcium and will not allow for its uptake in the digestive system. When this happens, we end up with things like NSH (nutritional secondary hyperparathyroidism) or 'bighead' in the horse. these people are also responsible for adding calcium to the ration without recognising the need to balance it with the Phosphorous, and too much calcium, as with too much P may give a similar result as 'bighead' in the form of P deficiencies. So as you can see, the balance of minerals is critical. Optimum performance can not be reached and is linked closely with the Ca. : P ratio.

This relationship also occurs with zinc and copper. But the acceptable ratios are wider with a greater than 2.4mg :1 mg but less than 5mg :1mg

White muscle disease has been linked with the inappropriate intakes of Selenium and Vitamin E as well.


8.      Vitamins- most healthy mature horses will over the course of a day either obtain through sunlight, feeds or synthesis, obtain most of their vitamin requirements. A lot of them are obtained in vitamin precursors in feed (eg. Vit A by eating pastures with high levels of carotene), but young growing horses, performance horses, or horses under more than normal stress factors (disease, travel, weaning, etc.)  may not be able to synthesise or obtain adequate levels, and should be supplemented accordingly.

Eg: performance horses will require greater levels of Vitamin E along with selenium to prevent the onset of 'tying up'. They also require higher levels of niacin, choline, and folic acid than do pleasure horses. also, rehabilitating horse may benefit from supplementation of Vit B complex, and vitamin A. if you however think your horse is in need of a micro mineral or a vitamin, then don't simply feed one without the other. Make sure you get hold of a supplement that contains a balance of both.


      The horse must have access to clean fresh water at all times. Exception being a hot horse, which should only be allowed small intakes over a period of time until it has a chance to cool itself down and then allowed to drink freely to rehydrate.

      During transportation over long distances, it is also important to stop and allow the horse to drink.

      Base you feeding program on good quality roughage (hays and pastures) and only feed grain when they are needed to maintain adequate levels of energy and/or protein.

      Feed as often as possible - 2 or 3 times daily if possible.

      Feed an absolute minimum of 1.5% of the horse's bodyweight in roughage on a daily basis.

      Do NOT feed more than 0.5% of the horses bodyweight in grain or concentrate daily.

      NEVER feed more grain or concentrate than roughage on a kg/kg of dry matter basis.

      When evaluating rations, do not use % (other than to evaluate per kg/bodyweight), but use grams or milligrams per kilo for digestible energy, protein etc.

      Don't overfeed or use excessive levels of protein to performance horses or growing horses - too many feed companies place a huge importance on protein % of the feed. A horse is not a protein digester, he maintains life through the use of digestion of energy feeds in the form of roughages - if they had a huge requirement for protein we'd feed them on steak and eggs! Protein is made up of amino acids that the horse utilises in the daily repair and maintenance of muscle structure, that is why it is important to use good quality protein such as soybean or rice pollard meals, to ensure the horse gets the 10 of 22 amino acids he can't synthesise himself.

      When mixing rations, keep evaluating the protein content of the grain mix with the protein levels contained in the roughage source you are using.

      Make sure the mineral and vitamin requirements are being met and are well balanced. This can be achieved through feeding a properly fortified mineral mix from the feed store rather than messing about with individual products - you will hardly get it right most of the time anyway.

      Provide salt as free choice all the time.

      If you are feeding high levels of prime lucerne, you will need to balance the calcium:phosphorous ratio - once again, mineral mix.

      Keep your horse in a good moderate body condition. Obesity brings on physical, digestive and behavioural disorders.


mail: horseproblems@horseproblems.com.au