Feeding Principles - how to work out how much feed your horse needs

Feeding principles.

You can bet your bottom dollar that there is going to be something difficult to understand, or confusing, when it comes to feeding horses and ponies. Unless of course you have a qualification in equine nutrition - which most of us haven’t.

Let me put in a caveat before we start. When you read through this article you may get the impression that you can calculate really accurately the requirements for your horse. The fact is, like us, individual horse’s requirements are different. Two horses, the same size in the same level of work may have slightly different requirements, so the calculations are a guide. Use your eyes and tools like a weigh tape to keep track of how your horse is getting on. Finally, bear in mind that the analysis of feeds is based on the average composition of its constituent parts, and they can vary quite significantly from the declared values. Add that to the big variations in forage quality and you can see why I have cautioned you to consider these principles with a degree of common sense.

There are a few basic principles that you can use to see if you are in the ball park. If you are having problems then I would suggest that you contact one of the many fantastic helplines run by the feed companies, or touch base with an independent nutritionist. [Contact details are easy to find online, alternatively you can contact us]. Assuming that you don't fall into that category, then the guidelines below should help. There are some difficult concepts to get your head around when it comes to intake, but first of all let's start at the beginning by trying to estimate how much your horse can eat and how much he needs for the work he is doing.

Most of us over estimate the amount of work our horses do and under estimate their body weight. Several companies now have weigh bridges which they use at yard clinics or events such as our ‘Good Doer Health Club'. These are fantastic when it comes to getting an accurate weight, but it isn't an everyday tool. So the good old weigh tape is great, especially if used regularly because you can at least see if your horse is gaining or losing weight. If your horse is too big for the weigh tape, you can use the following method for adult horses.


calculate a horse's weight

Weight in kgs =

(girth measurement in cm) x (girth measurement in cm) x (length measurement in cm) ÷ 1188

Now sight alone, surprisingly, is not very accurate, your horse could lose or gain as much as 40kg before you see the difference, so go for a more accurate method.

Let's start with workload. Be honest, take an average week, not the one where you are all enthusiastic and have had time to do loads of schooling or hacking; use the table below to see where you are.



Rough Description of what you would be doing


Quiet hacking, light schooling


Hacking out daily for 1-2 hours, 1/2 hour to an hour of schooling, riding club competitions


Intensive schooling sessions, regular showjumping, endurance, dressage competitions


Endurance riding (30+ miles) racing, 3 day eventing


Have you been honest? Good, make a note of the workload so you can use that information a bit later on. Now it's onto working out how much your horse can eat, if you have got a calculator handy now is the time to push the ‘on' button, if you are doing all this in your head then my advice is you should eat some chocolate to get plenty of energy into your ‘little grey cells'. Why do we need to know how much they can eat? There are 2 main reasons, firstly so you can get the right ratio between forage and hard feed, ensuring you don't feed too much hard feed and cause digestive problems. Secondly, if you can feed them close to their ‘appetite' they will almost certainly be happier; you know how you feel when you are on one of those low calorie, low intake type diets…

Right you have weighed your horse, not sure you have got it right? As a guide if your pony is 10hh then it is likely to be in the region of 200kg, if your horse is a 16hh ex racer type he is likely to be about 550kg and if it is a thumping 18hh shire it could be in the 900kg plus bracket and the likelihood is that the weigh tape didn't go round him anyway. This is where it can get a little confusing. Intake is generally between 1.5% and 2.5% of body weight. This generally depends on workload and age, so for example the harder they work, generally the more they will be able to eat. This figure is DRY MATTER. What? We will leave this thorny little issue for just a few minutes and come back to it later when we are looking at feeds. Let's get back to the question of calculation. Your 500kg horse in moderate work is likely to be around the 2% mark so, 500kg x 2% = 10kg per day. Not into percentages? Try this method, divide your horse's body weight by 100 and multiply the answer by 2, so our 500kg ex racehorse is 5 x 2 which un-surprisingly comes to 10kg.

You've got your horse's workload, you've got his intake [capacity], now you've got to work out his maintenance level. This is usually expressed in ‘mega-joules' which is the metric system for ‘calories'. This is the amount of energy he needs to do his daily thing of keeping alive and warm, wandering around the paddock looking for grass etc. If you divide his weight by 10 and add 18mj to that you will not be too far out, so our 500kg ex-racer will need 18mj + [500kg÷10] 50mj = 68mj of energy from his feed to keep him alive and well. Cold weather. It takes more energy to keep warm, so if it is cold his maintenance needs will increase by as much as 10 - 15%... more maths! On a cold day he may need 75mj to keep him happy. What if he doesn't get any more? He'll lose weight, slowly, but it will fall off. If you are trying to get your horse to gain or lose body weight, base your calculations on his desired weight rather than his actual weight.

This is great, we've got his workload, his intake and his maintenance requirement. We've even taken into account what to do if it gets cold. [incidentally, putting a thicker rug on when it's cold will save you feed as well as keeping your horse warm]. Now all we have to do is work out what extra feed he needs for work, how to balance forage to hard feed, how much crude protein he needs and finally the dreaded dry matter intake to understand and we've got it.

Let's start with workload. The most straightforward way of doing this is to add energy for every 50kg of your horse’s bodyweight. So if our 500kg ex racehorse is in light work we need to add 1 - 2 mj for each 50kg so dividing his weight of 500kg by 50kg gives us a nice easy 10 which you then multiply by 1 or 2 giving us 10 - 20mj. We add this to his maintenance of 68mj and we have got 78 - 88mj of DE per day. DE? he hasn't mentioned that before, well no, because this is where it gets even more confusing. Suffice it to say that there are a few ways of expressing the feed value of your horses daily diet, DE is the standard way and this is what is usually shown on the bag or technical specification of your feeds. If you feel a real desire to know more, then the internet is a great place to find out. Back to workload, if your horse is 3-day eventing, then you will need to add an about an extra 7mj for each 50kg of his weight so our ex racehorse will need an extra 70mj of energy - double his maintenance requirement [this doesn't mean double his feed]. All this extra energy has to fit into his dry matter intake [capacity] which means some careful calculations need to be done. Usually this extra energy for work has to come from hard feed, we need to be cautious here, why? Because your horse was designed to eat forage, they came from the plains eating poor quality grass. Your horse has a small stomach [about the size of a rugby ball in your 500kg ex racehorse] and a large hind gut full of micro flora and bacteria designed to break down poor quality grasses. Too much hard feed can cause your lovely horse lots of digestive problems. You may have come across the most common one in racehorses which is gastric ulcers, but it also impacts on his overall health, so don’t overdo it. He was built to utilize forage so that should be the major part of his diet, never below 50% and preferably 70% plus.

Now we can move onto balancing the forage to hard feed. This is all about ratios or percentages depending on how you want to deal with it. The other thing we have to remember is that this is based on the dreaded dry matter, which we will get to in a minute. Because your horse is designed to eat fibre [grass] it is important to keep his intake of this as high as possible whilst still meeting his energy requirement. If your horse is in light work you should be able to meet their requirements easily with about 75% [¾] forage and 25% [¼] hard feed. In medium work he is likely to move towards 60% [3/5] forage and 40% [2/5] hard feed. Just to confuse the situation a little, some hard feed can be forage based, so grass nuts or Lucie nuts [alfalfa nuts] will count as the forage portion despite them coming in cubes. If your horse is in hard work then the ratio is likely to be in the 50% forage and 50% hard feed. In an ideal world you should feed a minimum of 50% of your horses dry matter intake as forage. If you are going lower than this then take some advice, because at these levels of hard feed the potential for problems is pretty high.

That's taken care of balancing your horse's forage to hard feed so we can move on to protein. Protein has had a bad rap, being blamed for a variety of problems; trust me it's not all bad. It is essential for day to day life, especially if your horse is young, a breeding animal or in work, especially medium to hard work. Your horse will need somewhere between 7.5% and 8.5% crude protein in his diet up to moderate work. If you are working him hard then this will need to increase to between 9.5% and 10% of his diet. Breeding and youngstock will need a little more. I can hear you asking "how do I work this out?" Most feeds will have the crude protein on the bag, usually shown as CP%. This will normally relate to the dry matter - see it had to pop its head up again. We might as well deal with the dreaded dry matter intake now so that you can get to grips more easily with the protein thing. More math’s I'm afraid… The easiest way I find to work this out is to take the fresh weight and then multiply that by its dry matter. I'll give you a few examples:- Hay is about 85% dry matter or put another way it has 15% water in it. Most hard feeds are around the 87% - 90% dry matter range and haylage clocks in at around the 60% mark. If you are only feeding your horse one feed it is easy, let's say you aren't working him and he is on hay. Using your 500kg ex racehorse who is eating 2% of his body weight in dry matter, which we have already worked out equals 10kg and assuming he is fed to appetite and has 24 hour access. If the hay is 85% dry matter then 1kg fresh weight as it comes out of the bale is going to equal 0.85kg [or 850g if you prefer] so to eat 1 kg of dry matter your horse will have to eat 1.18kg of hay. [1kg divided by 0.85]. Let's get to some slightly bigger numbers so you can see what I mean. Grass, when it is standing in the field on a normal dry day is about 20% dry matter and 80% water. Your 500kg ex racer can eat 10kg of dry matter in a 24hour day. If grass is 20% dry matter [1/5] then it takes 5kg to equal 1kg of dry matter. Now multiply that by 10 and you have got a lot of grass, 50kg of the stuff to fill him up. Now if it was hay he would only need 11.76kg which is about 2/3 of a small bale. Got the dry matter thing?

Back to crude protein. This is a bit tedious when it comes to calculation, you will have to work out the total dry matter for each feed by multiplying the fresh weight by the dry matter percentage so let's take a simple one where your 500kg ex race horse is not getting any turnout and is fed hay plus a scoop of cool mix for his morning and evening feed. Let's also assume that 1 scoop weighs 1kg. You are feeding him 2 x 4.5kg feeds of hay in his Haybar, making a total of 9 kg. Now for the calculation, starting with the hay, if we assume it is reasonable quality and the crude protein [CP%] is 9% and the dry matter is 85% then I find it easiest to do the calculation as 9kg x .85 [85%, just stick the decimal point in front of the number, or even easier use your trusty calculator] which equals 7.65kg of dry matter. Then we have to find 9% of the 7.65kg of dry matter to get to the number of grams of protein, so 9% of 7.65kg equals 0.68kg or 680 grams. Now for the cool mix, our cool mix is 9%cp and is about 90% dm. Your ex race horse is getting a total of 2kg of mix x 90% dry matter is equal to 1.8kg [2 x .90] now you have to multiply the dry matter of 1.8kg by the crude protein percentage, which in our example is 9%. So our 1.8kg of mix is giving your horse .16kg of protein or 160 grams. Now if you can remember where we are, you add the 680g from the hay to the 160g from the mix you get 0.84kg or 840g of protein in the diet per day. If you have not lost the will to live by now, then you have only one more step to take and that is to divide the total protein of 0.84kg by the total dry matter of the 2 feeds which is 9.45kg which equals 8.8%. Now I didn't say this was going to be easy, you also have to read the labels carefully as sometimes the energy etc is declared as fresh weight. This obviously means that they are higher in energy or protein than a feed that has the same levels declared in the dry matter so you have to reverse the calculation to get it to a dry matter basis if you want to compare the two.

All this work doesn't take account of minerals and vitamins either! If your horse is in hard work, competing at a reasonable level or is not quite right then this does matter, so my advice would be to talk to one of the nutrition help lines to get the diet fine-tuned. If you are feeding the recommended levels of hard feed that the manufacturer has put on the bag for your horse, then you will be getting the minimum levels of minerals and vitamins for your horse, so unless you have a problem there is no need to worry. If you're not feeding this amount, and most of us don't, or you are on a forage only diet then the simple way to compensate is to add a min/vit supplement, or feed balancer. Oh and still on the subject of dry matter, quite a few companies quote the energy level especially, 'AS FED', which means that when you calculate it on a dry matter basis it will be higher than quoted.



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