A horse needs muscle to run, so a big focus of training these athletes is developing the muscles that power them. But, just like you can’t build a brick wall unless you have the right type and number of bricks, a horse can’t build muscle unless you feed the right nutrients to build it.
So… what does a horse need to build muscle and where does it come from in their diet?
What is muscle made from?
Muscles are made from protein, and protein is made from tiny little building blocks called amino acids. There are 21 amino acids in a horse’s body, 12 of these the horse can make for itself. The remaining 9 must be present in a horse’s diet. These are known as the ‘essential amino acids’.
But not only must they be in the diet, they must also be present in the right quantities so a horse has enough of each of them to build muscle. If a horse runs out of any of these essential amino acids because there is not enough being fed in the diet, then muscle construction simply stops.
Because you can’t see this physically happening the concept may be a little hard to grasp, but imagine you were asked to build a tower out of coloured children’s building blocks with the repeating sequence blue-red-green-yellow… if you ran out of red blocks, construction stops because there is no longer the correct building blocks to continue with the right sequence of colours. Muscle building is exactly the same! If a horse runs out of one or more of these essential amino acids, then muscle building stops.
Not all proteins are the same!
Every horse feed, forage and grain you feed contains protein and we are all familiar with feeds being presented to us with a certain ‘% protein’. But it just depends on where the protein is coming from that determines how useful that protein is for building muscle.
Some protein sources have a very similar essential amino acid profile to muscle, so they are very useful when it comes to providing the right building blocks to build muscle protein and can be considered ‘good quality protein’. Other protein sources however contain either very low levels of some essential amino acids or the essential amino acids they do contain are not available for absorption and use by the horse. These are what we would call ‘poor quality proteins’.
This means the % protein value given by a feed manufacturer is almost useless in determining how well that feed will support muscle development, because if that protein is coming from a poor quality protein, it won’t contain enough essential amino acids in the right proportions and a lot of the amino acids it does contain will be useless to the horse.
But aren’t horse feeds made with good quality protein?
We know that horses need good quality protein in their diets so it should stand to reason that horse feed manufacturers would use good quality protein in the feeds they make. BUT, good quality protein is expensive. And because there is no requirement to guarantee anything other than % of total protein (often given as ‘crude protein’) on labels, cheap, poor quality sources of protein are often used in horse feeds to keep the cost of feed manufacture as low as possible. Which means a lot of feeds being sold simply do not have the right profile of amino acids to support proper muscle development.
Good versus poor quality protein
Two commonly used sources of protein in horse feeds are full fat soybean and cottonseed meal. These feed ingredients contain virtually the same amount of crude protein (36 – 37% crude protein), so when feeds are formulated just on the basis of crude protein content you could use the same quantity of either of these ingredients and it would give you the same amount of crude protein in the finished feed. But take note now of the price (Table 1)! Cottonseed meal is almost half the price of soybean, so if you were looking to manufacture a feed at the lowest cost (which is how many horse feeds are made), cottonseed meal would always be the ‘ingredient of choice’.
But, what you need to pay careful attention to is the lysine content of these ingredients. Lysine is the most important essential amino acid because it is like the red blocks in the example above … it is the first amino acid horses will run out of and therefore the one most likely to stop the muscle building process. Lysine ranges from 23 g/kg in soybean to just under 15 g/kg in cottonseed meal (Table 1). So even though cottonseed meal can give the same amount of ‘crude protein’ to a horse, it contributes far less in terms of essential amino acids, which means it is not very useful when it comes to building muscle.
Table 1: The crude protein and lysine content of soybean and cotton seed meal and their price per tonne as at March 2016.
It is also important to keep in mind that the amino acids in cottonseed meal have been shown in many published studies to be less available for digestion and absorption in multiple animal species when compared to soybean. This means some of the essential amino acids in cottonseed meal are ‘there’, but, they are completely useless to the horse because they are never absorbed into the body for use.
Finding a feed that will build muscle
The trick to figuring out which feeds contain good quality protein is in the ingredients list. Feeds that use the cheap, poor quality sources of protein will usually list ‘generic’ sounding ingredients like ‘vegetable protein meals’. If you want a feed with a consistent supply of high quality protein, look for feeds that have very specific ingredients lists (where they name each ingredient they use and there are no ‘generic’ ingredients) and one that preferably contains soybean as one of the sources of protein.
Protein quality really makes a difference!
I have seen a lot of horses over the years switch between low and high quality protein feeds and it still amazes me how much difference it makes to their muscle development, so much so that I almost feel like I am making it up when telling people about it. This concept makes perfect logical sense; you can’t build something unless you have exactly the right materials to build it! And it absolutely happens in practice.
So go and have a read of the ingredients list on the bags of feed you are using. If the ingredients sound generic, chances are all you are getting is a low quality protein meal. If they are, consider switching to a feed that uses specific sources of good quality protein, including high quality soybean, I would be surprised if you don’t see a difference in muscle development!
Dr Nerida Richards PhD
Equilize Horse Nutrition Pty Ltd
Here at Pryde’s EasiFeed we make all of our feeds using set recipes. Our feeds are never made on a ‘least cost’ basis, nor will you find cottonseed meal or any other low quality vegetable protein meals in them.
Instead, we use Australian grown, extruded soybeans as our primary source of premium protein in our racing feeds and we complement these with lupins and faba beans. Which means our feeds will provide your horses with what they need to build lots of powerful muscle.