Protein is often the most targeted nutrient when choosing a feed. After all, it helps to fuel the horse, giving the cells building blocks for growth, function, and repair. When we try to make sense of the nutrient by choosing a feed though, we can easily be overwhelmed with information and options. To simplify the jumble of numbers, percentages, and labels, we can talk about a couple factors to ensure that the horse is eating enough protein.
This is the golden question really; we see so many protein supplements on the shelves and look at feeds marketed to “fuel” or “power” our horses. If we look at the feed tag on a concentrate formula, it will often list between 10 and 14% protein. So when do we have enough?
If your interested in a complete nutritional overview, I highly recommend the National Research Council’s “Nutrient Requirements for Horses”. It clearly breaks down a horse’s nutritional needs, overviews ingredients, and offers easy to understand charts for nutrient requirements. Concerning protein, adult working horses should receive between 850 and 1300 grams of crude protein per day.
Bringing those numbers to reality— a 16 hand horse in work could meet his crude protein requirement with about 14 lbs (as fed) of mid-maturity alfalfa mix hay. While this much alfalfa provides a great source of protein, it would be an expensive diet in this part of the US, and too high in energy (Mega-calories) for the average horse.
Ergo, we supplement with concentrate. 1000 grams of protein can also be found in 20 lbs of a 12% crude protein concentrate formula. HOLD UP, that means 20 lbs of grain everyday. This is why good quality hay is so important to meet our horses’ protein requirement. To meet the needs of a 1200 lb horse in work, the combination of good quality hay and a well balanced concentrate formula will usually do the trick!
The crude protein value is a measurement of the overall protein content in a feed stuff. This value does not measure quality, but our horse’s digestive tracts certainly do! Think of quality as the test that the horse puts protein to. The test has two questions.
Can the horse’s digestive enzymes break down the feedstuff?
For a horse to have access to the amino acids provided in a feedstuff, the nutrients must be bio-available in the stomach & small intestine. These sites are where biological enzymes actively support protein digestion. If the feedstuff cannot be broken down via enzymatic digestion, it moves to the large intestine, where microbes break down the protein. While this is not necessarily harmful to the horse, microbes will not release the amino acids to the blood stream, but instead they will use the protein for their own nutrition.
Good quality protein is digested in the fore-gut
What is in the amino acid profile that makes up the protein?
Now that protein has been broken down to amino acids and absorbed in the blood, it needs to reach the cells to be restructured into biological protein. If the protein that the horse digests is not comprised of amino acids that the horse needs, the amino acids cannot restructure to biological proteins. For instance, if a feed stuff is 12% crude protein but lacks in lysine, lysine will be the limiting factor that prevents efficient use of all the other available amino acids. For this reason, we want to see good quality protein sources from legumes and feeds supplemented with amino acids such as lysine, methionine, and threonine.