Protein – The Misunderstood Nutrient


Many people equate protein with energy, but it has many other important functions as well.

Horses require five main classes of nutrients to survive. These include water, carbohydrates, protein, vitamins and minerals. After water, it is the most important – and the most misunderstood. Protein provides the building blocks for bones, muscles, and virtually all the body’s soft tissues. It is essential for growth and repair.

Their Function

Long assumed to be an energy source, it actually has quite a different function – it provides amino acids. In fact, they are made up of a chain of amino acids. The types of amino acid, as well as the length of the protein chains, differentiate them. To be more concise, horses require amino acids rather than protein.

Understanding Amino Acids

There are 22 so called “primary amino acids”. Only ten are presumed necessary for the horse because his body doesn’t manufacture enough of them, but needs them in order to function.

Specific requirements of individual amino acids have not been established with the exception of lysine. Lysine is considered the “first limiting amino acid”. If there is not enough lysine in the diet, the horse’s system will have difficulty utilizing all the other amino acids.

Protein and Lysine Requirements

To help explain, here are a few examples of how to calculate protein and lysine requirements for horses. The following requirements were determined by the Nutritional Research Council in 2006.

Lysine requirements for maintenance of a 500kg horse (1,100lbs) Lysine (grams per day) = Crude protein requirement x 4.3%. The crude protein requirement set by NRC for maintenance horses is:

Minimum | Body weight x 1.08g = 540g of protein/day for a 500kg horse and 23.22g lysine/day

Average | BW x 1.26 g = 630g of protein/day for a 500kg horse and 27.09g lysine/day

Elevated | BW x 1.44 g = 720g of protein/day for a 500kg horse and 30.96g lysine/day

To demonstrate the highest protein demands in a class of horse, we will show NRC’s requirements for lactating mares of 500kg bodyweight in their first month of nursing: Nursing mare in first month of lactation: 500 x 3.07 = 1,535g of protein/day and 84.8g of lysine/day.

10 NECESSARY AMINO ACIDS
1. ARGININE
2. LYSINE
3. HISTIDINE
4. METHIONINE
5. ISOLEUCINE
6. LEUCINE
7. VALINE
8. PHENLYALININE
9. THREONINE
10. TRYPTOPHAN
NRC, 1998

Meeting Demands

Most protein demands are met with a good quality forage. Alfalfa cubes or a good quality 15% protein alfalfa hay, if fed at 1.5 % body weight, will give 1,000g. A 12 % alfalfa/timothy mixed cube or hay will yield approximately 800g. Analyze your hay, and balance it with a complete feed or a vitamin mineral balancer.


Great Lakes Agra Corporation is the leading producer and supplier of premium, high quality forage products and other emerging feed and food products for domestic and international consumption. greatlakesagra.com

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