Proteins are in the class of essential nutrients for horses, and they are comprised of both essential and nonessential amino acids. The quality of any given protein source is determined by the amount and balance of the 10 essential amino acids.
Protein is essential for life, health, and growth. It is utilized to support lean mass; muscle, bone, joint, tendon, organ, hormone, enzyme, hoof, and connective tissue health. Proteins aid in maintaining the structural tissues of the body and are also involved in metabolic stability by contributing to balance in the body's many enzymatic and hormonal functions.
Typically horses get their protein mainly from forage, but to a lesser extent, grain. Most grass hays run about 6-10% protein. Legume hays, such as alfalfa, can run as high as 12-14%.
Protein requirements can vary significantly depending on activity level, age, stress and workload. For a maintenance horse with no particular special-need, protein intakes of 7-10% are more than adequate. Excessive protein intake in a horse with no increased need can be stored as fat and increase the amount of stress the metabolism has to manage in its processing. This, in turn, can contribute to health issues in areas of genetic weakness. For that reason, hair mineral analysis and/or hay tests are suggested to examine each individual horse's needs.
If the need for a protein supplement is assessed, whey proteins are at the top of the list because of their protein quality. Very high levels and well-balanced essential amino acids occur naturally in whey protein. The branched-chain amino acids leucine, isoleucine, and valine support muscular integrity and contribute to blood sugar control. Lysine supports immune function and is the most important amino acid in horses. Glutamine protects lean muscle mass, including connective tissue, and supports brain and nervous system health.
Other components of good quality whey protein support gut health and integrity, which is vital to balancing immune function and inflammation.
There are a number of biological situations that increase the protein requirement to achieve and maintain optimal health: