Lysine, methionine and threonine are known as rate-limiting amino acids. They are required in the horse’s diet because they cannot be made in the body. Of the 21 amino acids that exist, these three are most commonly deficient in the horse’s diet.

Amino acids are the molecular building blocks of proteins. Proteins have many functions in the body; they form structural components of cells, act as hormones and act as enzymes that carry out metabolic processes.

Horses that have inadequate protein or amino acid intake might experience:

  • Poor hoof and coat quality
  • Persistent fatigue
  • Slow recovery from illness
  • Loss of muscle mass

When an essential amino acid is deficient to the point of limiting protein synthesis, it is called a “limiting” amino acid. Lysine, threonine, and methionine are typically considered the first, second, and third limiting amino acids in equine diets.

Cereal grains and grasses that make up much of the horse’s diet are naturally low in these three amino acids. Legumes such as alfalfa and soybeans are typically higher in protein and provide more lysine, threonine, and methionine.

Horses do not store excess amino acids in their body and they must be supplied regularly by the diet to avoid deficiency. Some horses may benefit from supplementation to ensure they obtain adequate amounts of protein.

Mad Barn’s Three Amigos is an essential amino acid blend providing lysine, threonine and methionine in a 5:3:2 ratio.

We also offer L-lysine, DL-methionine and threonine as single ingredients that can be top dressed based on each horse’s individual needs.