08/21/2026
HORSES DON’T HAVE PROTEIN NEEDS — THEY HAVE AMINO ACID NEEDS (Part 1 of 2)
Protein itself isn’t really the goal. What your horse’s body actually needs are the individual amino acids that protein is made of.
🦄ESSENTIAL vs. NON-ESSENTIAL
Essential amino acids can’t be made by the horse’s body in sufficient amounts, so they must come from the diet, think lysine, methionine, threonine, and the branched-chain amino acids (leucine, isoleucine, valine). Non-essential amino acids can be synthesized internally, so as long as overall protein and nitrogen intake is adequate, deficiency is rarely a concern for these.
✨WHAT IS A “LIMITING” AMINO ACID?
Protein synthesis only works if every amino acid needed for that protein is present at the same time like ingredients in a recipe. If one essential amino acid runs short, the body can only build as much protein as that one amino acid allows, no matter how much of everything else is available. That amino acid is called “limiting.”
Lysine is the only amino acid with an actual documented requirement in horses (per the National Research Council’s Nutrient Requirements of Horses) and is considered the first-limiting amino acid, especially in grass- and cereal-based diets, which tend to run low in it. Threonine is generally considered the second-limiting amino acid, and methionine is often named as a candidate for third, though the data on methionine are mixed, with some studies showing benefits, some none, and some even negative effects.
💪WHY DO THESE AMINO ACIDS MATTER?
Amino acids are the building blocks for essentially every protein structure in the horse’s body including muscle, hoof horn, hair coat, connective tissue, enzymes, even hormones. When lysine, threonine, or methionine are chronically short, research and clinical observation link this to reduced growth rate in young horses, poor muscle development or topline, dull coat, and weaker hoof quality because the body simply can’t finish building those proteins without the missing piece.
For more information or to have your horses diet evaluated send me a message.