A Look at First-Limiting Amino Acids

November 2015

Amino acids are needed for a cow to maintain her body function at peak levels, and we’re learning more and more about the value of amino acid balancing in dairy rations.

Much of the conversation around amino acid balancing has centered on first-limiting amino acids, which are the amino acids that are the first to become deficient in dairy cows.

Avoid deficiencies

An amino acid deficiency can inhibit the cow and keep her from performing and producing to her potential. The first two limiting amino acids are typically methionine and lysine, so amino acid balancing in rations often means ensuring the ration contains sufficient quantities of these two amino acids.

While rumen-protected products — both methionine and lysine — are available as supplements to help avoid amino acid deficiencies, evaluating your protein ingredients is another key to amino acid balancing. Different protein sources have different first-limiting amino acids and, as we’ll discuss in future posts, evaluating those first-limiting amino acids can help you formulate the best ration possible.