Using Lysine in Cattle Feed

Cow : Lactating Cow Nutrition

Cow : Transition Cow Nutrition

Kevin Dill, Ph.D.

Senior Nutritionist – Dairy Technical Innovation

Lysine is one of the first two limiting amino acids in a lactating cow’s diet. When cows have adequate lysine in the diet, milk production, components and cow health are more fully supported.
However, lysine is lacking in almost all forage-based rations. Supplemental lysine supports cows to meet their potential. And certain lysine sources can do so in an efficient, cost-effective way.

Bioavailability and feed efficiencyUSA Lysine<sup>®</sup> offers a highly concentrated, rumen-protected lysine source with performance benefits.

Lysine must travel through the rumen and be absorbed in the small intestine to have an impact on milk production. Many lysine sources degrade in the rumen, losing their effectiveness. Choosing a rumen-protected lysine source that’s designed to withstand rumen degradation will ensure you get the most bang for your buck.  
Many products available are labeled as rumen-protected lysine, but they must be properly protected to help ensure maximum absorption in the small intestine to meet lysine requirements.
Bioavailability, or the percent of a substance that is absorbed, is also an important factor when choosing a lysine source. A higher lysine bioavailability means you can feed less and still meet cow needs for greater feed efficiency. Purina® USA Lysine® is an encapsulated, rumen-protected lysine source with 44% bioavailability to maximize its efficiency.

Lysine sources

Common sources of supplemental lysine include soybean meal, corn, blood meal and other high-protein commodities. There are also countless rumen-protected lysine sources available on the market. However, not all lysine sources are created equal.
Quality varies greatly in common commodity protein sources, which limits the amount of lysine available to the animal. Rumen-protected lysine sources, like USA Lysine®, provide higher, more consistent levels of lysine than other protein sources.
Rumen-protected lysine sources are also a cost-efficient option to provide a more concentrated amount of lysine. With commodity products, it’s challenging to provide the lysine needed without overfeeding other nutrients. And, if you’re overfeeding, feed costs increase, and nutrients are wasted.

Amino acid balancing

Lysine is not the only limiting amino acid to consider in the ration. Balancing both lysine and methionine, in addition to feeding proper levels of metabolizable protein (MP), provides the maximum impact on milk and component production.
Amino acid balancing in the ration includes three steps:
  • Step 1: Balance for and ensure adequate intake of MP
  • Step 2: Provide adequate levels of rumen-protected lysine
  • Step 3: Balance to the proper lysine:methionine ratio
Work with your nutritionist to ensure your ration is properly balanced for all limiting amino acids. A balanced ration will support more energy-corrected milk, fat-corrected milk and pounds of protein.
Learn more about USA Lysine®, fed as part of a Purina® MetaPro® balanced ration.