ISSUE FOCUS FEED & ADDITIVE MAGAZINE February 2026 37 • Oversupply of some amino acids • Metabolic energy costs associated with excreting excess nitrogen due to oversupply • Lost production potential due to imbalanced AA supply The result? Inefficient nitrogen use, unnecessary feed costs, and suboptimal performance. Today, nutritionists increasingly recognize that the solution isn’t more protein—it’s the right balance of nitrogen sources. Switching to amino acid-focused ration formulation allows us to “narrow the road,” delivering only what the cow needs and reducing waste in the process. Commonly, this can result in decreased CP of around 2 percentage units. This creates a more efficient cow. Dairy cows require ten essential amino acids (EAA) but methionine and lysine consistently rise to the top as most limiting for milk and milk protein synthesis. Histidine often follows, depending on the diet and production system. Emphasis is often placed on lysine, methionine, and histidine for this reason; however, all EAA are required and must either be produced by microbial protein in the rumen or consumed by the cow. For that reason, it is vital to assess all EAA that are within the metabolizable protein portion, since this would encompass AA that bypass the rumen and AA contributed from microbial protein. Currently, only rumen protected methionine (RPM) and rumen protected lysine (RPL) are widely available in commercial forms, making them the primary amino acids that can be reliably supplemented in precision rations. Even with high quality protein ingredients, reaching ideal methionine and lysine through feedstuffs alone is difficult—making rumen protected products essential nutritional tools. Utilizing rumen-protected AA such as AminoShure™-XM (Balchem Corporation, Montvale, NJ; 38% metabolizable methionine) and AminoShure™-L (Balchem Corporation, Montvale, NJ; 24.3% metabolizable lysine) allows for a consistent and reliable source of metabolizable methionine and lysine. Additionally, using a range of protein ingredients improves the overall AA profile and reduces dependency on any single feed ingredient’s inherent variability. This strategy is more likely to provide a comprehensive supply of all EAA and meet the needs of the rumen. Rumen protected AA can then be used to “fine tune” the final balance. To test this concept, a study at Cornell University designed multiple rations with varying AA supply. Comparing a ration with adequate methionine but inadequate metabolizable protein to a ration Photo: Diane Kuhl | Shutterstock
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