ISSUE FOCUS FEED & ADDITIVE MAGAZINE January 2026 51 WHAT IS THE “IDEAL” PROTEIN FOR DAIRY COWS? To help farmers visualize amino acid balancing, Danish researchers explored the concept of an “ideal” protein for dairy.3 An ideal protein may be from a single source, or it can be formed from mixtures of protein ingredients that collectively meet the ideal amino acid requirements, while minimizing excess that must be disposed of through the liver and kidneys. The researchers presented an example where they calculated amino acid needs for a cow producing 66 pounds of milk and evaluated how well different feed ingredients – barley, corn, soybean meal, canola meal and fishmeal – filled the gap left after microbial contribution (Table 1). Using estimates for how much each amino acid would be available from rumen microbes, they calculated the deficit by subtracting the microbial supply from the total needs and then determined how much protein from each of the ingredients would be needed to fulfill the deficit. For each ingredient, the protein inclusion rate stopped when the limiting amino acid was met. To demonstrate the excess, the deficit was subtracted from the amount of the ingredient provided after the first limiting amino acid was met. The values are zero for the limiting amino acid. The total overage is the amount that must be processed by the cow. This research demonstrates that some proteins are better aligned with the cow’s amino acid requirements. For this example, canola meal stands out as a highly efficient source. This example found that canola meal and fishmeal were the proteins that best meet the needs of the cow. Corn protein is a poor source of amino acids when it comes to meeting the needs of cows for milk production. The amino acids from barley and soybean meal are intermediate sources. PRECISE FEEDING PAYS OFF While meeting the amino acid needs of cows is essential for milk production, doing so conservatively is more important as it’s the cow’s energy use that determines how she performs. By meeting the amino acid needs of cows and avoiding overage, less energy is wasted. However, these energy losses may not be considered by ration formulation programs and consequently, an opportunity for greater milk production and improved feed efficiency can be lost. When formulating rations, it’s important to go beyond just meeting crude protein levels. Targeting the right amino acid profile helps you reduce energy waste and optimize protein utilization and milk production. By focusing on the quality of protein sources, particularly those like canola meal that deliver amino acids more efficiently, you can improve milk yield, reduce energy waste and support long-term performance. References: 1Jennings, J.S., Meyer, B.E., Guiroy, P.J. and Cole, N.A., 2018. Energy costs of feeding excess protein from corn-based by-products to finishing cattle. Journal of Animal Science, 96(2), pp.653-669. 2Reed, K.F., Bonfá, H.C., Dijkstra, J., Casper, D.P. and Kebreab, E., 2017. Estimating the energetic cost of feeding excess dietary nitrogen to dairy cows. Journal of Dairy Science, 100(9), pp.7116-7126. 3Boisen, S., Hvelplund, T. and Weisbjerg, M.R., 2000. Ideal amino acid profiles as a basis for feed protein evaluation. Livestock Production Science, 64(2-3), pp.239-251. About Dr. Essi Evans Dr. Essi Evans is an experienced nutritionist with a long history of working in the animal research field. As president of E+E Technical Advisory Services, she assists and advises her clients through technical and managerial support to overcome research and development challenges. Evans’s work focuses on mathematical modeling, research trial design, technical support and product development.
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