Milk Like a Cow, Eat Like a Pig: Developments in Nitrogen Efficiency and Amino Acid Balancing for Dairy Cattle

Abstract

In the nitrogen nutrition realm of the dairy industry, dietary crude protein is the go-to indicator for the overall nitrogen content within a given ration. But fallacies exist and bias emerges when using crude protein as a proxy for nitrogen status. Because each amino acid has its own percentage nitrogen which makes it up, and the amino acid profile for a given feed or forage may be different from one another, the assimilation of every amino acid into a generalized crude protein can either over or under-predict the nitrogen in a given diet. A study conducted in our lab focused specifically on nitrogen efficiency. Four dietary treatments were formulated, varying in the degree of amino acid balancing and overall nitrogen content in the diets. Data from this trial, along with several others, has provided the information to begin calculating optimum amino acid ratios when regressed against the energy content of the diet, much like what is done in swine nutrition.