What does a good measurement of crude protein involve?

A good measurement of crude protein is based on the measurement of nitrogen content in the feedstuff. This is because protein is composed of amino acids, which contain nitrogen. By determining the nitrogen content of a sample, one can estimate the protein content using a standard conversion factor. This approach is practical and widely used in agricultural science since it allows for a relatively simple and rapid analysis of protein levels in various feed sources.

The other options—percentage of amino acids, measurement of carbohydrates, and measurement of fat content—do not directly provide a good estimation of crude protein. The percentage of amino acids represents specific building blocks of proteins but does not account for all proteins present. Measurement of carbohydrates and fat content, while important in evaluating overall feed nutrition, focus on different macronutrients and do not contribute to the assessment of protein levels. Hence, the measurement of nitrogen is the most reliable method for gauging crude protein in a given sample.