This requires the use of a hay probe. The probe should enter the bale from the butt end and cut a core a minimum of 12 inches long and 0.5 inches in diameter. A sample should consist of a minimum 15 to 20 cores, should be from the same field and cutting of hay, and should represent no more than 200 tons of hay. Laboratory analysis usually consists of moisture, protein, some measure of fiber, and an estimation of energy and digestibility. All feed analysis should be compared on an equal moisture basis.
Protein is important economically for total ration formulation.
The most common and dependable test for protein is a Kjeldahl nitrogen process. Nitrogen is in a relatively constant 6.25 to 1 ratio with total protein. Total nitrogen multiplied by 6.25 equals crude protein. Some very soluble nitrogen in early-cut alfalfa is not true protein. The bacterial protein is in turn utilized by the cow in a manner similar to that of dietary protein.