Alfalfa hay usually provides at least b half of the roughage used for California milk production by dairy cows during some portion, if not all, of the 365 days of the year. It may be the only source of nutrients for dairy cows on grade B dairies during the winter season. Selection of alfalfa hay is a major management consideration for California dairymen because the nutritive value and feeding quality are highly variable. An accurate gauge of the nutritive value of a given lot of hay is the level of crude fiber it possesses. A method for evaluating nutritive value from the crude fiber content has been developed by the California Experiment Station. Commercial laboratories, using this method, have been available to test samples of hay submitted by progressive dairymen.