Liquid protein supplements (LPS) are available commercially for feeding to dairy and beef cattle. They are easy to handle and mix with other ingredients, but liquid nutrients are usually more expensive than dry nutrients. Ingredients and nutrient content vary among products, but most are combinations of molasses, urea, phosphoric acid, and small amounts of other minerals and vitamins. The liquid protein supplement Pro-Lix also includes fish solubles, fermentation solubles, and brewers yeast. It contains 35 percent crude protein of which 17 percent is derived from nonprotein nitrogen.

The authors are grateful to Jeff Poston, manager of Jacques Dairy, Tulare, California, for the conduct of the trial with his herd; to Pro-Lix Companies, Aliceville, Alabama, for providing the liquid protein supplement; to Dairymen's Cooperative Creamery Association, Tulare, California, for modification of the feeding equipment used in the trial; and to Loren F. Bennett, Senior Programmer, Animal Science Extension, University of California, Davis, for statistical analyses