Fisheries Research Report No. 1730, 1966

Michigan Department of Conservation
Research and Development Report No. 80
Institute for Fisheries Research Report No. 1730, 1966
Comparison of the Michigan 2B and Mc Nenny 13-4 Diets for Fingerling Brook Trout

Leonard N. Allison

      Introduction.-The dry, pelleted diets, which are now used in most trout hatcheries, are not completely satisfactory. The problem is to formulate a diet of dry ingredients which will contain all of the essential food elements present in fresh meat. In 1956, Dr. E. F. Grassl developed a “dry” diet which he designated as the Michigan 2B formula. Since then, studies made by various agencies in the United States have greatly increased the knowledge about diet requirements of trout, and new products have been developed.
      One of the newer diets that has given encouraging results with rainbow trout was developed by the U.S. Bureau of Sport Fisheries and Wildlife; it is known as the McNenny formula. This formula has been changed in recent years. The McNenny 13-3 preparation was followed, in 1964, by the McNenny 13-4 which included a greater quantity of certain vitamins as the major change. (The ingredients of the McNenny 13-4 and the Michigan 2B diets are given at the end of this report.) The McNenny 13-4 was replaced with a 13-5 formula in 1965, after the present test was completed.
      In July 1964, Mr. Max A. Hunt, Regional Fisheries Supervisor for Region II, suggested that a comparison of Michigan 2B and McNenny 13-4 diets be made on fingerling brook trout at the Grayling and Oden hatcheries. The principal objective of this study was to compare the vitality of fish on the two diets, as reflected by microhematocrit and hemoglobin values. Rates of food conversion and mortality also were considered.