Diets containing skim milk powder as the source of protein and vitamins other than A, produce results different from comparable diets made up from whole milk powder. Growth is about normal or may be better than normal. Reproduction and rearing of young is not normal. There are few or no litters, and the young almost invariably die. The period of producing the first litters may be much delayed. Addition of yeast or wheat embryo has resulted in normal growth and in the normal rearing of the first litters of young. The second generation rats are growing normally and appear to be in fine condition due to these supplements