Qualitative Adequacy of a Chemically Defined Liquid Diet for Reproducing Germfree Mice

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Abstract
The objective of this study was to determine if germfree mice could be adequately nourished by a diet containing only known nutrients in chemically pure form. This study was made possible by the availability of chemically defined diets in liquid form which could be filter-sterilized without loss of chemical definition. Germfree mice required special modifications in the proportion of nutrients in order for them to adjust to the diet. Modifications were also made in the course of the experiment to improve nutritional adequacy. Mice fed this type of diet were able to reproduce into the fifth generation, demonstrating that the diet must contain at least minimal amounts of all essential nutrients. Quantitative insufficiencies or imbalance, however, were indicated by a high incidence of sudden death at 10 weeks of age, by loss of some females shortly before or after they had delivered litters, and by generally low breeding performance. Increased magnesium content of the diet reduced the incidence of sudden death. Second generation mice survived up to 21 months on the diet before loss by accidental contamination. It is concluded that the diet contains all essential nutrients but that the proportions of nutrients need to be altered for periods of heavy nutritional demand.