Adequacy of chemically defined, water-soluble diet for germfree BALB/c mice through successive generations and litters

To determine dietary adequacy, germfree BALB/cAnN mice were fed ad libitum an ultrafiltered solution of chemically defined, water-soluble, low-molecular-weight nutrients. They received a measured daily supplement of membrane-filtered, distillation-purified soy oil containing vitamins A, D, E and K. Mice were kept on ash-free filter paper bedding, which they freely consumed. On this regimen, germfree BALB/c mice reproduced through nine generations, and through eight litters in one generation. Average number born per litter was 4.1, compared with 5.1 in control BALB/c mice, which had a conventional microflora and were fed a natural ingredient diet. From 21 to 32 d of age, the experimental mice gained more slowly than controls. After 32 d, experimental mice gained more rapidly than controls; their weights tended to be lower than controls at 45 d and equal to controls at 56 d. Intake-limiting effects of the diet appeared responsible for reduced growth rates and litter size. Experimental females showed a low incidence of deaths from cecal volvulus. Experimental males experienced a high incidence of deaths from colonic impaction of cecally-formed trichobezoars; this site of formation appeared to be unique to BALB/c males on the experimental regimen. These losses were judged to be unrelated to nutritional deficiency. No overt signs of nutritional deficiency developed in female mice which were fed CD diet up to 18 mo of age.