Published online by Cambridge University Press: 09 March 2007
1. Vitamin B12 nutrition was studied in normal, coprophagy-prevented and antibiotic-treated rats on Vitamin B12-deficient diets with and without a vitamin B12 supplement; the indices used were excretion of total urinary ether-soluble acid (TUESA) and methylmalonic acid, and vitamin B12 assays on the liver and intestinal tract.
2. A significant positive correlation (r = 0.61) was found between TUESA excretion and weight of rats, and a significant negative correlation (r = −0.89) between TUESA excretion and liver vitamin B12 contents.
3. Although prevention of coprophagy reduced the contents of vitamin B12 in the stomach and small intestine, no effect on vitamin B12 nutrition, as assessed by TUESA excretion and liver vitamin B12 contents, was found. Rats in which coprophagy was permitted became vitamin B12-deficient, when given a diet in which vitamin B12 was low.
4. The amounts of TUESA and methylmalonic acid excreted indicated that streptomycin and erythromycin administered orally prevented vitamin B12 deficiency in rats on a diet deficient in vitamin B12. Liver vitamin B12 contents were, however, very low in these rats. this anomaly was thought to be due to the non-specificity of the Euglena gracilis assay for vitamin B12.
5. It was concluded that, under the conditions of these experiments, coprophagy was not necessary to the vitamin B12-sparing action of antibiotics.