Rat Growth Assay for Vitamin B12

Abstract

The growth response of vit. B₁₂ depleted rats under the conditions studied is proportional to the vit. B₁₂ administered in the critical range of .025-.1 μg per rat day. Oral and injection administration of the vitamin at critical levels yield approximately equal growth responses. Addition of the vitamin to the diet, multiple dosing or single dosing the first day of assay also appear roughly equivalent. A preliminary correlation between the results of microbiological and rat assays as applied to injectable liver extracts was obtained.