抄録
The rumen contents were taken at regular intervals through a permanent fistula of goat under normal feeding, and fractionated into Infusoria, bacteria, and Infusoria-bacteria free fractions. The vitamin B_<12> activities of each fraction were measured by using Euglena as a test organism and the following results were obtained : The vitamin B_<12> activity of rumen contents was 77-115μg per 100g of dry matter 4-7 hours after feeding. It appears that the goat obtained 12-34μg of true vitamin B_<12> per day from the rumen in which the vitamin B_<12>-like substances, containing the vitamin B_<12>itself, were synthesized. The vitamin B_<12>activities of Infusoria and bacteria fractions became maximum 7-8 hours after feeding, and especially the change of the vitamin B_<12> activity of the bacteria fraction was remarkable. The vitamin B_<12> activity of Infusoria-bacteria free fraction was low, but this fraction had a tendency to increase its activity 7-8 hours after feeding.
