The Vitamin B_<12> contents (mμg/ml) in serum of Hereford, Japanese Shorthorn, and Japanese Black Cattle were 0.41〜0.46,0.40〜0.45 and 0.25〜0.31 respectively. Japanese Black Cattle showed a significantly low B_<12> content as compared with that of Hereford and Japanese Shorthorn, although the growth was normal under the conditions.
