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The Effect of Cobalt on the Synthesis of Vitamin B¹² in the Rumen of Sheep¹

University of Wisconsin^,3

Abstract

An assay is described using chicks as the assay animal for determining the relative amounts of vitamin B₁₂ in the rumen of cobalt-deficient and cobalt-supplemented sheep.

In 4 chick assays an average difference of 42 gm. growth in 4 weeks was obtained between the rumen ingesta from the cobalt-deficient and the cobalt-supplemented sheep. The rumen ingesta from the cobalt-supplemented sheep gave the larger growth. One assay of the feces from cobalt-supplemented sheep gave 54 gm. more chick growth than did the feces from the cobalt-deficient sheep. The rumen ingesta from the cobalt-supplemented sheep under conditions of this assay contained approximately 60 y of vitamin B₁₂ per 100 gm. of dried rumen ingesta.

These data show that vitamin B₁₂ production was limited in the rumen of the cobalt-deficient sheep when compared to the production of the vitamin in the rumen of the cobalt-fed sheep. The possible significance of the production of this vitamin in the rumen is discussed.

¹ Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. This work supported in part by the Wisconsin Alumni Research Foundation.

² We are indebted to Merck and Co., Inc., Rahway, N. J., for crystalline vitamins and the vitamin B₁₂ concentrate and to Dr. B. L. Hutchings of the Lederle Laboratories Div., American Cyanamid Co., Pearl River, N. Y., for synthetic folic acid.

³ Departments of Animal Husbandry and Biochemistry.