Rumen Synthesis of the Vitamin B Complex. †

Work reported by McElroy and Gross 1 indicates the ability of sheep to synthesize several members of the vitamin B complex in the rumen. Significant increases in the vitamin content of rumen ingesta were found in comparison to the amounts in the ration fed. The vitamins determined were thiamin, riboflavin, pyridoxine, and pantothenic acid. The ration used consisted of washed casein 5, washed sardine meal 6.7, cerelose 11.0, corn starch 10.6, mineral mixture 3.0, and dried plain beet pulp 63.7%. In a later report 2 McElroy and Goss obtained similar results when feeding this ration to a cow with a rumen fistula.

At the time the above work was being reported a similar experiment was under way at this station. The animal used was a heifer calf with a rumen fistula. The ration fed consisted of acid-washed casein 4, urea 1.0, cod liver oil 1.0, salt mixture 3.0, corn molasses 10.0. corn starch 71.0, and bleached wood-pulp 10.0%. The calf was fed daily at 8 A.M. and 8 P.M., receiving 2 pounds of ration per feeding. After the calf had received this ration for several weeks the rumen contents were sampled on alternate days at 2 P.M. until about 20 kilos of wet material had been obtained. The size of the samples was approximately 2 kilos of wet material (12-15% dry matter). Immediately upon sampling, the material was diluted with 95% ethyl alcohol to a final concentration of 45-50'% and placed in a cold room (35°F) in order to stop bacterial action. Two to 3 days later this material was placed in enamel-lined pans and dried in a drying room for 24 to 40 hours at a temperature of 45 to 50°C. After grinding these samples were again stored in the cold room and removed as needed. The analyses were assays on a composite sample.

The components of the vitamin B complex assayed for were: thiamin, riboflavin, nicotinic acid, pyridoxine, pantothenic acid, and biotin. The methods of assay used were as follows: Thiamin, chick; 8 riboflavin, microbiological; 4 nicotinic acid, chemical; 5 pyridoxine, rat; 6 pantothenic acid, microbiological; 7 biotin, microbiological. 8 The results are given in Table I.

From Table I it is readily seen that an appreciable synthesis of all members of the B complex assayed for occurs.