Vitamin B12 in rumen wall and liver

Samples of liver, rumen wall, and rumen mucosa (rumen wall stripped of its muscle) were assayed for vitamin B12 by specific and nonspecific methods. Mean differences between methods were negligible. Rumen mucosa and rumen wall contained approximately 10% as much vitamin B12 as liver. The B12 contents of liver and rumen mucosa were correlated whereas those of liver and rumen wall were not.