At the microbioassay of vitamin B group (vitamin B_<12>, pantothenic acid, folic acid and vitamin B_6) in formula feed, the influence of feed additives (arsanilic acid, furazolidone, sulfaquinoxaline and arsenobenzene) on the assay values were studied. As the results, it was observed that those influences on each assay microorganism varied according to the kinds of additives. But, it was found that there was no influence of additives on the routine microbioassay of vitamin B group in formula feed.
