Biological Assay of Thiamin with Chicks

Abstract

A method is described for the assay of thiamin with chicks, using a basal diet consisting principally of polished rice, fish meal and autoclaved yeast. A response curve was constructed in which the level of thiamin added to the diet is compared with the ‘polyneuritic mortality index,’ the latter value being expressive of the degree of protection afforded by a suboptimal level of thiamin fed during the assay period of 28 days. The thiamin requirement of the chick was estimated as being between 130 and 150 micrograms of thiamin chloride hydrochloride per 100 gm. of diet for prevention of polyneuritis under the conditions studied. The thiamin content of the polished rice used in the basal diet was found to be about 0.4 micrograms per gram. A growth essential for the chick, absent from autoclaved yeast, was found present in polished rice.