Abstract
Pyridoxine requirement of White Leghorn chicks was studied, feeding two strains of day-old male chicks with vitamin B_6-free purified ration containing graded levels of pyridoxine hydrochloride. Maximum growth of a strain of chicks was produced with the ration containing 6.2 mg/kg of pyridoxine hydrochloride and that of the other strain 8.2 mg/kg. Thus it was concluded that vitamin B_6 requirement of our chicks was approximately twice as high as that recommended in U.S.A. Although the data in U.S.A. with White Leghorn chicks and broiler-type chicks indicate the similer requirement of about 3.5 mg/kg, differnce in requirement of the two strains in this experiment was highly significant. Against the old description that vitamin B_6 deficiency lowers the efficiency of feed utilization, feed efficiency was maintained fairly constant until vitamin B_6 content reached as low as 2.2 mg/kg. Vitamin B_6 contents of various feedstuffs common in this country and of cow's and sow's milk were determined microbiologically using Saccharomyces carls-bergensis.
