STUDIES ON THE ACTIVITY OF SYNTHETIC BIOTIN, ITS ENANTIOMORPH, AND RELATED RACEMIC FORMS FOR THE CHICK

Abstract

Biotin from natural sources has been shown to prevent a scaly dermatitis of the feet and shanks (1, 2), to be involved in the prevention of perosis (3, 4), and to promote growth in biotin-deficient chicks (l-5). Experiments in this laboratory with chicks fed purified diets containing dried raw egg white have indicated that the above deficiency signs can be prevented by administration of synthetic biotin (6), while Lbiotin (7, 8) and dl-allobiotin (7, 8) appear to be without activity I;n these respects. The basal diet used in the tests contained dextrose 43.5, dried raw egg white 15, purified casein 10, cellulose 10, wheat bran 10, calcium gluconate 5, mineral mixture 3.5, glycine 1.5, wheat germ oil 0.5, fish liver oil (400 D) 0.5, bcystine 0.2, choline chloride 0.15, inositol 0.1, p-aminobenzoic acid 0.03, niacin 0.01, calcium pantothenate 0.004, pyridoxine 0.002, riboflavin 0.002, thiamine 0.002, and menadione 0.0002 per cent. The usual procedure has been to rear day-old white Leghorn chicks for 1 week on a commercial type of starting ration, to sort them carefully into groups of equal mean body weights and growth rates, and then feed the basal diet with or without added biotin for a 2 week period. The various biotin compounds were incorporated in aqueous solution directly into the diets, which were freshly prepared each week and fed to groups of five to seven chicks each. Electrically heated all metal battery brooders with wire floors were used throughout. In preliminary tests it was noted that chicks receiving about 1 mg. of natural biotin’ added per kilo of basal diet grew more rapidly than did the chicks receiving only the basal diet. The differences in weight gain were relatively large at 3 weeks of age, when the first signs of dermatitis appeared in the chicks fed the basal diet. Comparative effects of natural and synthetic biotin upon chick growth are shown in Table I. It is seen that dl-allobiotin was without activity, whereas dl-biotin and synthetic biotin possessed activity comparable to that exhibited by the natural substance. Activities of synthetic biotin and its enantiomorph were investigated