Studies on the Chick Assay for Vitamin D

Abstract

A LARGE part of the research on vitamin D for poultry is directed at the present time toward the simplification and speeding up of the tibia ash method of assay. Among the disadvantages of this method are the dissection and cleaning of the bones and the lengthy extraction period. These difficulties are all inherent in the tibia ash method, and if they are to be eliminated the method itself must be modified. The use of toe rather than tibia ash as a criterion of calcification as proposed by Baird and MacMillan (1942) would go far in overcoming these difficulties. These authors have shown that toes may be expected to give approximately the same results as tibiae in the interpretation of assays. However, before the toe method can be generally adopted it is necessary to obtain an accurate estimate of its precision (cf. Bliss and Cattell, 1943) as compared with the . . .