[Rapid biological method for assessing D-vitamin supply of chicks].

A segment of the small intestine of chicks turned inside out and pulled on a glass rod was placed into a buffer solution. The Ca2+ consumption from the solution was monitored, using the color murexide reaction. The Ca2+ binding during the first 5 min was much higher in the chicks well supplied with D-vitamin than in the D-vitamin deficient chicks. The level of binding was determined by the content of specific calcium-binding protein in the intestinal mucosa. A close correlation between the dosage of D3-vitamin and the amount of Ca2+ consumed by the intestine from the solution and bound with the mucosa was established. These findings together with the simplicity of the procedure suggest that measurement of the calcium binding capacity of an intestinal segment can be used as a rapid method of assaying the D-vitamin status of the animal.