Determination of the Fate of Phosphorus in the Laying Hen by Means of Radiophosphorus (P 32 )

Abstract

Bone meal in a laying mash was replaced by 700 mg. of Ca3(PO4)2 with a P32 activity of approx. 105 disintegrations/min. A hen was given one feeding of P32. The eggs laid were hard boiled, and separated into shell, white, and yolk. After wet ashing, the P was converted to magnesium pyrophosphate and its activity detd. After allowing for self-absorption of the sample and decay of the P32, the percentage of phosphate in the different parts of the egg could be detd. Approx. 5% of the P fed as calcium phosphate appeared in the egg, over 80% being in the yolk. It was also found that if a hen were fed the same dose of active Ca3(PO4)2 each day, the amt. of labeled P appearing in each egg reached an equilibrium value equal to the total previously measured, provided the hen was laying at a fairly uniform rate. P fed to the hen still appeared in eggs a month later. It was derived from muscles and bones, since the tibia, 40 days after feeding, showed approx. 7% of the P fed.