Observations on the mineral metabolism of pullets. IV

Abstract

1. Phytic acid in cereals and in certain rations based on cereals was incompletely hydrolysed during its passage through the intestinal tract of the pullet.2. The percentage recovery in the droppings of phytic acid in a ration (24·2%) based on cereals plus extracted soya bean meal was considerable even when the ration included no calcium supplements. Both calcium carbonate and tricalcic phosphate greatly increased the percentage recovery. A supplement of calcium carbonate led to a somewhat higher recovery of phytic acid than a supplement of tricalcic phosphate containing the same amount of calcium.3. The recovery of phytic acid tended to be somewhat higher in laying birds than in non-laying birds; this may have been associated with decreased amounts of calcium in the alimentary tract due to the demands for egg-shell formation.4. The observations of Knowleset al. on the composition of the droppings of non-laying pullets on certain rations were confirmed; it was found, however, that their rule connecting the amounts of carbonate, calcium and phosphorus in such droppings did not extend (a) to the case of laying pullets, or (b) to certain other rations of wider Ca/P ratio.5. The interpretation of the rule enunciated by Knowleset al. to mean that calcium and phosphorus are normally excreted by the pullet as dicalcium phosphate and calcium carbonate was shown to be untenable in view of the fact that the droppings may obey this rule and yet contain considerable amounts of phosphorus in organic combination.