Gastrointestinal Sites of Absorption and Endogenous Secretion of Calcium and Phosphorus in Dairy Calves.

Abstract

Eight Holstein male calves, 12 to 15 weeks of age were given Ce144 twice daily in their feed for 7 days at which time equilibrium was reached in fecal concentration. The animals were slaughtered and ingest a samples were taken from 12 sites throughout the gastrointestinal tract. The ratio of Ce144 to Ca or P was calculated to determine net absorption or net endogenous secretion of these elements at various sites. Secretion of P into the rumen and omasum and absorption of Ca and P from the abomasum are indicated. The sites of Ca absorption are not always associated with P secretion. Appreciable secretions of Ca and P in the lower tract are not present or they are balanced by an equal absorption.