Bioavailability of Phosphorus from Defluorinated and Dicalcium Phosphates and Phosphorus Requirement of Calves

Bioavailability of P from defluorinated phosphate and dicalcium phosphate and the P requirement were studied with 63 male Holstein calves. A P depletion diet containing .08% total P on a dry matter basis was fed to all animals for 4 wk beginning at 6 wk of age and 61 kg weight. Calves developed typical signs of P deficiency. The depletion period was followed by a 6-wk experimental period in which the same depletion diet was used as a control. Phosphorus from each of the two sources was added to make diets containing .14, .20, and .32% total P. Source of supplemental P did not affect weight gains, feed consumption, feed efficiency, serum inorganic P, serum alkaline phosphatase, or bone ash.