Abstract
The Ca retention from diets containing 0.011% Ca and 0.018-0.113% P has been studied for rats from 1 mo. to 2 yrs. of age. Young rats showed a Ca balance with 0.059% P in the diet, and the balance was negative with lower P, positive with higher P in the diet. Ca absorption decreased as the age of the rats increased. The retention of P paralleled that of Ca. In young rats, the soft tissues take precedence over bone in the competition for P.