The Effects of Age upon Calcium Utilization and Maintenance Requirements in the Bovine1

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Abstract
Concurrent chemical and radiocalcium balance studies were carried out with thirty-four Hereford cattle ranging in age from 10 days to 190 months. Absorption and/or true digestibility values were greatest in young animals, decreased rapidly to sexual maturity then more slowly to maturity, and again decreased in the aged animals. Daily endogenous fecal calcium increased with increased age and body weight from 0.42 grams at 10 days to 3.3 at 6 months to 8 grams at maturity. The quantity, milligrams per kilogram body weight of endogenous fecal calcium, was remarkably constant from one month of age to maturity. However, the low level in 10 day old animals and the slightly higher level in aged animals indicated a trend toward an increase with age. Maintenance requirements per 100 pounds body weight calculated from the endogenous and true digestibility values ranged from 0.5 grams at 10 days to 2 grams at six months and remained relatively constant to maturity. Procedure described should be useful for the estimation of the true digestibility of calcium from the various organic and inorganic sources with animals of different ages under various experimental conditions. Copyright © . .

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