INFLUENCE OF DIETARY CONCENTRATION OF CALCIUM AND PHOSPHORUS ON THEIR RETENTION IN BODY OF GROWING PIG

Three gilts and three castrated males weighing 23 kg live weight were given four semi-synthetic diets containing increasing amounts of Ca and P. The Ca and P contents (% dry basis) and Ca:P ratios for the four diets were A, 0.30, 0.38, 1:1.27; B, 0.58, 0.68, 1:1.17; C, 0.94, 1.13, l:l.20; D, 1.16, 1.47, 1:1.27. Each animal was slaughtered at 41 kg live weight and the whole body contents of Ca and P determined. Six pigs were slaughtered at 23 kg live weight and their bodies also analysed for Ca and P contents. Dietary concentration of Ca and P did not influence rate or efficiency of live weight gain nor carcass characteristics. Net retention of Ca and P increased with increasing dietary concentration of these elements. Analyses of isolated femurs suggested that optimal mineralization of the bone was associated with a net retention of 8.2 g Ca/kg live weight gain. The data were used to calculate a value of 32.9 mg/kg live weight/day for the endogenous loss of Ca in pigs of 23-41 kg body weight. The values have been used to compute a mineral requirement of dietary calcium which is in excellent agreement with that derived from estimates in the literature. © 1969, Cambridge University Press. All rights reserved.