Influence of high proportions of dietary phosphate on the bone of growing swine

Young swine of mixed breed were fed complete diets containing calcium and phosphate in the weight ratios of 1:1 (control), 1:2, or 1:3, for six months. Extensive serum chemical and endocrine analyses were conducted monthly during the course of the experiment. A double label tetracycline (TC) regimen was administered before autopsy, and from the deposited labels several parameters of tissue-level bone turnover were found. Also, an analysis using the Quantimet-720 was done on microradiographs of the bone samples. In the animals treated with an abnormally high level of phosphate in the diet, more bone surface was found to be occupied by both double and single TC labels. The apposition rate at these sites, however, was found to be unchanged from controls