The effect of high phosphorus intake on calcium and phosphorus retention and bone turnover in growing lambs

Growing lambs were fed diets that just met their requirement for Ca but which supplied either 1 or 3 times their requirement for P and the effects on Ca and P retention and on bone turnover were monitored. Feeding the high P diet had no adverse effect on Ca and P absorption or retention or on bone formation rate. Bone resorption rate was a little higher in lambs fed the high P diet but there were no differences between treatments in plasma parathyroid hormone, 1,25-dihydroxyvitamin D3 or 25-hydroxyvitamin D3 levels or in bone mineral content. It would appear from these results that feeding diets that are rich in P is unlikely to have any adverse effect on skeletal mineralization in the lamb provided that their minimum requirement for Ca is met.