Calcium and Phosphorus Levels Related to T H E D E V E L O P M E N T of Phosphate Urinary Calculi in Sheep 1

A HIGH incidence of phosphate urinary calculi in sheep has been associated with the feeding of rations containing dibasic potassium phosphate (Lindley et al., 1953; Elam et al., 1956, 1957). Further, Lindley et al. (1953) observed elevated plasma phosphorus levels under these conditions. Emerick et al. (1959) observed high plasma phosphorus levels in lambs subsequently afflicted with urinary mineral deposits although not receiving excessive dietary phosphorus. Schneider et al. (1952) reported that supplementation of high-phosphorus rations with a source of calcium reduced the incidence of urinary calculi. While calcium supplementation of high-phosphorus rations has been shown to produce lower plasma phosphorus levels (Lindley et al., 1953; Elam et al., 1959), it has not always reduced the frequency of urinary calculi occurrence (Taysom et al., 1951; Lindley et al., 1953). The experiment described herein was conducted to determine the relative effectiveness of various dietary calcium and phosphorus levels in inducing urolithiasis in sheep.