Effect of Dietary Calcium and Phosphorus Level upon Calcium, Phosphorus and Nitrogen Balance in Swine

Three metabolism trials were conducted to determine the effects of dietary calcium and phosphorus level upon calcium, phosphorus and nitrogen balance in growing swine. The nine pigs in each trial averaged 22.6, 25.2 and 26.5 kg initially for trials 1, 2 and 3, respectively. The diets contained three levels of calcium and three levels of phosphorus and were rotated among the pigs in the three trials. Feed intake was adjusted to metabolic size. Within the limits of the calcium and phosphorus levels used in this experiment, calcium to phosphorus ratios were not as important in the utilization of these two elements as dietary levels per se. The optimum calcium to phosphorus ratio varied with the level of calcium and with the level of phosphorus in the diet. The utilization of calcium appears to be less affected by calcium to phosphorus ratios than is the case with phosphorus utilization. Urinary calcium decreased while calcium retention increased as dietary phosphorus increased.