Levels of calcium and phosphorus for growing-finishing swine.

Abstract

Three experiments were conducted with a total of 190 Yorkshire × Hampshire crossbred pigs (initial weight 35.0, 27.4 and 22.4 kg. for Experiments 1, 2 and 3 respectively) to determine the effect of dietary levels and ratios of calcium and phosphorus on gain, feed intake, feed conversion, bone weight, bone breaking strength (BKS), percent bone ash and incidence of atrophic rhinitis (AR) in growing-finishing swine. There were no significant differences in average daily gain, feed intake or feed conversion due to variation in dietary calcium or phosphorus levels in Experiment 1. BKS was significantly (P<.005) higher for the high level of phosphorus and interrelated level of calcium (Diet D). Experiment 2 showed an over-all significant (P<.005) difference in BKS and bone weight due to experimental treatment. BKS and bone weight were also significantly (P<.005) higher in pigs fed diets with 0.65% calcium than for those fed 0.35%. BKS and bone weight had a correlation of 0.82% for Experiment 2. In a third experiment, pigs were fed diets varying in levels of phosphorus and amounts of inorganic phosphorus. Increasing phosphorus in equal increments from 0.30% to 0.70% of the diet improved average daily gain in a linear manner. Also, the linear effect of levels of dietary phosphorus on feed intake was significant (P<.005) with the highest intake at the 0.60% level. BKS was significantly affected by dietary treatment (P<.05). The linear component of the effect of phosphorus levels on BKS approached significance. Bone weight followed the same trend as BKS with a correlation of 0.66. The results of these experiments show that calcium and phosphorus levels and ratios can vary considerably without significantly affecting daily gain and feed conversion of pigs. Levels and ratios of the two elements do affect bone formation as shown by BKS and bone weight data. In these experiments, bone weight seemed to be nearly as good a measurement of bone formation as BKS. Within the levels and ratios of calcium and phosphorus studied, there was no relationship between dietary calicum and phosphorus and atrophic rhinitis in growing-finishing swine.