RESTRICTED CALCIUM FEEDING VERSUS ZINC SUPPLEMENTATION FOR THE CONTROL OF PARAKERATOSIS IN SWINE

Abstract

It has been amply demonstrated that parakeratosis of swine (Kernkamp and Ferrin, 1953) is adversely affected by feeding excessive amounts of calcium and is greatly alleviated by feeding supplemental zinc (Tucker and Salmon, 1955; Luecke et al., 1956; Lewis et al., 1956). Therefore, two possible methods of controlling this disease are apparent: (1) restricting the calcium intake, or (2) feeding supplemental zinc. A previous report (Lewis et al., 1956) indicated that pigs fed 0.8% calcium (and 0.5% phosphorus) readily developed parakeratosis, but not so rapidly as did pigs fed 1.1–1.4% calcium. Furthermore, the zinc content of a number of body components of swine fed the two levels of calcium with no added zinc was not significantly different. It appeared desirable to compare the effects of feeding a minimum level of calcium (i.e. slightly below the National Research Council (1953) recommendation) on the development of parakeratosis and on the zinc concentration of several body components with those observed from feeding higher levels of calcium. Previous experiments showed that 50 ppm of supplemental zinc in a ration containing 0.8% calcium did not completely prevent parakeratosis, but that 100 ppm of supplemental zinc effectively alleviated or prevented the disease (Lewis et al., 1956). Since zinc might be toxic at high levels it was deemed advisable to establish a safety margin. The purpose of this paper is to present data showing the relative effects of three levels of calcium feeding (0.5%, 0.8% and 1.2%) and two levels of zinc supplementation (100 ppm and