Bethke and associates (1933) and Dunlop (1935) conclude that growing pigs require approximately 0 - 6 percent P in their rations and that maximum growth is obtained with a Calcium-phosphorus ratio
between 1:1 and 2:1. Bethke et al. furthermore state that as the proportion of Ca to P exceeded 3:1 the pigs became more rachitic and their vitamin D requirements increased. Our own experience
here has been that while the ratio of Ca to P is undoubtedly important, osteodystrophic diseases may be produced in cattle, and probably in other species, merely by limiting the Ca or P intake or both, even when the ratio of these two constituents to one another was normal, when judged by the usually accepted standards; these observations have been summarized and discussed in the light of the findings of other investigators by Theiler and others (1936). Shohl and Wolbach (1936) report similar results with rats.