7 8 GROWTH 



of corn, and it was shown la that, at least for swine, protein is the 

 first limiting factor, and mineral constituents the second. 



As to the individual mineral elements, it was well known 

 from the first that, to a certain extent at least, these elements 

 could be supplied in inorganic form. The question has been 

 raised, however, as to the possibility of entirely supplying the 

 requirement for these materials in the form of inorganic salts. 

 Many investigators have supposed that at least a certain quan- 

 tity of phosphorus must be supplied in organic combination. For 

 that reason considerable attention has been given to the lecithins, 

 nucleins, and phytates, as sources of phosphorus. Rohmann, for 

 example, stated 11 many years ago that the animal organism does 

 not have the power of synthesizing the organic phosphorus con- 

 stituents of the body. 



Several years ago the Wisconsin Station 12 attempted to solve 

 this problem. They undertook a study of the ability of the ani- 

 mal organism, swine, to use inorganic phosphorus in forming 

 new growth. In all, five groups of animals were used. Lot I re- 

 ceived the basal ration composed of rice, wheat gluten, and 

 washed bran. Lots 2 and 3 received the basal ration, with the 

 addition of various quantities of calcium phosphate. The ration 

 supplied Lot 4 was made up of rice, wheat gluten, and un- 

 washed bran. A ration containing corn, oats, shorts, and oil meal 

 was supplied the fifth lot, as an additional control. 



At first all groups did about equally well, but in about three 

 months the lot receiving the basal ration began to show signs of 

 distress. There was soon pronounced weakness of the hind 

 quarters, the animals were unable to stand, and at the same time 

 there was a considerable loss in weight. One of these pigs was 

 killed for examination. The most important abnormality noted 

 concerned the appearance of the bones, which were spongy and 

 loose in texture. The specific gravity was less than one, and the 

 ash content, on a moisture-free basis, was only about 33 per 

 cent, while the ash content of normal bones is about 54 per cent. 



