THE FEEDING OF ANIMALS 177 



The seeds of all plants are tlms relatively poor in lime and rich 

 in phosphorus pentoxide as compared with the foliage, while 

 even the whole plant, in the case of the cereals, contains far 

 more of the latter than the former. 



The importance of the diet being rich in ash constituents 

 in connection with bone formation has long been realised, but 

 the fact that it is the ratio of lime to phosphoric acid that is 

 important has not hitherto been recognised. Thusj bran is 

 widely regarded as being rich in *' bone-forming " material, 

 but from the point of view here expressed it should be very- 

 unsuitable for the development of bone, since analysis shows 

 it to contain about 3*3 percent, of its dry weight of phosphorus 

 pentoxide, but only 0*3 per cent, of lime, i.e., only 009 of 

 lime to I'O of phosphorus pentoxide. Practical experience 

 shows that animals fed very largely upon bran are prone to 

 contract a curious bone disease known as " millers' horse 

 disease " or " bran rachitis." 



The feeding of horses and mules upon a diet exclusively 

 composed of oat-hay or oat-hay and maize, a ration containing 

 a great excess of phosphorus pentoxide over lime, is believed, 

 by the writer, to be the main cause of the prevalence of a 

 bone disease, '* osteoporosis," in many parts of South Africa. 



Another function of the ash constituents of food is the supply 

 of certain substances required by the animal in secreting various 

 digestive juices, e.g., chlorine for the production of hydrochloric 

 acid in the gastric juice, potassium compounds which are 

 present in the saliva, gastric juice and other secretions. In 

 some countries, these substances are deficient in the natural 

 food available, and it is then found necessary, in order to 



