NEGLECTED POINTS IN STOCK FEEDING. 601 



In cows' milk, on the average, there are about 0'17 per cent, of 

 phosphorus pentoxide and 0'15% of hme; these figiu-es being in the 

 ratio of about 100 of phosphorus pentoxide to 89 of hnie. 



It would probably be safe to assume, therefore, that for proper 

 bene nutrition the whole food of the animal should contain about 

 equal Aveights of phosphorus pentoxide and lime. 



Now, in the two foodstuffs so largely used for horses and mules 

 in South Africa, the proportions are very different. 



In oaten hay, according to Wolff's analyses, the ratio is 100 of 

 phosphorus pentoxide to 77 of lime, while in maize grain it is 100 : 4. 



According to the figures quoted by Warington, for the whole 

 oat plant the ratio is 100: 60, while in many samples of oaten hay 

 grown in South Africa the writer finds an average of 100:51. 



It is thus evident that the usual diet of South African horses and 

 mules provides a large excess of phosphoric acid to lime. 



Now, in Europe, oats are largely used, and highly valued as food 

 for horses, but they are nearly always supplemented by hay — either 

 meadow hay or clover hay, both of which, as will be shown, contain 

 a large excess of lime over phosphorus pentoxide. Unfortunately, so 

 far as can be ascertained, no direct experiments upon horses and 

 mules to elucidate the effect of a prolonged use of such a diet have 

 been made, but in 1891 Weiske experimented with rabbits on these 

 lines, and found that animals fed on oats alone produced small, 

 brittle bones, while exactly similar rabbits fed upon hay or upon a 

 mixture of hay and oats develope.d normal skeletons. 



The writer is fully persuaded that the susceptibility to the 

 disease, if not the disease itself, is due to the use of a diet containing 

 a relatively high pi'oportion of phosphorus pentoxide and a low pro- 

 portion of lime, and that it is not so much the deficiency of South 

 African-grown oaten hay in lime and phosphoric acid as compared 

 with European produce, but the fact that the diet in Africa is so 

 restricted to oaten hay or oaten hay and maize that causes the 

 trouble. 



The view that bone diseases are due to deficiencies of the food 

 in lime and phosphates is very wide spread, but it is not realised that 

 it is the proportion in which these occur that is important. A striking 

 example of error in the popular views on this point is furnished in 

 the case of wheat bran. This material is widely regarded as particu- 

 larly rich in bone-forming constituents, but from the point of view 

 here adduced should be very ill adapted for bone nutrition, since it 

 contains an overwhelming excess of phosphorus pentoxide as com- 

 pared to lime, the actual proportions being, on the average, about 

 3 '3 per cent, of the former to 0'3 per cent, of the latter, or in the 

 ration of 100 to 9. This is actually confirmed by the prevalence of 

 a peculiar bone disease resembling in some respects ostei'oporosis, and 

 known as " bran rachitis," " bran disease," or '" millers' horse rickets," 

 among horses fed largely upon bran. 



