MAINTENANCE REQUIREMENTS OF MATTER 347 



TABLE 64. ASH OF HAY CAUSING RICKETS 



Such a hay is relatively deficient in calcium and phosphorus 

 and would presumably be improved by the addition of calcium 

 phosphate, while the addition of calcium carbonate would 

 probably be unnecessary, since the hay contains an excess of 

 basic over acid ingredients. In addition, however, to its de- 

 ficiency in calcium and phosphorus, it shows a misproportion 

 of potassium to sodium, which, as already explained, would 

 tend to increase the excretion of calcium phosphate unless 

 sodium salts, particularly the chlorid, were added. 



In the mixed rations of herbivora, however, direct addition 

 of mineral matter is seldom likely to be necessary unless rough- 

 age of abnormal quality is employed. Usually the surplus of 

 bases in forage crops will more than balance the surplus of 

 acid elements in the concentrates used, while the common salt 

 ordinarily given as a condiment will more than balance any 

 probable excess of potassium in the rations. Unusual rations, 

 such perhaps as very heavy grain rations, those containing an 

 unusual proportion of protein, or those made up of unusual 

 feeds may form an exception to this general rule and require 

 special consideration. In the case of swine, such a balancing 

 of one feeding stuff against another as regards ash ingredients 

 is less practicable, and the securing of a proper balance needs 

 more attention. Until, however, more determinations of the 

 actual ash balance of different species on different classes of 

 rations are made (435) it is hardly possible to state with any 



