340 NUTRITION OF FARM ANIMALS 



for growing or milking animals, in which a storage of ash in the 

 product occurs. For the simple maintenance of mature an- 

 imals, however, which is the topic under discussion, the question 

 whether the small amount of lime present, for example, is ad- 

 equate depends upon the rate at which lime is being lost from 

 the body. If this loss could be reduced to zero, a feeding stuff 

 containing no lime whatever would seem to be adequate for 

 maintenance so far as that substance is concerned. In general, 

 whether a feeding stuff or ration is to be regarded as containing 

 an insufficient amount of some ash element for maintenance de- 

 pends largely on how it affects those body functions which de- 

 termine the rate of excretion of that element. 



431. Acid and basic ash. It is usually considered that the 

 most important relation of feed in the respect just mentioned 

 is that which it bears to the maintenance of neutrality in the 

 body fluids. Feeding stuffs or rations containing in assimilable 

 form much sulphur or phosphorus, for example, tend to cause 

 the production in the body of corresponding amounts of sul- 

 phuric and phosphoric acids which must be neutralized. On 

 the other hand, feeding stuffs containing large proportions of 

 the bases tend to have the opposite effect. The relation of acid 

 to basic elements has, therefore, an important bearing upon the 

 suitability of a feeding stuff for ash maintenance. 1 



Feeding stuffs differ widely in this respect. In general it 

 may be said that the concentrates contain relatively much 

 phosphorus and sulphur, little calcium and only moderate 

 amounts of potassium and sodium, while the roughages, es- 

 pecially those of better quality, are rich in calcium and alkalies 

 and low in sulphur and phosphorus. A definite measure of 

 these differences as related to the maintenance of neutrality in 

 the body is obtained by converting the percentages of the 

 several ash ingredients into chemical equivalents. 



Alfalfa hay, for example, according to Henry and Morrison, 2 

 contains in one kilogram the amounts of ash ingredients shown 

 in the first column of the following statement. Dividing 



1 Evidently the sulphur and phosphorus present in organic combination must be 

 included in such comparisons as well as the elements present in the form of electro- 

 lytes. In the older ash analyses the sulphuric acid represents only that part of the 

 sulphur remaining after the material has been ashed, which, as is now known, is but 

 a small part of the total sulphur. 



2 Feeds and Feeding, isth Ed., p. 672. 



