24 The Feeding of Animals 



ing less than one-sixth of the animal to be built from 

 elements that have, in part, a commercial value for 

 crop production, which is the fundamental considera- 

 tion in animal husbandry. 



As has been stated previously, one of these ele- 

 ments, which in its various compounds bears a market 

 value, is nitrogen. The others having commercial im- 

 portance belong to what is termed the ash of the plant 

 or animal. For this and other reasons it is desirable 

 to consider the elements found in the ash or mineral 

 portion of the animal body. We will return for this 

 information to the analysis of a fat ox made by Lawes 

 and Gilbert. These investigators found that the ash, 

 constituting 8.8 per cent of the dry substance of the 

 entire body, was made up as follows: 



Per cent 



Phosphorus 1.53 



Calcium 2.80 



Potassium . .26 



Sodium 20 



Magnesium 07 



Oxygen, combined with the above 3.29 



Silicon, sulfur 65 



8.80 



Of the elements other than oxygen which appear in 

 the ash, phosphorus and calcium take a leading place as 

 to quantity, although sulfur, potassium and sodium are 

 essential, even if present in relatively small amounts. 

 Phosphorus, potassium and calcium have a commercial 

 pi'ominence in their agricultural relations, a fact which 

 is to be considered chiefly in their uses as plant -foods. 



