USE OF LITTEB. 115 



The composition of the excreta of 'animals is liable to such 

 enormous variations in composition, according to the nature of 

 the food and other conditions, that it is almost impossible to 

 give any average figures. 



As showing how variable the utilisation of the ingredients of 

 food may be in the case of animals living under different 

 conditions, the following table may be quoted from Warington* 

 as giving the destination of the nitrogen supplied in the food. 

 For every lOOIb. of nitrogen consumed : 



Obtained as Voided as Voided as In total 

 carcass or milk. dung. urine. excrement. 



Horse at rest ... none 43'0 57*0 100 



work ... none 29-4 70*6 100 



Fattening oxen ... 3*9 22-6 73'5 96'1 



sheep... 4-3 16-7 79-0 95-7 



pigs ... 14-7 25-0 60-3 85-3 



Milking cow ... 24*5 18-1 57'4 75-5 



Calf fed on milk... 69-3 5-1 25-6 30-7 



As has already been stated, the dung consists mainly of the 

 undigested portion of the food mixed with a certain amount of 

 the residue from the bile and other digestive fluids. It is 

 therefore to be expected that the amount of plant food, say 

 nitrogen, in the solid excrement will be greater the less 

 digestible the food consumed. 



The litter and loastc food. Litter serves several useful pur- 

 poses. Besides the obvious advantages attending its use from 

 the point of view of cleanliness and comfort for the animal, it 

 also fulfils several other functions. It greatly increases the bulk 

 of,the manure, rendering it more porous and therefore better 

 able to retain the valuable liquid portion of the excreta, it pro- 

 vides a large amount of carbonaceous matter which will eventu- 

 ally be converted into humus, and it adds its quota of plant 

 food, small though it be. It has a considerable effect upon the 

 various fermentative changes which the excreta of animals so 

 readily undergo, both by its influence on the porosity and 

 consequent admission of air and also by the micro-organisms 

 with which it is said to be often abundantly supplied. 



* " Chemistry of the Farm." 



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