liO MANUAL OF CATTLE-JFEEDIN-a. 



we know liow much nitrogen lias entered into tlie system, 

 while the urinary nitrogen tells us how much has left it ; 

 the difference between the two, of course, is the gain or 

 loss of nitrogen by the body, and since the albuminoids 

 contain, on an average, 16 per cent, of nitrogen, this quan- 

 tity, multiplied by 6.25, gives the gain or loss of diy pro- 

 tein. If it is desired to know the amount of fresh flesh, 

 with its normal content of water and ash, which has been 

 gained or lost, this also can be calculated from the average 

 composition of the latter. Voit,* in all his experiments, 

 reckons, on the basis of his own and other analyses, that 

 fresh iiesh, free from fat, has the following composition : 



Water 75.9 per cent. 



Ash 18 '' 



Dry matter 22 8 *' 



100.0 

 Nitrogen 3.4 ' « 



Other observers have obtained results differing slightly 

 from this, but not sufficiently to be of serious consequence, 

 and since so many experiments by Yoit and others are 

 calculated on this basis, it will be convenient to follow the 

 example of this eminent investigator. Assuming, then, 

 that fresh, fat-free flesh contains 3.4 per cent, of nitrogen, 

 we have only to multiply the gain or loss* of nitrogen ob- 

 served in our experiment by 29.4 (3.4 per cent, x 29,4 

 = 100 per cent.) to learn how much flesh our animal has 

 hiid on or destroyed, while similar calculations on the total 

 urinary nitrogen will inform ns of the total amounts, re- 

 spectively, of protein or of flesh decomposed in the vital 

 processes. 



m u 



Ernahrung des Fleischfresscrs," 1800, p. 304, and Zeitschiift fur 

 Bjologie, 18CG, p. 468. 



