122 THE CHEMISTRY OF THE FARM. 



1 : 14 in the case of the ox, 1 : 1 1 in the case of the sheep 

 fed on hay, and the relation is wider still in the case of 

 the sheep fed on straw and mangels. It is advisable that 

 a minimum amount of nitrogenous matter should be 

 given, as any excess over that absolutely demanded pro- 

 motes waste in the system. 



Labour Diet. If external work is to be performed, 

 the body weight remaining unaltered, the quantity of 

 food must be considerably increased, and the food must 

 be of such quality that it may be possible to digest a 

 sufficient amount in the required time. A man doing a 

 fair day's work was found to exhale one-third more 

 carbonic acid than when at rest ; a man doing such work 

 would clearly require one-third more food to maintain 

 the same condition of body. According to Wolffs ex- 

 periments, 1251 foot-tons of work may be obtained from 

 a horse, without altering its body weight, for each pound 

 of digestible organic matter, reckoned as starch, con- 

 sumed over and above the maintenance diet. Wolff 

 found, as has been already mentioned, that it is indifferent 

 whether this extra food is supplied by albuminoids or 

 carbo-hydrates. 



The relative value of the principal constituents of 

 food for the production of heat and work will be found 

 on p. 108, and the relative value of different foods on 

 p. 109. The value of foods containing cellulose is for the 

 horse somewhat less than that shown in the table. 



In constructing a labour diet for horses it is well to 

 combine bran with beans or oats, but not with maize, as 

 both bran and maize are somewhat laxative. 



