100 THE CHEMISTRY OF THE FARM. 



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. 



If we assume that when food is burnt in the body one- 

 fifth of the energy developed may appear as external 

 work, then 1 lb. of digested starch would enable an 

 animal to perform 485 foot-tons of work, 1 lb. of digested 

 albumin 528 foot-tons, and 1 lb. of digested fat 1127 foot- 

 tons of work. 



The recent experience of the use of maize for horses 

 shows that an albuminoid ratio of 1 : 9 is quite sufficient 

 for a labour diet. 



The Fattening Animal. — The character of the fattening 

 process has been more thoroughly studied than the 

 nutrition of young and growing animals. 



For the body to increase in weight it is clear that the 

 food supplied must be in excess of the quantity demanded 

 for mere renovation of tissue, and for the production of 

 heat and work. "When such an excess of food is given, a 

 part of the albuminoids and ash constituents is generally 

 converted into new tissue, while a part of the fat, carbo- 

 hydrates, and albuminoids is stored up in the form of fat. 



As ouly the excess of the food is converted into increase, 

 liberal feeding is, within certain limits, the most economical. 

 If a lamb can be brought by liberal treatment to 150 lb. 

 live weight at one year old, the amount of food consumed 

 will be far smaller than if two years are occupied in 

 attaining the same weight, for the food required for 

 animal heat and work during the second year is clearly 

 saved. 



