X.] ENERGY REQUIRED BY ANIMALS 197 



the consumption of food to repair the loss ; hence the 

 truth of the old saying that shelter is as good as a meal. 

 Heat may also be required, and, therefore, food consumed 

 in raising the temperature of the food and water to the 

 body temperature, and this may be considerable when 

 large quantities of very cold water, or roots which 

 contain nearly 90 per cent, of water are consumed 

 at a freezing temperature. This, however, would only 

 affect animals on a maintenance ration when the food 

 is reduced to the minimum necessary to keep the 

 animals warm ; on fattening rations there is always a 

 surplus of heat that cannot be utilised in any other way. 

 Leaving, however, such cases out of account, Kellner 

 has drawn up the table from which the diagram. Fig. 

 23, has been constructed, showing the heat value of 

 the food required for the maintenance of store bullocks 

 of various weights when they are kept at rest at a 

 temperature of about 60° F. The solid line expresses the 

 number of calories which the digestible part of the food 

 must give out per day in order to keep the animal in a 

 stationary condition ; these calories can be converted 

 into terms of food by calculating that i lb. of digestible 

 organic matter in an ordinary ration will evolve about 

 1600 calories, and i lb. of starch about 1700 calories ; the 

 dotted line gives the equivalent in starch of the solid 

 line. A fat bullock weighing about 1750 lb. requires 

 about 20,000 calories heat value in its daily food in 

 order to keep it going. The maintenance requirements 

 of a horse are very similar to those of a bullock ; accord- 

 ing to Zuntz, the maintenance ration of a horse at rest 

 must evolve about 12,100 calories per diem, and not 

 more than two-thirds of this energy must be expended 

 in the work of digestion. Sheep have rather greater 

 requirements in proportion to their weight, because of 

 their smaller size and therefore larger proportional 



