Food Requirements of Animals. 255 



It is essential that the maintenance ration should supply enough 

 protein to replace the daily waste of the nitrogenous tissue. Only 

 a small amount is necessarily destroyed by the resting animal; 

 but there is a constant waste, and unless this is replaced the 

 animal will die of starvation. It is plain then that the demands 

 upon food for maintenance purposes are mainly for the produc- 

 tion of muscular energy and heat. Armsby found that a supply 

 of 0.6 Ib. of digestible protein per day was sufficient for the 

 permanent maintenance of a 1000 pound ox, receiving a ration 

 with a nutritive ratio of 1:11. 



The thorough studies of Zuntz on the horse have shown that a 

 1000 pound animal can be maintained on 6.4 pounds of available 

 nutrients, provided the total ration does not contain more than 

 three pounds of crude fiber. This means that the nutrients must 

 come from hay and grain. Grandeau places ths maintenance re- 

 quirement for the same weight of animal at 7 to 7.8 pounds of 

 digestible organic matter, including 0.45 pound of digestible pro- 

 tein. 



There are few experiments with sheep, but according to German 

 experiments, 13.8 pounds of digestible organic matter, including 

 1.0 pound of digestible protein, per 3000 pounds live weight are 

 required to maintain proper conditions. Its continued produc- 

 tion of wool, higher temperature and smaller size make the re- 

 quirements for this animal somewhat more liberal than with the 

 horse or ox. 



It is clear then that 90 per cent or more of a maintenance ration 

 may consist of carbohydrates or materials used solely for fuel. 

 This makes it easy to supply this ration from the home grown 

 products. The quantity of available nutrients consumed is small 

 and may largely be made up of coarse material, such as corn 

 fodder and hay. Again, the low protein requirement and the pos- 

 sibility of a wide nutritive ratio, characteristic of home grown 

 products, makes its selection easy. 



Requirements for labor. As the horse is practically the only 

 animal used in this country for draft and road purposes, it will 



