MAINTENANCE DIETS 181 



animal in the form of urine than is contained in the 

 digested food. When the intake and output of nitrogen 

 are the same, an animal is said to be in a condition of 

 nitrogen-equihbrium. This condition of equilibrium 

 can be obtained with a mininum supply of albuminoids 

 only when the food contains a sufficient amount of 

 carbohydrates and fat for the heat requirements of the 

 animal; if the heat-producing food is deficient the 

 albuminoids are partly burnt in the body before they 

 can serve for the renovation of tissue, and a larger 

 quantity is consequently required. An animal cannot 

 be long kept in health with the smallest quantity of 

 albuminoids producing nitrogen-equilibrium, as the 

 growth of hair, wool, hoofs, &c., is always in progress; 

 a truly maintenance diet must thus supply rather more 

 albuminoids than the minimum. Armsby found that 

 a supply of 0"6 lb. of true albuminoids per day was 

 sufficient for the permanent maintenance of an ox of 

 1,000 lbs. weight receiving a diet having an albuminoid 

 ratio of 1 : 11 ; but that when a greater proportion of 

 carbohydrates was given, this amount of albuminoids 

 might be considerably reduced without disturbing the 

 nitrogen-equilibrium, and without, at least for a time, 

 any injurious results to the animal. For an econo- 

 mical maintenance diet an unnecessary excess of 

 albuminoids must be avoided, as the presence of any 

 excess in the system determines a greater demand for 

 food. The amount of albuminoids needed becomes 

 larger when the animal receives an increased supply 

 of drinking water. The demand for albuminoids 

 stands in relation to the weight, and not to the surface 

 of the animal. 



The maintenance requirements of the horse have 



