THE MAINTENANCE RATIONS OF FARM ANIMALS. 



INTRODUCTION. 



Feed is supplied to farm animals in order that they may either 

 yield products useful to man as materials for human food and cloth- 

 ing or serve him by the performance of mechanical work. But 

 as a factory must first be supplied with enough power to keep in 

 motion the shafting, belting, and other machinery before any product 

 can be turned out, so the animal mechanism must be provided with 

 sufficient feed to maintain the processes essential to life before any 

 continued production is possible. The amount of feed required for 

 this purpose is called the maintenance ration of the particular animal. 

 It is the quantity of feed necessary simply to support the animal 

 when doing no work and yielding no material product. If an animal 

 receiving exactly a maintenance ration were subjected to a so-called 

 balance experiment, there would be found an exact equality between 

 income and outgo of ash, nitrogen, carbon, hydrogen, and energy, 

 showing that the body was neither gaining nor losing protein, fat, 

 carbohydrates, or ash. 



The word " maintenance " is sometimes used popularly in another 

 sense to signify the total amount of feed required, for example, by a 

 horse in order to perform his daily work or by a calf in order to make 

 a normal growth. It is important to grasp the idea that, in its 

 technical sense, the maintenance requirement means the minimum 

 required simply to sustain life. The feed of the horse or calf would, 

 from this point of view, be regarded as consisting of two portions; 

 one of these is the maintenance ration, which if fed by itself would 

 just support the horse at rest or the calf without growth, and the 

 other the productive portion of the ration by means of which work 

 is done or growth made. To recur to the illustration of the factory, 

 the maintenance ration keeps the empty machinery running, while 

 the additional feed furnishes the power necessary to turn out the 

 product. 



It might seem at first thought that not much importance attaches 

 to a study of the maintenance ration. The animal kept on such 

 a ration yields no direct economic return and hence simple main- 

 tenance feeding should be avoided, so far as practicable, and when 



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