CHAPTER XX 

 THE EFFICIENCY OF RATIONS 



We have learned that a maintenance ration is one which 

 is just sufficient to support the vital functions of the animal 

 when it is at rest, without any loss or gain of body tissue. 

 If an excess of feed above the requirements for mainten- 

 ance is given the animal, there may be some production, i.e. 

 the animal may do work, or it may produce milk, or meat, 

 or wool, or some other product which has an economic 

 value. However, not all the excess feed above the main- 

 tenance requirement can be recovered by the animal in the 

 form of some useful product. As a matter of fact, a large 

 part of it is wasted by the animal in some form or other. 

 It already has been shown that the horse can recover in 

 the form of work only about one-third of the net energy of 

 the ration. Similarly, meat-producing and dairy animals 

 can recover only a fraction of their ration in the form of 

 meat or milk. 



The efficiency of a ration is its value expressed in terms 

 of the product for which the animal is fed. In other words, 

 the efficiency of a ration expresses the amount of feed re- 

 quired to produce a given result, such as a pound of gain, 

 or a pound of milk. The efficiency of the ration must not 

 be confused with the economy of the ration as expressed in 

 dollars and cents. As a matter of fact, the ration which 

 is most efficient is often uneconomical, owing to its high 

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