CHAPTER V 



USES OF FEED BY ANIMALS— FEEDING 

 STANDARDS 



We have seen that the animals, through their various digestive 

 fluids, are able to dissolve certain feed components from the feeding 

 stuffs which they eat, and that these components are used for main- 

 taining the vital functions of the animals, and for the production of 

 ■work, meat, milk, wool, etc., in the case of different farm animals. 

 When only sufficient feed is supplied to maintain the body weight 

 of the animal, no production is possible, except in the case of milk- 

 producing animals. Even when the supply of feed is not sufficient 

 to prevent a loss of body weight, these animals 1 will continue to 

 produce milk, and the interests of their young are thus safeguarded. 

 But this is done at the expense of the flesh (or body fat) of the dam. 

 Good dairy cows may lose consdderable weight under these condi- 

 tions; this is especially apt to occur shortly after freshening, even 

 though a .rather liberal supply of feed may be given, and it is often 

 necessary to counteract this tendency to loss of flesh at this period 

 by supplying special fattening feeds. 



Maintenance Requirements. — The feed required for main- 

 taining an animal at an even body weight is known as a maintenance 

 ration. This supplies the energy necessary for the normal exercise 

 of body functions, like breathing, heart action and circulation of 

 blood, mastication of food and its movement through the digestive 

 tract, etc. A standing position as well as moving about also call for 

 some energy that must be supplied by the maintenance feed. 



The amounts of feed required for body maintenance have been 

 studied by a number of scientists since the middle of the last 

 century, and the maintenance requirements, of different classes of 

 farm animals are now definitely known. This subject has both a 

 theoretical and practical interest, and is of fundamental importance 

 in the study of the uses of feed by animals, since about 50 per cent 

 of the feed they eat is used for body maintenance. 



The earliest statements as to the maintenance requirements of 

 farm animals came to us from Germany. Wolff's maintenance stand- 

 ard for cattle, for instance, called for a supply in the feed of the 

 following digestible components: 0.7 pound protein, 8 pounds carbo- 

 hydrates, and 0.1 pound fat per 1000 pounds body weight and per 

 day. Later investigations by Sanborn, Caldwell, Haecker, and 

 others showed, however, that this is a larger allowance than neces- 

 sary. The Haecker maintenance standard for barren dry cows is 

 now generally accepted ; this calls for 0.7 pound protein, 7 pounds 

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