CHAPTER IV 

 USES OF FEED BY ANIMALS 



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 will con- 

 tinue 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 mother. Good milch cows with highly-developed dairy 

 qualities will lose considerable weight under these conditions; this 

 is especially apt to occur shortly after freshening, although 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 amounts of feed required 

 to maintain farm animals at an even body weight 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 fol- 

 lowing 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 

 digestible carbohydrates, and 0.1 pound digestible fat per 1000 

 pounds body weight. 



Of late years the amount of chemical energy which different 

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