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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