PRACTICABILITY OF FEEDING STANDARDS 177 
that the accepted laws of nutrition observed with other animals 
hold true to only a limited extent in regard to poultry, but they 
form the best guide until more accurate data can be obtained. 
Birds have a type of digestive system entirely different from that 
of any other group of animals, are of a much more active disposi- 
tion, and of a much higher body temperature, so that it is 
only reasonable to suppose that the same coefficients of digestion 
and the same energy values would not in all cases apply. The 
standards here given are as practical and reliable as are at present 
obtainable. | 
Digestion experiments have been carried on with poultry at 
the Maine Station with certain definite results. Corn showed a 
higher digestibility than any other grain tested. Wheat bran when 
fed to adult birds showed a rather low digestibility. A mixture 
of finely cut clover and corn meal was a more economical feed than 
bran. It was found that any great proportion of crude fibre was 
undesirable, being but slightly digested and of little value other 
than giving bulk to the ration; and that the addition of about 
seven per cent of bone ash slightly increased the digestion coeffi- 
cient of a mixture containing vegetable matter. 
Considerable experimental work has been done by the United 
States Department of Agriculture pertaining to the digestibility 
of poultry rations. The results of the work show that corn in the 
ration is one of the most economical sources of crude protein, 
nitrogen-free extract, and fat, because corn is highly digestible. 
Oats and wheat should be utilized for their crude protein and fat. 
Where wheat is used extensively, adequate provision must be 
made for the deficiency of fat in this grain. It was found that 
protein and fat in beef show high coefficients of digestibility, the 
protein considerably higher and the fat but slightly lower than the 
corresponding nutrients in corn. 
Until recently, all feeding determinations have been based on 
standards and coefficients of digestibility derived from German 
sources. When these standards are used, the total nutrients in 
the ration are considered, and the requirements of the individual 
animal determine the exact feed stuffs and the proportion in which 
they should be.combined. It must be remembered that no stand- 
ard, however derived, can be properly used as the basis of absolute, 
inflexible rules. They can be used as the starting point for the 
feeder, more especially the beginner, and are not supposed to 
eliminate the use of judgment. 
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