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 ecpnomical 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. 

 12 



