360 POULTRY PRODUCTION 



their nutritive effect as well, the feeder may compute a 

 balanced ration/ 



There are two methods of calculating a feeding standard. 

 One is by means of digestion trials and the other by dietary 

 trials. Theoretically, the proper method is by means of 

 digestion experiments. While this is possible for maintenance 

 standards, it is not practicable for a standard for hens in 

 full laying or for growing young stock. This is because the 

 ijecessary technique employed in carrying on digestion experi- 

 ments would greatly interfere with egg production or growth 

 and so would defeat their purpose. 



' The method using dietary trials is the one to which poultry 

 feeders must look for the present. By this method the effi- 

 ciency of different rations for a given purpose is compared 

 arid thte amounts and proportions of the digestible nutrients 

 in the most efficient rations may then be taken as a standard. 



The most complete standards to be had at present are 

 those compiled by W. P. Wheeler at the New York Experi- 

 ment Station. Unfortunately in the absence of specific 

 data for poultry his calculations were of necessity based on 

 coefficients of digestibility observed for other animals. These 

 are therefore only approximations to a true standard. It will 

 remain impossible to compile a true standard until very much 

 more work has been done upon the establishing of the diges- 

 tion coefficients of all the common poultry feeds, than has 

 been done up to the present time. In the meantime the 

 Wheeler standards will continue to be of great service in 

 pointing toward the rational feeding of poultry. 



Maintenance Standard. — A maintenance ration is one that 

 furnishes a sufficiency of each and all of the several nutrients, 

 but no more than is required to maintain a given bird that 

 is not laying and is as nearly at rest as possible, so that it will 

 not gain or lose in weight. 



Because of the pronounced vitality, the very rapid breath- 

 ing, the high body temperature, and the fact that the 

 smaller the animal the greater is the surface area relative to 

 bulk, and the greater the relative heat production, it might 

 be expected that poultry would demand a relatively high 

 consumption of carbohydrate. As a matter of fact, while 



