176 PRINCIPLES OF POULTRY FEEDING 



Growth and Maintenance. Owing to the increase in weight 

 which is taking place, the requirements of the growing animal are 

 constantly changing. Larger birds require more nutrients per day 

 per bird. Whether the object is for growth, for maintenance 

 simply, or for production, the larger birds require more feed, but 

 much less in proportion to live weight. It must be borne in mind 

 that, while the classification of weights given in Table IV is conveni- 

 ent, the grouping is only tentative; for example, it should not be 

 presumed that a hen just under five pounds in weight must always 

 have a ration supplying nutrients exactly as outlined, or one just 

 above five pounds should have the other ration; there is a natural 

 blending, the point of division being flexible. 



Under normal conditions, about three-fourths as much nutri- 

 tive material is required in a ration to maintain a flock of hens 

 without production as to keep them in full laying condition. Main- 

 tenance varies at different seasons of the year; as, for example, the 

 energy necessary to keep a hen's body at the normal temperature 

 of 105 F. during the winter requires more feed than to maintain 

 the same temperature in summer. 



Egg Production. Mature birds in full laying condition require 

 rations which have a much higher protein and ash content than 

 those required for maintenance, the increase being approximately 

 100 per cent. The carbohydrates and fat are not required in 

 nearly the same increasing amounts, yet the producing bird re- 

 quires an increase in energy or fuel value of approximately 30 

 per cent over that for maintenance. 



Fattening. The exact requirements for a fowl during the 

 period of fattening have never been worked out. The best results 

 in practice have followed a slight reduction in protein content 

 and an increase of about 75 to 100 per cent of carbohydrates 

 and fat as compared to egg production requirements. During 

 the finishing process a nutritive ratio of about 1 to 8 can be 

 freely fed. 



Practicability of Feeding Standards. One great need in study- 

 ing nutrition is reliable and actual scientific data pertaining to the 

 digestibility of feeding stuffs when fed to poultry. Volumes of 

 carefully collected data pertaining to digestion in other farm 

 animals have been published, but birds as a class have received 

 very little consideration. Owing to this lack of correct informa- 

 tion it is necessary to use the rules which are supposed to apply 

 to animals in common in figuring poultry rations. It is probable 



