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 
