208 PRACTICE OF POULTRY FEEDING 
is usually expressed in the latter form. Two features must be 
considered in this respect: (1) The amount of each of the three 
nutrients—protein, carbohydrates, and fat—that 100 pounds live 
weight will require; and (2) the heat or energy which the ration 
will develop when consumed. 
As stated in a previous chapter, standards have been devised 
that give approximately the amounts of different nutrients and 
the number of heat units required. Wheeler’s standard shows 
digestible nutrients per day for 100 pounds live weight for hens 
in full laying condition. By this standard it will be noted that 
as birds increase in size the amount of feed required by the indi- 
vidual is increased per individual, but actually decreased for each 
100 pounds live weight. This is due to the fact that fewer in- 
dividuals are required to make the 100 pounds weight. Feeders 
often fail to supply enough nutrients for heavy layers. 
Nutrients must be in the Right Proportion.—It is just as essential 
that the nutrients in the ration be of the right proportion as that 
they should be sufficient in amount. The right proportion will be 
determined by the purpose of feeding and by the age and character 
of the individuals themselves. For instance, if the purpose is to 
feed for fat and flesh, as in the preparation of birds for market, ari 
increased proportion of fat and carbohydrates in the feed will be 
required. On the other hand, if the feeding is for egg production, 
a large amount of protein material will be essential. 
The age and the breed of the specimens being fed influence 
the proportion of nutrients in the following manner: The heavier 
breeds naturally have a tendency to take on flesh quickly, and, 
therefore, large proportions of fat-forming nutrients are not re- 
quired when feeding for egg production. With more active breeds, 
as the Leghorns, more of such nutrients may be used. As the indi- 
vidual gets older the natural tendency becomes more and more 
pronounced to take on excessive flesh, and this character of feed 
should be withheld. 
Nutritive Ratto—The proportion of nutrients in any ration is 
called the “ nutritive ratio.’ By nutritive ratio is therefore meant 
the relative value of the particular nutrients, expressed arbitrarily 
in terms of each other. The ratio is expressed in numbers giving 
the protein as one and comparing this with the combined carbo- 
hydrates and fat. For instance, a ration containing 100 pounds 
of protein and 400 pounds of carbohydrates and fat will be ex- 
pressed as having a nutritive ration of one to four. 
