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, an 

 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 Ratio. 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. 



