Constructive Material Required for the Body 387 



laying season, for the resulting products call for an 

 uninterrupted supply of food and the transformation 

 of all material that is available. Chickens of two 

 pounds weight at ten weeks of age show a gain over 

 the weight of the first week of nearly 1,700 per cent. 

 Ducklings five pounds in weight at nine weeks show a 

 gain during about eight weeks of 3,900 per cent. Such 

 rates of growth are not very unusual for young fowls 

 under favorable conditions. 



CONSTITUENTS OP THE BODY 



Whether the production of meat or of eggs is the 

 prime object, the young fowl must first be grown. 

 It is desirable, then, to consider what constituents make 

 up the body of the animal, for all must be derived 

 from the food. Many slight variations in composition 

 exist, of course, but there is always a certain approxi- 

 mation to the normal full-grown animal. 



In the whole body of the common fowl, unless espe- 

 cially fattened, not far from one -half of the dry matter 

 is protein and about 8 per cent ash. This of itself 

 would suggest that a slow growth must follow the use 

 of foods containing small amounts of nitrogenous and 

 mineral matter. 



Analyses made, mostly by Jenter, at the New York 

 Experiment Station, give as the average composition 

 of the body of a Leghorn hen, typical of the laying 

 breeds, 55.8 per cent of water, 21.6 per cen-t of protein, 

 3.8 per cent of ash, and 17 per cent of fat. This is 

 not the composition of the edible portion alone nor of 



