NUTRITION OF POULTRY 175 



Differences in beaks and crops. In the gallinaceous birds the 

 upper mandible forms a stout, sharp hook, and this beak is a most 

 efficient tool for the prehension of food and also to supplement 

 the claws in uncovering food concealed on or near the surface of 

 the ground. In waterfowl the bill is much larger : in the duck it 

 is long, broad and flat, shovel-like, and especially adapted to secur- 

 ing food in water ; the bill of the goose is less flattened, stronger, 

 and the edges of the upper mandible are more serrated. The 

 serrations of the mandibles in waterfowl seem to serve a double 

 purpose : they give a firmer hold on the coarse vegetation grow- 

 ing in water and in moist places, of which these birds eat great 

 quantities ; they also serve as strainers to retain in the mouth 

 small forms of animal life taken in with water, which is forced 

 out at the sides. The crops of gallinaceous birds are large and 

 will hold considerable quantities of food ; the crops of ducks and 

 geese are small. 



Natural foods and feeding habits of poultry. In a study of the 

 subject of feeding, the natural foods and feeding habits of poultry 

 must be considered. It is to these natural diets that the organs and 

 habits of the birds were adjusted in the wild state, and though they 

 readily adapt themselves to different diets, there are some features 

 of the natural life and diet which must be preserved in every arti- 

 ficial method intended for continuous use. The form in which food 

 is taken is of more importance in feeding practice than the proper 

 balancing of nutrients in the ration; for while a badly balanced ra- 

 tion produces malnutrition, its bad eifects develop slowly and are 

 usually promptly remedied by a proper diet, but a ration that is 

 unsuitable in form (however well balanced in its nutrient elements) 

 if eaten by the bird reluctantly and in insufficient quantities may 

 result in malnutrition, or, if eaten readily, may cause disorders of 

 the digestive organs which develop quickly and are not easily rem- 

 edied. The form in which food is taken also has an important 

 influence on exercise and the general physical habits which affect 

 digestion. 



Gallinaceous domestic birds ^ are cotispicuously granivorous 

 when compared with carnivorous and herbivorous creatures, but 

 under natural conditions, with opportunity to eat as much as they 



' Fowls, turkeys, guineas, peafowls, and pheasants. 



