204 POULTRY CULTURE 



elements that they require,^ and that adult birds get all that they need 

 except for the formation of eggshells when they are laying heavily. 



Dry bone. Granulated or finely broken dry bone and bone meal 

 are the commercial forms in which bones are supplied for poultry 

 feeding. Left to themselves, poultry will not injure themselves with 

 bone in any form unless the ration they have been receiving has 

 been very deficient in mineral elements. Bone meal is usually given 

 in the mash and is a frequent cause of trouble. It should be used 

 only occasionally and always in very small quantities. 



Oyster shells. Crushed or ground oyster shells are the most 

 popular shell food for laying hens. As a rule young stock do not 

 care for ground shell. If they are forced to eat it, no injury may 

 follow, but neither will there be any apparent benefit. The need of 

 material for eggshells and the value of oyster and similar shells for 

 this purpose may be easily and quickly demonstrated in practice. 

 When shell supplies have been insufficient, the beneficial effects 

 of feeding shell will appear within two or three days. 



Digestible minerals. The digestible minerals are principally in 

 the form of grits, the chief value of which is in the soluble mineral 

 elements, that either contribute directly to nutrition or assist chemi- 

 cally some vital process. When fed with indigestible grits, hens 

 whose ration lacked mineral elements have frequently been known 

 to consume and void very large quantities of grit daily .^ 



' How far these are derived from other foods and how far from minerals picked 

 up on the range is a question for investigation. The question of grit, whether 

 for grinding or as a supply of mineral elements required in nutrition, is much more 

 easily disposed of in practice than in theory. Poultry keepers in practice gener- 

 ally leave it to the poultry. Grit is cheap, and, keeping a supply of it before the 

 birds, they know that if the birds need it, they have it. That disposes of the ques- 

 tion in practice but does not affect its merits. I followed the common practice 

 long after I was convinced in my own mind that the birds had no need of grit to 

 grind their food, but finally abandoned it, and since about 1902 have given no grit 

 to poultry except coarse gravel in the first feeds of young ducks and geese. The 

 function of this appears to be mechanical and to relate as much to the operation 

 of the crop as to the operation of the gizzard. This is sometimes apparent, also, in 

 feeding adults fowls and ducks. The beneficial effects of coarse material are sometimes 

 seen immediately on feeding that material, and long before it reaches the gizzard. 



" In two such cases reported to me, consumption was at the rate of over a 

 quart per day for twelve medium-sized hens. A pen of twenty-five extra large hens 

 in my yards, supplied with indigestible grit and oyster shell, consumed in eight 

 months less than a pint of the grit, but frequently ate a quart of shell a week, 

 the consumption varying regularly according to egg production. 



