234 COMMERCIAL POULTRY RAISING 



by grit and oyster shells. No pen of poultry should be without 

 these two products. 



Oyster shells, also other kinds of sea shells, crushed to small 

 particles, are rich in carbonate of lime, so necessary for the forma- 

 tion of egg shells. They are quickly dissolved by the action of 

 the gizzard, hence they will not answer the purpose of grit. 



Grit, to aid the gizzard in grinding solids, corresponds to teeth 

 in other animals, consequently it must be hard, sharp and angu- 

 lar, and preferably bright, so that fowls will be attracted to it. 

 The commercial forms of poultry grit are usually made from 

 crushed quartz, granite, phosphate rock and feldspar. They 

 come in various sizes for poultry of all ages; 



Table XXIII. — Composition of Oyster Shslls 



Per Cent 



Carbonate of lime 93-71 



Carbonate of magnesia 1.39 



Phosphate of lime 0.76 



Organic matter 4.24 



Grit contains very little lime, and very little of the other min- 

 eral substances in soluble form. What nutrients it may supply 

 are but incidental ; its chief function is a mechanical one— grinding. 



Grit and oyster shells should be kept before fowls in separate 

 hoppers at all times. It is surprising the quantities they will 

 consume. If fowls have been deprived of grit for a considerable 

 period, they will eat it as ravenously as though it were grain. 

 Lack of grit, especially among flocks kept away from the soil, 

 has had much to do with the failures in the poultry industry. 

 Apparently, the soil furnishes some material which the system 

 of the fowl craves, and which is deficient in most of our foods. 

 Witness how hens revel in scratching in free earth. 



