Yes this is the bibliography. it's just a fascinating read. I agree not all the cites are pro Granite grit. but taken as a whole ,when the whole bibliography is read ,granite grit comes out the best choice among all the alternatives.
Best ,
Karen
Yes they're going to select the best of what is available .the best that is best for them is insoluble sharp-edged grit. Granite is the best selection there. Granite grit for poultry began because the poultry farmers in the 1930s clamored for it . they realized that when they fed sharp-edged...
No Sand will not do, its too small. it will pass right through the chicken .oyster shell has too much calcium in it, that will not do . plain stones from the yard aren't sharp enough, they won't do . You need insoluable granite grit which will have sharp edges.
best go to the store and buy some...