New York Agricultural Experiment Station. 59 



comments. 



While these experiments show that there is often an advantage 

 in feeding inorganic phosphates, even from such unusual material 

 as ground rock, with rations containing sometimes more than the 

 average amount of mineral matter, they are not quoted as recom- 

 mending the general use of bone ash and Florida rock for feeding. 

 Their chief value is in helping to better plan and interpret other 

 experiments. Fine raw or cooked bone is better material for sup- 

 plying a lack of phosphorus and lime, and more profitable to use, 

 in part because of the associated organic matter. 



The mixing of finely ground oyster shell in the food of chicks 

 except in very small quantity has always resulted in an unthrifty 

 condition and sometimes disease and death. At other times the 

 use of a small amount of coarser material has not appeared in- 

 jurious and it seems sometimes of benefit. It seems probable that 

 injury comes from too rapid or too nearly complete neutraliza- 

 tion of necessary acids in some digestive fluids. 



The fact that the mixing of sand in the food proved an advan- 

 tage, even for chicks running all day over sand, emphasizes the 

 importance of looking after the supply of grit. But it is not profit- 

 able to buy poultry foods in which sand has been mixed. Sand or 

 other grit can be obtained more cheaply. 



