124 Report oF THE DEPARTMENT OF ANIMAL HUSBANDRY. 
considered constituents satisfactory may be inferior because of a 
lack of mineral matter, probably phosphates. 
Not enough data are now available to show to just what ex- 
tent the deficiency of hme in the food for the younger chicks may 
have been responsible for inferior results. With laying hens, lack 
of lime could not have affected the results considered; for oyster 
shells were freely supplied, and it has been shown (see Bulletin 
No. 38) that such material can make good the frequent deficiency 
of lime. | 
It appears also that, while a cheaper vegetable food ration can 
sometimes be made to equal or surpass in efficiency a ration con- 
taining animal food by supplementing it with suitable mineral 
matter, there are plain limitations to its economical use. For lay- 
ing hens some animal food appears necessary for continued good 
results. Ducklings without an abundant supply of animal protein 
in the ration, together with a liberal proportion of mineral matter, 
seem unable to make any approximation to their normally rapid 
and most profitable growth. 
Although bone ash was used to make good an assumed defi- 
ciency in one ration and proved an efficient addition for the pur- 
pose, it should not be inferred that its purchase for feeding is to 
be generally recommended. It was necessarily used to obtain in- 
formation. Bone ash in the market is expensive. The same 
amount of mineral matter can be obtained much cheaper in fresh 
bone or animal meal, of which foods it constitutes an important 
part. In some instances, of course, dry bones, where no facili- 
ties exist for grinding, or green bones in questionable condition, 
ean be safely and economically used when charred or reduced to 
ash. The very desirable organic matter associated with fresh or 
cooked bones should not be wasted. 
