A GUIDE FOR KEEPERS OF POULTRY 163 
Other elements are necessary to nutrition, such as sul- 
phur, phosphorus, lime, salt, iron and other minerals. 
‘These are the inorganic residue which remains after burn- 
ing and are known as ash. Burn the body of a fowl and 
the little pile of ashes that remains will represent all the 
mineral matter contained in the body. All feed contains 
these mineral elements, and the feeder need not pay any 
attention to them, for if the feed is properly constituted 
as to protein, carbohydrates and fat it will almost al- 
ways contain sufficient of the mineral elements to supply 
all the needs of the fowl. It should be remembered, 
however, that these mineral elements are as important as 
the three to which so much attention is paid. When a 
hen is laying regularly her feed may be deficient in lime, 
because she requires a large quantity of this element in 
order that she may supply material for egg shells. In 
order to meet this demand we feed crushed oyster shells 
or crushed bone. Very often a flock of hens otherwise 
properly fed fails to lay as many eggs as it might be- 
cause of a deficiency in lime in the feed. For this reason 
poultrymen should always keep a supply of oyster shells 
or crushed bone where laying hens may have constant 
access to it. 
Protein is the most valuable and the most costly part 
of any ration. All protein-rich feeds are more costly than 
those which contain a relatively small quantity of this 
substance. A protein-rich ration is called a “nitrogen- 
ous” ration because nitrogen is a large component part 
of the elements grouped and denominated protein. Pro- 
tein is that material in feed which goes to make brain 
matter, nerve cells, vital organs, intestines, tendons, skin, 
feathers, beak, claws, skin and, in combination with lime, 
bones and muscle (lean meat). In short, it is largely the 
