308 POULTRY PRODUCTION 



The principal ash elements required in poultry feeding, 

 aside from oxygen, are calcium, phosphorus, sodium, potas- 

 sium, silicon, sulphur and iron. Calcium and sodium salts 

 are essential for muscular contraction. Calcium as a car- 

 bonate forms nearly the entire shell, or 11.4 per cent, of the 

 new-laid egg. The chief ash constituent of the contents of the 

 egg is sodium chloride, or common salt. In combination with 

 phosphorus, calcium forms bone. Phosphorus is found in the 

 egg, where it forms 0.27 per cent, of the edible portion. 

 Sulphur and iron, which are essential constituents of the 

 proteins of the body, are also found in the egg. Silicon is 

 found largely in the feathers. 



In the ordinary farm feeds, enough of all the ash elements 

 will ordinarily be furnished with the exception of lime, which 

 should be furnished in the form of calcium carbonate (oyster 

 shell) for laying hens and calcium phosphate (granulated 

 bone) for growing stock. 



Protein. — The term protein, or more properly crude protein, 

 designates the group of compounds found, both in the feed- 

 stuffs and the fowl's body and egg, which contain nitrogen. 

 These compounds are often referred to as nitrogenous sub- 

 stances, because the constant presence of nitrogen is their 

 most distinguishing characteristic. 



Among the more common compounds found in protein 

 are giycocoll, lysin, argenine, histidin, cystin, and trypto- 

 phan, known as amino acids. Not all of these groups have 

 the same feeding value. Nor does protein always contain 

 all of these groups. Giycocoll, an essential constituent of the 

 protein of feathers, is found in the protein of the seeds of 

 sunflower and hemp, but is not found in the casein of milk. 

 Milk casein also carries but a trace of cystin, which is a 

 sulphur-bearing amino acid. Commercial meat scrap, on the 

 other hand, is well supplied with cystin. Experiments in 

 progress at the Kansas Station indicate that possibly the 

 lack of cystin in casein is a limiting factor, when casein is 

 used as the main source of protein in the laying ration. 



It is be!cause of the fact that nitrogen is an absolute 

 essential to animal life that the nitrogenous compounds are 



