302 POULTRY PRODUCTION 



and Loew,' found that feeding liens with potato and l)arley 

 alone caused the shell of the egg to disa])pear. After about 

 three weeks laying stopjx^d, apparently due to the ash 

 deficiency in the ration. 



The principal ash elements required in poultry feeding, 

 aside from oxygen, are cah-ium, ])hosphorus, 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 i)er cent of the 

 new-laid egg. In combination with phosphorus, calcium is 

 an important constituent of bone. Phosphorus is found in 

 the eggs, where it forms 0.27 per cent of tlie edible ])ortion. 

 Sulpliur 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 tlie ash elements 

 \\\\\ ordinarily be furnished with the exception of calcium and 

 ])hos])horus, which should be furnished in the form of calcium 

 carbonate (oyster shell ) for laying hens and calcium phosphate 

 (granulatetl bone) for growing stock. Lewis'- four.d that an 

 organic source of phosi)horic acid such as animal bone was 

 much more elhcient than an inorganic one such as jjhosphate 

 rock. 



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

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

 stufl's 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. 



There are thousands of dift'erent proteins all of which may 

 be dec(jniposed into eighteen or twenty amino-acids. Among 

 these are glycocoU, lysin, argenine, histidin, cystin and 

 tryptophan. Certain amino-acids can be built up by the 

 body while others cannot. GlycocoU, an essential consti- 

 tuent of feathers may be built up by the body while tripto- 

 phan, cystin and lysin cannot. Alilk casein carries but a 

 trace of cystin, which is a sul]jhur-bearing amino-acid. 



'Deutsche Revue, July, 1912. 

 2 New Jersey Bulletin, No 2G5. 



