POULTRY FEEDS AND FEEDING 



after being digested, changed and regulated by these 

 various organs, passes into the blood directly from the in- 

 testines and is circulated and used to repair waste and 

 rebuild tissue throughout the body. These blood veins 

 cover the intestines and thus draw their nourishment di- 

 rectly from the intestines. The nitrogen is probably ex- 

 creted almost entirely through the kidneys as urine. 

 Water is given off both through the urine and through the 

 lungs. Carbon is eliminated largely by oxidation in the 

 lungs as carbon dioxide. The droppings consist of indi- 

 gestible food nutrients which pass out through the body. 

 The bile is a secretion of the liver which does not contain 

 any ferments or have any direct digestive action, but co- 

 operates with the pancreatic juices in the digestion of food 

 by providing the proper medium and necessary conditions. 



STRUCTURE OF THE EGG 



An egg consists of about 57 per cent albumen, 33 per 

 cent yolk, and 10 per cent shell. The yolk is supported 

 near the center of the egg in dense albumen which is sur- 

 rounded by a layer of finer or more liquid albumen. All 

 of this is enclosed in two thin membranes commonly re- 

 ferred to as the skin of the egg which lie directly under 

 the egg shell. These membranes separate at the large end 

 of the egg and form a small air cell, which increases in 

 size with the age of the egg. The egg shell is a hard 

 substance consisting largely of lime. The size of the eggs 

 from different breeds and from different strains of the 

 same breed varies considerably. It is not influenced by 



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