272 POULTRY CULTURE 



with secretion and excretion. They direct metaboUsm of the 

 body, though how is Uttle understood. They regulate the 

 fluid flow from blood to tissues and vice versa. Irritabihty 

 of muscle and nerve is due to salts. 



Young growing birds require more salts than adults. The 

 activity of enzymes, whose function in building up and tearing 

 down chemical compounds in the animal body requires certain 

 degrees of acidity and alkaUnity, which is maintained in proper 

 degree through the presence of mineral salts. Animals can 

 live but a short time on feeds free from mineral salts. 



Salts assist in the formation of secretions, repair, and dis- 

 integration. The growth of solid tissue depends on the inor- 

 ganic material supphed by the blood. One of the important 

 functions of the salts in the blood is to maintain the vitahty 

 of the tissues. This is one of the principal functions of sodium 

 chloride. 



The excess of mineral bases in the food must be maintained 

 at a high level. 



Wheat and other seeds are deficient in calcium, sodium 

 and chlorine. 



Essential Food Nutrients. — The properly balanced feed 

 mixture must have the proper kinds and quantities of amino 

 acids in the protein, the proper kinds and quantities of mineral 

 matter, and feed stuffs readily digestible and assimilable. 

 There must also be the proper amount of fat soluble vitamine or 

 food hormone. 



A food hormone is an essential element or life-giving sub- 

 stance essential for maintenance of life and for pi'oper growth 

 of the bird. There are two kinds of hormones : first, a water 

 soluble hormone found in abundance in all feed stuffs, and 

 second, a fat soluble hormone found only in the fat of eggs, the 

 fat of milk, certain parenchymatous glands as the hver and 

 kidneys, and to a degree in the leaves of plants. It is not 

 found in muscle structure. An animal will not grow on seeds 

 alone. The fat soluble hormone is not found in the vegetable 

 oils. Birds without the fat soluble vitamine will die in about 

 two weeks. The symptoms are at first swelKng of the eyes 

 and eyehds, and the eye balls may burst. Feeding the bird 

 egg yolk or butter-fat will reheve this condition. If the water 



