216 FEEDING 



Water, by circulating and filling up the tissues of the body, 

 distends it and makes it appear plump. Water also plays 

 an important part in regulating the body temperature. As- 

 similation, or the diffusion of feed materials through thin 

 walls, is greatly promoted by the water ingested. Water, 

 also, is the vehicle by which materials are conveyed 

 from one part of the body to another. These facts demon- 

 strate that some knowledge of the chemical composition 

 of the body is essential to an intelligent study of feed ma- 

 terials themselves. 



LABORATORY EXERCISES 



Exercise No. 56. — Composition of a Bird. — Kill a fat hen. 

 Cut her up into six or eight pieces by severing the wings, 

 legs and neck. Open the abdominal cavity and separate 

 some of the body fat. With the material thus afforded it 

 will be possible to show to the class portions of the body 

 containing each of the compounds which go to make it up. 

 Lean meat and feathers will illustrate essentially a nitrog- 

 enous product. The body fat may be closely examined as 

 to structure. The bones will serve as an example of ash or 

 mineral matter. If scales are available the pieces can be 

 weighed and then placed in a double boiler and heated for a 

 few hours, after which the flesh should be weighed again. 

 How can the loss of weight be accounted for? 



Exercise No. 57. — Composition of Feeds. — Feeds of the 

 different groups should be secured and can be used in 

 connection with the study of their composition. The differ- 

 ence between dry and green fodder can be illustrated by 

 mowing some grass on the school lawn and weighing it im- 

 mediately; then spread it out thin and allow the sun to dry 

 it for two days. When it is thoroughly dry, weigh it again. 

 How can the difference in weight bo accounted for? In 

 which condition do the poultry like the grass best, green or 

 dry? Why? 



