SECTION VIII. 



COMPOSITION OF FARM ANIMALS. 



In the preceding pages we have become familiar with the 

 compounds that are contained in feed stuffs and animal bodies. 

 We learned that the plant substances are changed to form body 

 tissue, bones, blood, etc. by the animal. Let us now consider the 

 animal body composition, or the proportions of the compounds 

 in the animal body, to find out the food requirements, the differ- 

 ences in young and mature animals, lean and fat animals, species, 

 increase and nature of increase during growth and fattening, 

 and the relation of the ingredients of plants to the stored up 

 materials of the animal. 



We know that the compounds of plants and animals are: 



Compounds of plants Compounds of animals 



Protein Protein 



Fat (ether extract) Fat 



Nitrogeii free extract Water 



Crude fiber Ash (mineral matter) 



Water 



Ash (mineral matter) 



Or we may express animal body composition as: 



L 



1 Organic matter 



Ani-l {S^ymatter ^^^^ 



Protein 



Fats 



Dry Matter. — It is evident that there are many compounds 

 somewhat similar in plant and animal life, but there is a great 

 difference in the proportions of the compounds in the plant and 

 the animal. The dry matter of plants is made up principally of 

 carbohydrates and crude fiber, but in the animal carbohydrates 

 are present in such small amounts as to be disregarded in stat- 

 ing animal body composition and crude fiber is not found in the 

 animal body. The dry matter of the animal body is mostly fats. 

 The percentages of fats and protein in animals are much greater 

 than in most plant substances. 



Composition of Farm Animals. — The most valuable experiments 

 that have been conducted on animal body composition are those 



