The Bulletin. 11 



THE CHEMISTRY OF FEEDS. 



In the chemical analysis of feeds the following determinations are 

 made : protein, fat, fiber, nitrogen-free extract, moisture and ash. 

 Without going into a detailed description of the chemical properties 

 of these classes of substances, the following general discussion will 

 be found valuable in interpreting the analysis of commercial feeds : 



PROTEIN. 



The term protein or crude protein as used in feed analysis includes 

 all the nitrogenous compounds contained in the feed. These com- 

 pounds are divided, chemically, into two classes — the true proteins 

 and the amido compounds. Familiar examples of the true proteins 

 are the white of egg, lean meat and the gluten of Hour. In seeds 

 and cereal products the amido compounds are present in very small 

 amount, and hence all the nitrogen is regarded as present in the form 

 of protein. The protein compounds contain, approximately, 16 per 

 cent of nitrogen, so to determine the amount of protein in a feed the 

 total amount of nitrogen is determined, and this, multiplied by the 

 factor 6.25, gives the amount of protein. 



The protein compounds are of very great importance in feeds, for 

 it is from them that the animal derives the nitrogenous materials 

 from which its muscular tissues are built. 



FATS. 



Fats, or more properly termed ether extract, include all the sub- 

 stances soluble in dry ether. These substances include the pure fats, 

 such as cotton-seed oil, linseed oil, etc., and the waxes, resins, 

 ehlorophyl, etc. In most feeds the waxes and resins are present in 

 such small amount that the entire ether extract may be regarded as 

 fat. In a few feeds, such as alfalfa products, the ether extracts the 

 ehlorophyl or green coloring matter of the plants. This amounts to 



onlv a small per cent. 



CRUDE FIBER. 



The term crude fiber includes the woody parts or the structural 

 materials of plants. It is composed largely of cellulose and is the 

 most indigestible part of the feed. As a rule, a feed with a high 

 percentage of fiber is considered to be a low-grade feed. 



MOISTURE. 



Water is presenl to some extent in all classes of feed. Hays 

 and commercial feeds usually contain from (i to L5 per cent of water. 



ASH. 



Ash is the inorganic or mineral matter of plant-. It is composed 

 principally of soda, potash, lime and magnesia, combined in the form 



