THE CHEMICAL COMPOSITION OF FEEDINGSTUFFS 21 



contain phosphoric acid and some nitrogen-containing com- 

 pounds. They are found in the protoplasm of all cells. 

 They occur most abundantly in the brain, nerves, heart, 

 and blood corpuscles, in milk and eggs, and in the seeds of 

 all the cereals. Although little is definitely known of their 

 functions, yet they are among the most important substances 

 in living matter, being essential components of all living 

 cells. 



Fat in Feedingstuffs. — The quantity of fat in a feeding- 

 stuff usually is determined by extracting a finely ground, 

 dried, weighed sample of the feed with ether, which dis- 

 solves out the fat. The ether is then evaporated off and 

 the residue of fat is weighed. The weight of the fat divided 

 by the weight of the sample and multiplied by 100 gives 

 the per cent of fat. However, not only fats, but other sub- 

 stances, such as waxes, chlorophyll, and some of the organic 

 acids also, are extracted from the feedingstuff by the ether. 

 This is true especially in the case of roughages, such as hay, 

 fodder, and silage. Thus the extract is often spoken of 

 as crude fat, or ether extract. 



Of the feedingstuffs, the oily seeds, as flaxseed and cotton- 

 seed, and the waste animal products, as tankage and crack- 

 Hngs, contain the most fat, — 12 to 35 per cent. The oil 

 by-products contain a medium amount, — 3 to 13 per cent. 

 Of the ordinary grains, corn contains the largest amount, 

 — 5.0 per cent. Non-leguminous hays, straws, roots, and 

 the fresh pasture grasses contain the smallest amounts of 

 fat, — 0.1 to 3 per cent. 



The average percentages of fat or ether extract in the 

 various classes of the ordinary feedingstuffs are shown in 

 Table 6. 



