114 THE SCIENTIFIC FEEDING OF ANIMALS 



these meals are digested better if fed in the dry state. For pigs these 

 materials are usually scalded or boiled before feeding. 



The most important by-products of oil manufacture are the follow- 

 ing: 



Linseed by-products. — From the seeds of common flax, Linum usita- 

 tissium. This has the advantage over other oil by-products in that it 

 swells in water and forms a larger amount of gelatinous material which 

 is so important from a dietetic point of view. If the seeds have been 

 steamed this property is destroyed. 



Linseed cake, which is put on the market in the form of round slabs, 

 has a dirty greenish brown color and a characteristic linseed odor. It 

 contains from 30 to 33 per cent of crude protein, of which 27 per cent 

 is digestible albumen; 8 per cent fat, and a starch value of 72 per cent. 

 The linseed meals which have a more dark-green color contain 35 per 

 cent crude protein, of which 31 per cent is digestible albumen; 3 to 4 

 per cent of fat, and a starch value of 65 per cent. Both forms are nearly 

 free from starch. If the iodin test produces a pronounced reaction it 

 points to adulteration with starchy matter (weed seeds, etc.). 



Linseed by-products are frequently contaminated with all kinds of 

 seeds and earth particles, and owing to their high price, are frequently 

 adulterated with screenings, charlock, dodder, hempseed or with other 

 oil cake of inferior value or quality, like rape, poppy, castor bean, mus- 

 tard, etc., or hulls of peanuts, cottonseed, cocoanut shells, spoiled feed 

 meals made from the grains, mineral matter, etc. These adulterations 

 of course affect their chemical composition, their dietetic value and even 

 their wholesomeness. In a case reported by Dahl linseed cake contained 

 2 per cent of carbonate of lead and caused the death or required the 

 slaughter of 10 cows and a calf. Mere ocular inspection is not sufficient 

 to detect these adulterants. For particulars see the chapter on the de- 

 tection of adulterants. 



The linseed by-products are fed chiefly as dietetic substances to ani- 

 mals that are in a weak or run-down condition and to young stock dur- 

 ing the weaning period. They are usually too expensive to be used as 

 a regular part of the rations for milk-producing, fattening or working 

 animals. If given in small amounts, 1 pound per day, they constitute 

 an excellent feed for milk cows. Quantities in excess of 2 to 4 pounds 

 daily for milk or fattening cattle should, however, be avoided, on ac- 

 count of the unfavorable effect of large rations on the quality of the 

 milk and meat products. Linseed by-products are usually fed ground 

 and wet or made into gruels or broths. 



Rapeseed and turnip-seed cake. — The seeds of Brassica napus and B. 

 rapa. Rape seeds have a dark brown color, turnip seeds a brown color 

 and not as smooth a surface as the former. Rape cake has a strong, 

 onionlike, pleasant odor, and a greenish yellow color which becomes more 

 grayish yellow with age. That which has been subjected to the action 



