COMMERCIAL FEEDING-STUFFS 243 



by-product feeding-stuffs may be classified according 

 to their origin. Their sources are mainly as follows: 



1. The milling of wheat and other grains. 



2. The manufacture of oatmeal and a variety of 



breakfast foods. 



3. The manufacture of beer and other alcoholic drinks. 



4. The manufacture of starch and sugars, chiefly 



from corn. 



5. The manufacture of beet-sugar. 



6. The extraction of oils, chiefly linseed oil and cotton- 



seed oil. 



7. Screenings from the milling of wheat, and other 



refuses. 



8. Compounded feed^ made up from a variety of 



by-products. 



331. Wheat offals. — 'No commercial feeding-stuffs are 

 regarded with greater favor, or are more widelj)' and 

 largely purchased by American feeders than the by- 

 products from milling wheat. Wheat bran and mid- 

 dlings are cattle foods of standard excellence, whether 

 we consider composition, palatableness, or their relation 

 to the quality of dairy products. These feeding-stuffs 

 consist of particular parts of the wheat kernel, a knowl- 

 edge of the structure of which aids greatly in under- 

 standing what they are and why they possess certain 

 chemical and physical properties. 



332. Structure of the v^heat grain. — ^To ordinary 

 observation the wheat grain appears to be merely a 

 seed, but it is really a seed contained in a tightly-fitting 

 seed pod. This pod, which is woody and tough, con- 

 stitutes the outer coating of the kernel. On the seed 

 itself are two more hard and resisting coatings, one of 

 which is double, that serve to protect the softer parts. 



