14 COMMERCIAL FEEDING STUFFS. 



abundant quantities in the cheaper, coarse feeds, it is usual to value 

 the more concentrated and higher priced feeds entirely on their pro- 

 tein and fat content. That this does not always give a correct valu- 

 ation will be shown later. 



Protein is of primary importance, as it serves to build up new tissue 

 and replace the broken down cells destroyed in the katabolism of the 

 body. Under certain circumstances, as in starvation, the protein 

 may serve as a source of heat and energy. 



Fats are of use principally as sources of heat and energy, being 

 usually reckoned as two and one-fourth times as valuable in this 

 respect as the carbohydrates. They also protect the protein com- 

 pounds of the body against destruction and serve as a packing and 

 protection for the other tissues. 



The carbohydrates are also of importance as sources of heat and 

 energy. The members of this group differ, however, from one another 

 in their nutritive value, since their digestibility varies widely. The 

 starches and sugars are easily and almost completely digested, while, 

 the crude fiber, pentosans, and other less well-known substances are 

 digested with much more difficulty and less completely: It is, there- 

 fore, evidently desirable that starches and sugars should constitute 

 the principal part of the carbohydrates in a feeding stuff, especially 

 in a concentrated feeding stuff. The less valuable carbohydrates, 

 such as pentosans and crude fiber, the presence of which is necessary 

 to give body to the feed, can be supplied by the cheaper coarse fod- 

 ders. It becomes evident, therefore, that if two concentrated feeds 

 contain the same amounts of protein, fat, and carbohydrates, but in 

 one the carbohydrates consist principally of woody hulls, while in 

 the other they consist principally of starches and sugars, the latter 

 is to be preferred. 



DISCUSSION OF RESULTS OF ANALYSES. 



Table 1 gives the names of the various cattle foods examined, 

 together with the name and address of the manufacturer. The results 

 of the chemical and microscopical examinations are given in the 

 various tables arranged in groups (cottonseed, linseed, etc.) in con- 

 nection with the discussion of the data. Where more than one sam- 

 ple of a certain product was examined the individual as well as an 

 average analysis is given. As manufacturers, and in fact the gen- 

 eral public, interpret the words bran, middlings, and red-dog flour 

 so differently, the microscopical results of wheat products are not 

 reported under these names, but are recorded as wheat products 

 Nos. 1, 2, and 3. The significance of these numbers and the dis- 

 cussion of the histological features of the various constituents are 

 given under ."Microscopical examination/' page 74. 



