CHAPTER X 

 FEEDING STANDARDS 



We have traced in the preceding chapter the processes of solu- 

 tion and the destination of the various nutrients of feeding ma- 

 terials. It will now be necessary to consider briefly the develop- 

 ment of our knowledge leading to the establishment of feeding 

 standards and the present status of such information. In 1810 

 Thaer, in Germany, formulated the first standard, publishing a 

 table of hay equivalents, using meadow hay as the standard. It 

 had little experimental foundation and soon fell into disuse. In 

 1859 Grouven published the first standard based upon the quan- 

 tity of proximate constituents in feeding materials. 



The work of Liebig, Boussingault, and others, with the new 

 tools of a rapidly developing chemistry, was paving the way for 

 standards based on chemical analysis. But the tables of Grouven 

 did not meet the requirements, since they were -based on the total, 

 instead of the digestible nutrients. 



In 1864 the feeding standards of Wolff, the eminent German 

 scientist, first appeared. They are based upon the amounts of 

 digestible protein, carbohydrates and fats, required by the va- 

 rious classes of farm animals. These standards have been pub- 

 lished annually in the Mentzel-Lengerke calendar down to 1896 ; 

 for the next ten years they were issued by Lehmann of the Berlin 

 Agricultural High School, and since 1907 by Kellner, modified 

 to a starch equivalent basis, to be described later. The Wolff 

 standards have seen wide use by practical stockmen because of 

 their simplicity and definiteness. 



Co-efficient of digestibility. The nutrients of feeds are not 

 wholly digestible. A part passes through the animal without 

 having been dissolved by the digestive juices and thereby made 

 available to the animal. The general method of measuring the 

 digestibility of feeds has been to supply the animal with 





