690 NUTRITION OF FARM ANIMALS 



contained in rations for various purposes in order to secure 

 satisfactory results under average conditions. Thus, the 

 Wolff standard for dairy cows was : 



FEEDING STANDARD FOR MILK Cows PER DAY AND 1000 POUNDS LIVE 



WEIGHT 



Total dry matter 24 pounds 



Digestible protein 2.4 pounds 



Digestible fat 0.4 pound 



Digestible carbohydrates 12.5 pounds 



Nutritive ratio i : 5.4 



This means that any mixture of suitable feeding stuffs 

 from which a cow can digest 2.5 pounds of protein and 13 

 pounds of non-nitrogenous nutrients per day will constitute a 

 suitable ration and produce a good flow of milk. 



The Wolff standards were introduced into the United States 

 a few years later through the writings of Johnson, Atwater 

 and others, and by the writer's translation of Wolff's book, 1 

 and found wide currency among students of stock feeding and 

 with popular writers. 



792. Modifications of the Wolff standards. That with the 

 progress of investigation modifications should be made in 

 standards formulated fifty years ago was to be expected. From 

 1864 to 1896 Wolff's standards were published annually in 

 Mentzel and von Lengerke's Kalender practically unchanged. 

 From 1897 to 1906 they were continued under the charge of 

 Lehmann, who introduced some additions and modifications, 

 the principal ones being the subdivision of the standard for dairy 

 cows according to milk yield and the distinction between meat 

 and milk or wool breeds in the standards for growing animals. 

 These constitute the well known Wolff-Lehmann standards. 



793. Kellner's standards. Both the Wolff and the Wolff- 

 Lehmann standards, as already noted, were expressed in terms 

 of the so-called digestible nutrients. Kellner, in 1905, in the 

 first edition of his Ernahrung der landwirtschaftlichen Nutz- 

 tiere, proposed the system of calculation by means of starch 

 values (772) which has since been associated with his name, 

 and formulated a table of feeding standards expressed accord- 

 ing to this new method. 



1 Manual of Cattle Feeding, 1880. 



