328 THE FEEDING OF ANIMALS 



428. Wolff's feeding standard. — ^Emil von Wolff seems 

 to have been the first one to give a definite recognition 

 to digestibility as a factor in calculating feeding stan- 

 dards. The standards he proposed were in terms of digesti- 

 ble constituents, the quantities fed to be directly propor- 

 tional to live weight without reference to varying pro- 

 ductivity. It was the Wolff standards that first became 

 known, and somewhat widely advocated, in the United 

 States. Their advocates conceded that they were only 

 approximations to actual nutritive needs and chiefly 

 valuable as suggestions in the compounding of rations. 



429. Kuhn's feeding standard.— The fact that Wolff's 

 standards made no allowances for varying productivity 

 caused them to be severely criticised, and properly so. 

 The most prominent critic was Julius Kiihn, who pro- 

 posed a basal maintenance ration, additions to be made 

 to this somewhat in proportion to the demands for pro- 

 duction. The quantities of digestible nutrients recom- 

 mended by Kiihn ranged between 20 and 23.5 pounds of 

 dry matter, 1.5 and 2.4 pounds of digestible protein and 

 12 to 14 pounds of digestible amides, crude fiber, and 

 nitrogen-free extract, Ktihn holding to the point of view 

 of his time that amides function nutritively as do the 

 carbohydrates. 



430. The Wolff-Lehman feeding standards. — The 

 first standards to recognize, in an extended way, the 

 varying nutritive needs of animals according to produc- 

 tion, are those known as the Wolff-Lehman, which are 

 an attempt to so modify the original Wolff standards as 

 to meet the requirements of cows of unlike productivity. 

 This was certainly a step, in the right direction. 



These standards have been widely used in the litera^ 

 ture of animal nutrition in the United States. 



