FEEDING FOR MILK PRODUCTION 277 



It is also known that the cow needs all of these constituents. 

 The next question is as to how much of each constituent is 

 needed to supply what the cow must have to enable her to 

 produce the maximum amount of milk. This problem has 

 been worked on for many years by able investigators, and a 

 fairly accurate knowledge of the subject has resulted. A 

 statement of the food requirements of the animal is known 

 as a feeding standard. 



The feeding standard prepared by Wolff, and known in the 

 revised form as the Wolff-Lehmann standard, has been the 

 most widely used. The standard of Haecker has also been 

 widely used in this country, and is an improvement over the 

 first mentioned, in so far that a provision for maintenance is 

 first made, then an allowance added according to the amount 

 of milk produced. In using these feeding standards it was 

 assumed that a pound of digestible protein in one feed stuff 

 is equal to that amount in every other. For example, a 

 pound of protein in clover hay is considered equal in feeding 

 value to the same amount of protein in oil meal. More recent 

 work by Kellner and Armsby has shown that this is erro- 

 neous and that a pound of digestible nutrients in a concentrate 

 like corn or oil meal is more valuable than the same amount 

 in a coarse food like ha^. This difference in value is due to 

 the increased expenditure of energy consumed in digesting 

 the coarser feeds. The latter authorities also consider that 

 a portion of the protein which is in the form known as amids 

 cannot be used by the animal. Table 10 gives the digestible 

 protein and energy value of common feeding stuffs according 

 to Armsby. 1 



Armsby has also prepared a tentative feeding standard for 



1 Farmers' Bulletin 346, U. S. Dept. of Agric. 



