60 



FEEDING STANDARDS AND THE DAIRY COW. 



What was probably the first attempt at formulating a ra- 

 tional feeding standard for farm stock was in 1810, when Thaer, 

 the father of German agriculture, introduced what was known as 

 "hay equivalents" in which various feeding stuffs were compared 

 with hay as a standard. The chemical composition of feeding 

 stuffs was imperfectly known and no comparison on the basis of 

 chemical composition could be made. Later Grouven formulated 

 standards based upon chemical composition, and it was not until 

 1864, as a result of the work of Henneberg and others that Wolff 

 based standards upon chemical composition and digestibility. 



The more recent Wolff-Lehmann standard for a 1000-pound 

 cow giving 22 pounds of milk daily requires the following pounds 

 of nutrients : 



Up to the present time the Wolff-Lehmann method of figuring 

 rations has been generally taught in our agricultural schools. 



More recently, however, various investigators have recog- 

 nized that there were certain factors which had not been considered 

 in this method of formulating rations. Haecker of the Minnesota 

 station, after a long series of experiments, concluded that the 

 amount of nutrients needed depended not only upon the size of 

 the animal and quantity of milk produced, but also upon the qual- 

 ity of the milk, and has published tables giving the amount of 

 nutrients necessary for cows producing milk of varying richness, 

 also taking into consideration the weight of the animal and amount 

 of milk produced. 



Kellner, of Germany, and Armsby, of Pennsylvania, have_ 

 approached the problem from, a somewhat different standpoint. 

 They have shown that the value of a feedstuff is measured not 

 only by its composition and digestibility, but also by the loss of 

 energy employed in the processes of mastication, digestion and 

 assimilation. The total energy in a feedstufi' minus the energy 

 thus used has been termed by Armsby net available energy. 



Kellner uses as a unit for measuring net available energy 

 one pound of digestible starch, and the values of other feedstuffs 



