Other factors associated with both types of forage are : ( 1 ) the 

 feed acceptance level of the cow by date of cut of forage and (2) the 

 minimum amount of forage that will be consumed per cow per day. 



The feed acceptance level of the cow is the combination of forage 

 and grain that she will consume per day, and depends upon the date of 

 cut and whether the forage was rain damaged or not. The acceptance 

 level reflects the quality of the forage by date of cut and weather 

 damage. 



There is an acceptance level for each type of forage (rain damage or 

 no rain damage) by date of cut. Further, a minimum amount of forage 

 will be consumed per cow per day, independent of the type or date of 

 cut. 



Grain Input 



Grain is the second major input used in the production of milk. 

 Purchased grain is not as variable in quality as forage. Therefore, the 

 quality of the grain fed was held constant, while the quantity was allow- 

 ed to vary. These methods Avere considered : ( 1 ) grain constant : I 2 ) 

 milk constant; and (3) constant milk-grain ratio. This means that 3 

 comparisons were made, 1 for each type of grain feeding management. 

 These 3 methods outline the extreme ways that milk can be produced 

 using forage and grain as variables. 



Using the grain-constant method of producing milk, grain was held 

 constant at a fixed number of pounds per cow per day. Forage was fed 

 free choice. Milk production per cow per day varied according to the 

 amount of nutrients supplied by the fixed quantity of grain and the 

 free-choice quantity of forage consumed. 



Using the milk constant method, milk was held constant at a fixed 

 number of pounds per cow per day. The nutrients required to produce 

 this milk had to be supplied by the forage and grain consumed. 



The milk-grain ratio type of management is very commonly used 

 by farmers, and implies that cows will be fed 1 pound of grain for fixed 

 amounts of milk produced. Forage is fed free choice. Less forage is 

 consumed as the date of cut advances; therefore, less nutrients from 

 forage are consumed by the cow. As a result, milk production declines, 

 and the amount of grain fed declines. This becomes a cycle in that: 

 (1) late cut forage is not as palatable as early cut forage and has less 

 digestible dry matter per unit; thus (2) milk production declines be- 

 cause only nutrients consumed are used to produce milk; therefore, 

 (3) less grain is fed, because it is fed according to the amount of milk 

 produced. 



The Milk Production Surfaces 



It was necessary to use 2 production surfaces to describe the x'ela- 

 tions developed from the available data because of the 2 types of forage, 



26 



