what the herd could consume during the pasture season. The slope of 

 each milk response reflects only the change in milk output due to 

 changing forage and grain inputs. Six combinations of grain and 

 forage feeding were included as processes for each of the three milk 

 response functions. 



One dairy replacement was required for every four cows. This 

 assumes a 4-year herd life for milking cows. The replacements could 

 be either purchased or raised. Replacements could be raised in com- 

 petition with dairy cows for such resources as stall space and forage 

 or, in each model, a few replacements could be raised in housing 

 not suitable for milking cows and could be pastured in fields not 

 accessible to dairy cows or not suited for hay. 



The heifer calf crop was assumed to be 40 calves available to be 

 raised as replacements per 100 cows. The balance of the heifers 

 available for raising as replacements over the replacement require- 

 ments could be raised and sold or could be sold at birth. 



Other intermediate products and joint products of a dairy farm 

 were considered as saleable. These were hay, cull cows, and bull 

 calves. Hay, heifer calves, and replacements were sold through a sales 

 process. However, the sale of cull cows and bull calves was accom- 

 phshed by subtracting the net return from these alternatives from 

 the cost of keeping a dairy cov/. The reason for the different handling 

 of these products stems from the assumption that hay and replace- 

 ments could be sold in various quantities as determined in the solu- 

 tion, but cull cows and bull calves had to be sold in a fixed proportion 

 with the number of dairy cows kept. Finally, all milk produced was 

 sold through a milk sale process. Table 1 lists the factors which are 

 considered fixed, the factors which are considered variable, the inter- 

 mediate products, and the saleable products for each single solution in 

 the linear programming model. 



Resource Supplies and Restrictions 



In this analysis the cropland resources were held constant at 

 100 acres of cropland of which 50 acres were suitable for corn or 

 alfalfa, and 25 acres were suitable for production of alfalfa. The silo 

 capacity available was not a restriction and was set to be greater than 

 required if all corn land (50 acres) were planted to corn. 



The labor hours supplied by the farm family were taken to be 

 2,252 hours per year. This figure does not include any allowance for 

 overhead time for such tasks as plowing snow, keeping records, re- 

 pairing buildings, attending meetings, etc. This net labor time was 

 distributed throughout four labor periods in proportion to the number 

 of days in each period. The labor available in each period is only that 

 proportion of the total labor which may be devoted to performing 

 the specific operations required by each process. 



