Milk Yield of Jersey Cattle. 131 



ment. To illustrate, suppose a herd which has iooo two year 

 olds who have just completed their first lactation is chosen at 

 random. The manager of this herd will wish to know what ani- 

 mals to save for future lactations and the student of farm man- 

 agement desires to know what may be expected for the total 

 production of the animals to enable him to determine the plane 

 to which the herd should be culled for the greatest profit to the 

 owner. 



Perhaps one of the easiest ways to table the necessary in- 

 formation for its readiest uses is to have the summation of both 

 the number of cows and their expected total production. This 

 summation to be from both ends of the range of milk produced. 

 The data for such a comparison are given in table 5. 



If all the cows in this herd are kept to their sixth lactation 

 the average production for each cow for the five lactations would 

 be 25,070 pounds of milk. Noting the summed number of cows 

 in column four if the 217 poorest producers are culled from the 

 herd the cows left in the herd will produce on an average 26,408 

 pounds or an average 5,389 pounds more milk than the culled 

 cows. Again if the dairyman decides to cull but 543 of the 

 thousand animals the production of the 457 remaining will be 

 28,192 pounds or 5,747 pounds more than the culled cows on 

 the average for the summed productions for the five lactations. 



As the records dealt with in this paper are all for the first 

 eight months of lactation it follows that most cows will extend 

 beyond this limit and produce more milk. In using this table to 

 determine what cows may be kept profitably, this fact should be 

 kept in mind. If the dairyman has determined the complete 

 cost of producing his milk a knowledge of the price he receives 

 for it will allow him to determine at once from column three 

 what cows he should keep in the herd. 



In the bulletin following this, the relation of the butter-fat 

 percentage to the age of the cow will be analyzed using the rec- 

 ords for this herd. 



