30 MILK PRODUCTION COST ACCOUNTS 



the average is estimated as 5.8 years. The statement is made 

 by Thompson that this is perhaps a more reliable figure. 

 Studies in farm management by the U.S. Department of 

 Agriculture ^ show that the dairy cows of Chester County, 

 Pennsylvania, remained in the herd 4.34 years, while in Lena- 

 wee County, Michigan, they remained 4.52 years. Four, five, 

 six, and seven years are given by different authors as the 

 average life of a cow in the dairy herd. There is no doubt 

 considerable difference in the productive life of a cow, due to 

 varjdng standards of production. By one dairyman under 

 certain conditions a cow may be considered a profitable ani- 

 mal, while with another under different conditions the same 

 production would be unprofitable. In the studies made by 

 the Department of Agriculture valuable data on the rate of 

 depreciation of dairy cows have been assembled. The results 

 are based upon the operations of 643 farms in Chester County, 

 Pennsylvania. The data are offered to form a basis of obtain- 

 ing the approximate average charge which must be made for 

 depreciation in cows, and the authors say: "This method may 

 be apphed to an individual herd of cows as weU as to the 

 average of a large number of herds." The average annual 

 loss in Chester County on dairy cows was 11.82 per cent of 

 the average of the inventory value for the beginning of the 

 year. Similar calculations for Lenawee County, Michigan, 

 gave the annual depreciation as only 4.07 per cent. This dif- 

 ference is due to the difference in price at which cows are 

 bought and sold in the two localities. In Michigan the aver- 

 age price paid for cows was $48.48 and the sale price of the 

 discarded cow $42, while in Pennsylvania the cost was $63.84 

 and the sale price $37.36. 



Although these data are valuable, the percentages can not 

 be used except under the same conditions and prices. This 

 is seen by the great difference in the percentages for Pennsyl- 

 vania and Michigan. In an attempt to get a method that 



could be used under all conditions the formula ~. where x 



n ' 



represents the cost of the cows, y the sale price of discarded 

 ' U. S. Dept. of Agr., Professional Papers, Bull. No. 341. 



