THE COST OP CATTLE 3 1 



COWS, and n the years of usefulness, was decided upon.. A 

 definite value for w is a problem that is attended by the diffi- 

 culty of obtaining a figure that may be substantiated with 

 actual figures. The length of use of a cow in herds where 

 records of production and feed consumed are not kept can 

 not be used, for it is not possible to tell without these data 

 when the end of the cow's usefulness has come. This no doubt 

 also largely accounts for the fact that during recent years the 

 length of service of a cow apparently has shortened. There- 

 fore records of cow-testing associations are resorted to. The 

 actual ages when the cows are discarded are not recorded, 

 but the ages of the cows are given. In records on file in the 

 Dairy Division of the U.S. Department of Agriculture the 

 ages of 13,856 cows in associations are given. These represent 

 cows in different sections of the country, kept under different 

 conditions of feeding and management, and in some cases 

 represent the same group of animals for six or seven years. 

 The ages of particular cows do not indicate definitely when 

 these particular cows will die or become unprofitable, but the 

 ages of great numbers indicate the probable length of life. 

 For the determination to be more exact and similar to the 

 method used by life insurance actuaries, a record of the cows 

 of the different ages that die during any particular year is 

 also kept. Owing to the large number of cows recorded and 

 the long period of years covered, it is assumed that the aver- 

 age age at exit can be calculated from the number living at 

 the different ages. In some sections a greater proportion of 

 the cows may have been discarded the first year of the asso- 

 ciation, though it will be seen that in the associations that 

 have been running for six and seven years the number of old 

 animals does not increase. The following table gives the ages 

 of cows in the 52 cow-testing associations reporting the ages 

 of the 13,856 cows recorded by the Department of Agriculture: 



