RELATION OF PRODUCTION TO INCOME FROM COWS. 3 
452 active associations in the United States. The map (fig. 2) shows 
the location of these associations. 
HOW THE RECORDS WERE STUDIED. 
The individual cow record includes the name, breed, age, and 
weight of the cow. It also includes date of freshening, names of 
dam and sire, months in milk, pounds of milk produced, butterfat 
test, pounds of butterfat, price of product, total value of product, 
feed consumed, days on pasture, cost of pasture, cost of roughage, 
cost of grain, income over cost of feed, returns for $1 expended for 
feed, feed cost per pound of butterfat, and feed cost per 100 pounds 
of milk. 
In making the herd and association summaries here discussed the 
records of all cows on test 4 months or more were included. That is 
Fig. 2. — Location of the 452 cow-testing associations in the United States, July 1, 1921. 
the way such summaries are made by the testers in nearly all the 
cow-testing associations in the United States. In all other tabula- 
tions only the records of cows that were on test 12 consecutive 
months and had breed and age given were used. The reason for dis- 
carding the shorter records in making tabulations was to avoid pos- 
sible error due to the use of such records. The possible error due to 
a use of such records, however, is probably negligible, as average 
yield, cost, and income proved to be about the same per cow-year 1 
when the records of all cows on test were included as when only the 
records of those on test 12 months were included. (See Table 1.) 
This indicates that the herd and association summaries as now ob- 
1 See footnote to Table 1. 
