RELATION OF PRODUCTION TO INCOME FROM COWS. 7 
From this curve the income over cost of feed for each 50 pounds 
of gain in butterfat production may be determined. It is well 
known that dairy cows, to be profitable, must be comparatively large 
producers, yet few people fully realize the remarkable rate at which 
income over cost of feed advances as production increases. The 
chart shows that as average butterfat production increased from 
150 to 200 pounds, the average income over cost of feed advanced 
from $26 to $42 ; that is, a gain of 50 pounds in butterfat production 
increased the income over cost of feed $16. or nearly 62 per cent. 
The next gain of 50 pounds raised the income over cost of feed to 
$58, the next to $74, the next to $90, and the next to $106. 
Briefly stated, as production of butterfat increased from 150 to 
400 pounds, the income over cost of feed advanced from $26 to $106, 
Fig. 4. — An Ayrshire herd in the Herndon (V; 
:ow-testing association. 
or exactly $16 for each gain of 50 pounds in butterfat production. 
As butterfat production increased from 400 to 450 pounds the gain 
in income over cost of feed was about $19. For the groups whose 
average production was above 450 pounds the income above feed 
cost was somewhat irregular, which may have been due to the fact 
that the number of records was too small to give dependable aver- 
ages, or there may have been a point beyond which the cows did not 
respond so readily to more liberal feeding. Undoubtedly there is a 
point beyond which it does not pay to feed for increased produc- 
tion, but evidently that point is seldom passed in the feeding of 
cow-testing-association cows. 
As prices of feeds and prices of dairy products rise and fall the 
income over cost of feed also mav rise and fall, but a studv of the 
