10 BULLETIN 955, U. S. DEPARTMENT OF AGRICULTURE. 
The cost for upkeep and repairs was obtained by keeping a record of 
actual expenditures made during the year. Necessary expenses, 
such as roofing and painting, which do not occur every year, were 
determined by prorating the costs over the length of life of the roof 
or the duration of the paint and charging only the yearly share of 
such expense. 
EQUIPMENT. 
Because of rapid wear and breakage farm tools and equipment 
have a short life, which explains the depreciation charge of 30.4 
per cent. The cost of such supplies as washing powder, coal oil, 
and gasoline amounted to $1.99 per cow per year. 
Milk produced by a purebred cow has no greater value than that 
produced by a grade cow. Raising purebred cattle is a separate 
business involving larger investment and operating costs and re- 
sulting in larger credits for calves dropped. To avoid the effect of 
the purebred business upon the requirements for producing milk, 
the purebred cows found in the herds, which consisted mainly of 
grade cows, were given values equal to those of grade^ cows of cor- 
responding production. Purebred calves were likewise credited as 
grade calves from grade cows of corresponding production. 
At the beginning and end of the year each cow was given an 
inventory value. The first value was based on the price for which 
the owner thought he could replace her. In order to avoid the 
influence of market conditions her subsequent value remained the 
same unless her owner thought that she had become a better or a 
poorer cow. However, it was impossible in many cases to prevent 
the market condition from influencing the judgment of the owner. 
To obtain the depreciation on cattle, the value of every cow that 
entered the herds during the year was added to the inventory at 
the beginning of the year; from this result was subtracted the total 
value of the cows at the end of the year plus the price received for 
cows sold during the year. 
Taxes chargeable to the dairy were taken from the official tax 
records. 
PERCENTAGE COMPARISON OF FACTORS INVOLVED. 
A comparison of the cost of producing milk in winter and in 
summer, and the items chiefly responsible for this variation are 
presented in Table 8 . 
The totals of the cost of production in the first two columns show 
that it cost 4.6 per cent more to produce milk in winter than it did 
in summer. The feed, bedding, and pasture cost was 5.2 per cent 
