PRODUCING MARKET MILK IN DELAWARE. 6 
was visited for a working day every 30 days throughout the one 
or two years it was under observation. 
By obtaining records on every dairy regularly each month the 
influence of unusual circumstances at the time of any particular 
visit was lessened, and by using the records of all the herds for each 
month complete data for each month, season, and year were ob- 
tained. Data were obtained for two entire years in order to com- 
pare one year with the other in the same section and to increase the 
amount of data for study. 
SEASONAL INFLUENCE OF WINTER AND SUMMER ON COST FACTORS. 
^ince the winter and summer seasons have a marked influence on 
the principal factors entering into the cost of producing milk, the 
results have been computed separately for those periods. The 
months from November to April, inclusive, represent the winter 
season and from May to October, inclusive, the summer season. 
The various tables found in this bulletin are based upon the fig- 
ures obtained during the two years of the study, and the weighted 
average of the 2-year records was used whenever it would more 
accurately express the result. The weighted average was obtained 
by giving to each item a weight proportionate to its importance in 
comparison with the other items making up the average. 
DESCRIPTION OF HERDS. 
During the first year, records were obtained on 15 herds. The 
size of the herds was determined by the number of cows kept in the 
herd for 12 " cow-months." " Cow-month " is a term used to ex- 
press the record of one cow in the herd for one month. Computed 
on this basis, the first year's study included 248.7 cows, with an 
average yearly production of 5.556 pounds of milk averaging 3.6 
per cent butterfat. The second year's study included 281.6 cows in 
16 herds, with an average yearly production of 5,326 pounds of milk 
and an average butterfat test of 3.6. The Holstein breed in both 
grade and purebred animals far outnumbered all the other breeds 
combined. Some of the herds had a few Guernseys and Jerseys. 
REQUIREMENTS FOR PRODUCING MILK. 
Wherever possible, the requirements have been expressed in terms 
of pounds of feed and hours of labor so as to eliminate as much as 
possible the effect of fluctuating prices. 
