4 BULLETIN 858, U. S. DEPARTMENT OF AGRICULTURE. 



"net cost of jwoduction" are used, these terms do not include the 

 charge for managerial ability. If it is desired to include managerial 

 ability as a cost of production, when determined by any method 

 selected, this amount may be added to the cost of production. 



INFLUENCE OP SEASONS ON COST FACTORS. 



Since 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 whiter 

 season, and from May to October the summer season. This division 



Fig. 1. — Better breeding saved labor. The owner of this herd of cows, averaging 9,200 pounds of 

 milk annually, had to feed and milk only 9 cows to obtain as much milk as 12 average association 

 cows produced. 



of time was based directly on the change in methods of herd manage- 

 ment made in November and May. 



The various tables in this bulletin are based upon figures ob- 

 tained during the 2 years of the study, and all results are expressed 

 in weighted averages in which the weights represent the relative 

 importance of the separate items averaged. 



DESCRIPTION OF HERDS. 



During the first year the 16 herds on which records were tabulated 

 contained 334 grade and purebred cows, mostly of the Holstein 

 breed, which produced on the average 6,877 pounds of milk testing 

 3.8 per cent butterfat. In the 21 herds included in the study the 

 second year there were 404 cows of approximately the same breeding 



