66 DAIRY FARMING 



total fat in this milk would equal 850X4.2, or 35.70 

 pounds. 



Since butter contains salt, water, casein and only about 

 83% butterfat, it is to be expected that the yield of 

 butter will exceed that of butterfat, provided the losses 

 in skimming and churning are normal. The general 

 rule in estimating the butter yield is to increase the but- 

 terfat by one-sixth. Thus the estimated butter yield 

 of the 35.70 pounds of fat given above would equal 35.70 

 Xi 1-6 or 41.65 pounds. The difference between the 

 butterfat and the actual butter yield is known as the 

 "overrun." 



Estimating the Cost of Feed. The final test of the 

 value of a cow is the economy of production. In addition, 

 therefore, to knowing the butterfat yield, we must also 

 know the cost of the feed she consumed in producing it. 

 Obviously a daily weighing of the feed, especially as 

 concerns roughage, is not practical upon most dairy farms. 

 If the feed which each cow receives is weighed about 

 twice a month an approximate estimate of the feed 

 consumed can be obtained by considering the weighed 

 amount of feed as the average daily consumption for the 

 month. To illustrate, let us suppose that cow No. X is 

 doing full work on a ration consisting of 8 pounds of 

 wheat bran, 2 pounds of cotton-seed meal, 40 pounds 

 of corn silage and 8 pounds of corn stover. By carefully 

 observing the volume of the weighed amounts of each 

 feed, approximate quantities may be measured for two 

 weeks, after which a day's feed is again weighed and the 

 measuring continued for the remainder of the month. 

 In this way an approximate estimate of the quantity of 

 feed consumed for the month can be obtained with a small 

 amount of labor. By multiplying the total quantities 

 of the different feeds fed during the month, by their 



