230 BUTTER-MAKING. 
of the soft fats than she does later on in the lactation period. 
With this increase in the proportion of the hard fats in the 
advancement of the lactation period, the fat-globules become 
smaller. This, together with the increased hardness of the fat, 
causes difficult churning at times. It can readily be seen that 
the larger the fat-globules are the greater are the chances for 
these globules to strike each other during agitation in the 
churning process. 
4. The nature of the food fed affects the melting-point of 
butter to a considerable extent. Cotton-seed and its by- 
Fig. 140.—The Disbrow combined churn. 
products have been demonstrated thoroughly by several investi- 
gators to cause butter to become hard. When a large amount 
of cottonseed is fed, the butter assumes a crumbly, tallowy, 
hard condition; while linseed meal, and practically all succulent 
foods tend to decrease the melting-point of butter-fat. 
According to the above it can be concluded that the churning 
temperature may vary between wide limits, but the average 
desirable churning temperature under normal conditions is 
