CHURNING AND WASHING BUTTER. 229 



butter is expressed, and the overrun will be lessened to a great 

 extent without increasing the commercial value of the butter. 



The degree of hardness of the fat in the cream is the govern- 

 ing factor in deciding the churning temperature. The churn- 

 ing temperature will vary a great deal in different localities. 

 The hardness of the fat depends upon (1) the season of the year; 

 (2) the individuahty of cow; (3) the stage of lactation period; 



Fig. 139. — The Squeezer combined churn. 



and (4) the kind of food fed to the cows. All these factors 

 influence the melting-point of butter-fat. The higher the 

 melting-point of butter-fat is, the higher the churning tempera- 

 ture, and the lower the melting-point of the fat, the lower the 

 churning temperature. 



1. During the spring the cows yield milk containing a larger 

 proportion of soft fats; consequently the churning tempera- 

 ture is always lower in the spring than in the fall or winter. 

 During winter, when the cows are fed on dry food chiefly, the 

 harder fats increase in quantity, and consequently a higher 

 churning temperature is necessary during that time. 



2. Some animals produce milk containing a larger proportion 

 of softer fats than do other animals. It is said that the differ- 

 ence in this respect is more marked in certain breeds. It is 

 maintained that the cows of the Jersey breed produce milk con- 

 taining a larger proportion of the softer fats than do any of the 

 other breeds. 



3. The period of lactation also affects the melting-point of 

 butter-fat. When a cow is fresh she yields a larger proportion 



