FARM DAIRYING 409 



(5) The size of fat globules in milk varies according to the 

 breed. The larger these globules, the more quickly and easily 

 they unite. Hence their effect on the time required for churning. 



(6) The production of large and small fat globules varies in 

 individual cows. Some produce a larger percentage of large 

 fat globules than others. Hence the churning time is affected 

 by the individuality of the cow. 



(7) The stage in the period of lactation is also an influencing 

 factor because of its effect on the size of the fat globules and for 

 other reasons not yet fully understood. In the earlier part of 

 the milking period cows produce milk containing larger fat 

 globules than they do during the later months. 



(8) The effect of feed upon churning is due to its effect upon 

 the composition of the fat globules. It is generally conceded 

 that a green succulent feed, like grass, green corn, ensilage, 

 and the like, tends to increase the softness of the fat globules, 

 while a dry feed, such as grain and hay, causes a harder butter- 

 fat. 



(9) The acidity of cream probably affects the time and com- 

 pleteness or efficiency of churning. The ripened cream will 

 probably churn in less time and more efficiently than sweet 

 cream; hence, if it is necessary to churn quantities of cream 

 which have been collected from day to day, as is almost uni- 

 versally true in farm butter-making, they should be mixed 

 together a few hours before churning in order that the acidity 

 will be uniform throughout the whole quantity. 



While all these factors affect the time and labor required for 

 churning, the most important ones are the percentage of fat in 

 cream, the temperature of the cream, and the fullness and speed 

 of churn. If these four factors are carefully controlled, little 

 difficulty in churning will be experienced. The cream for 

 churning should contain at least 25 per cent butter-fat, should 

 be at such a temperature that it will churn in twenty-five to 

 thirty minutes, giving a firm, granular butter, and should be 



