New York Agricultural Experiment Station. 59 



forts of hot weather and annoyance by flies. Fortunately we 

 have a means of comparison in our Station herd. These cows 

 are kept in the quiet of the stables most of the time and are 

 protected as much as practicable from conditions which cause 

 disturbance in any way. They are supplied all the time with 

 an abundance of succulent and nutritious food. If we examine 

 the milk produced by these cows during the summer of 1895, we 

 find that there was marked uniformity in composition, taking 

 the relation of fat and casein as our basis of comparison. Taking 

 the relation of fat to casein in May as 100, and comparing this 

 with the following months, we have the following: — 



May ... 

 Juue .. . 

 July... 

 August 



Factory 

 herds. 



100 

 97 

 88 

 84 



Station 

 berd. 



100 

 100 

 100 

 100 



Thus we see that while the relation of fat to casein in the milk 

 of the Station herd was very uniform, there was a continuous 

 marked change in the milk of the factory herds. Stated in 

 another way, the cheese-producing efficiency of the milk was not 

 affected by the season in case of the Station herd, while in case 

 of the factory herds, there was marked change in the direction 

 of loss. 



The changes in the milk of the factory herds cannot be ac- 

 counted for on the ground of advancing lactation. In the ab- 

 sence of other disturbing conditions, it appears that the relation 

 of fat and casein in milk is fairly uniform with a general ten- 

 dency for the casein to increase in relation to the fat, especially 

 toward the end of the period of lactation. In the factory herds 

 the reverse is seen during the summer months. 



In regard to the yield of milk and its variations from month 

 to month, we know that lactation exercises a fairly definite influ- 

 ence. Again, we will make comparison of our Station herd with 

 the factory herds. It is not far from truth to say that the month 



