THE RELATION OF FOOD TO MILK-FAT. 



Can the per cent of fat in milk be increased through changes in 

 the food of the cows ? This is a question about which there has 

 been more debate and which lias been the subject of more experi- 

 mentation than any other problem relating to the production of 

 milk. Some experiments have seemed to indicate that certain foods 

 possess the power of increasing the proportion of fat in milk, while 

 others, and much the larger number, show that the variations in 

 the quality of milk are not traceable to the food. All who are 

 familiar with the handling of milk know^ that variations in the per 

 cent of fat do exist and this with the same cow on the same feed 

 and under uniform environment. AVhy the qualit}- of milk fluctu- 

 ates so widely under conditions which to all outward appearances 

 are the same, has never been determined experimentally. The 

 sacretion of milk is so intricate and its processes so comj^letely hid- 

 den from view that a clear understanding of them seems quite 

 impossible. Nevertheless all careful experiments conducted with a 

 view io solve the problem are valuable even though only negative 

 results be obtained and although ihe conclusions reached may be 

 more or less conjecture. 



Experiments conducted for the purpose of determining the ]*ela- 

 tion of food to milk production have usually shown that where a 

 sudden and radical change in the food has taken place, this change 

 has been accompanied by a more than ordinary variation in the per 

 cent of fat This variation may be either an increase or a decrease. 

 After the cows become accustomed to the new feed their milk 

 returns to its former average per cent of fat, which may be called 

 the normal per cent. Such phenomena would seem to indicate that 

 the per cent of fat in milk is subject to the peculiar constitution of 

 the cow and that she will give milk of a certain average composi- 

 tion so long as nothing occurs to disturb the " even tenor of her w^ay." 



A definite knowledge of the relation of food to milk-fat would 



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