74 MAINE STATE COLLEGE 



is largely on one side, it is to some extent conflicting. Up to the 

 present date, however, the concensus of opinion is as before stated r 

 that the animal is the determinative factor. There are numerous 

 facts in common experience which accord with this opinion. Every 

 farmer recognizes marked differences in the milk of the several 

 animals in his herd and he is well aware that by no sort of manipu- 

 lation of food can he obliterate these differences and reduce the 

 milk of all his different animals to a dead level of quality. What- 

 ever practice he may adopt in feeding he will still have "poor- milk"' 

 cows and ''rich-milk" cows. It is a matter of common observation 

 that certain breeds furnish milk of a characteristic quality and no 

 one has yet discovered a way of converting a Jersey's milk into the 

 kind the larger and more showy Holstein yields, neither do we know 

 how to coerce the latter into supplying us with the richness of color 

 and composition which we have imported from the Channel Islands ► 

 It is reasonable to regard lactation as a function, which, both as to 

 the kind and the maximum quantity of the product, is fixed chiefly 

 by the constitutional limitations of the individual. 



It has been supposed possible for changes in the food to cause the 

 composition of the resulting milk to vary in two wa}*s, viz : by increas- 

 ing or decreasing the percentage of solid matter, and by changing 

 the composition of the solids, as for instance, increasing the fat 

 without a corresponding increase of casein. 



The experiment with cows, the results of which are given in this 

 connection, was planned with reference to changes in the rations so 

 radical as to induce if possible corresponding variations in the char- 

 acter of the milk. The attempt was not to compare a starvation 

 diet with liberal feeding, because no one believes a starvation ration 

 to be wise or profitable, and liberal feeding is universally regarded 

 as a part of the creed of successful agriculture. But while there is 

 a general agreement that the ration should be generous in quantity 

 and agreeable in qualit} 7 , there is much discussion as to the way in 

 which this ration should be compounded and the relative effcet of 

 different mixtures of the nutrients, and so the rations in this exper- 

 iment were made to differ very widely in the relation of the nitro- 

 genous to the non-nitrogenous nutrients. 



The experiment was begun with four cows, one of which was 

 dropped out and results are reported from only three. The three 

 feeding periods covered one hundred and five days, or thirty-five 

 davs each. 



