FACTORS THAT AFFECT COMPOSITION OF MILK 61 



then kept for one entire lactation period on the farm of the 

 owner without in any way changing the conditions under which 

 the animals had lived. At the close of this lactation period, ten 

 cows from the herd were purchased and brought to the Univer- 

 sity, where they were fed liberally for two years, records of pro- 

 duction being constantly kept as before. At the end of the two 

 years, seven cows (three had been disposed of) were returned to 

 the farm from which they were purchased and kept under condi- 

 tions practically identical with those of the first year, and records 

 kept as before. That is, the experiment is divided into three 

 parts : (1) on a private farm, one lactation period ; (2) at the 

 University, two lactation periods; (3) on the private farm 

 again, one lactation period. 



" From the above table it will be seen that there were consid- 

 erable variations in the percentage of fat in the various periods. 

 In order to determine the effect upon the percentage of fat of 

 the more liberal feeding while the cows were at the University, 

 the percentage of fat in the milk of each cow for the first and 

 fourth periods (scant ration) has been averaged and compared 

 with the average of the second and third periods (liberal ration) . 

 The results are given in the next table. Only the records of the 

 seven cows that remained in the experiment for the entire time 

 are used in this tabulation. 



"The following table shows that, on the whole, the milk 

 was one-quarter of one per cent richer in fat during the whole 

 time the cows were on a liberal ration. The percentage of 

 fat was therefore increased about 6 per cent. Further, each 

 cow without exception gave richer milk while on the liberal 

 ration. It would seem therefore that in the case of these 

 seven cows the percentage of fat was ' materially and per- 

 manently increased' by the influence of more and better food 

 and that our thesis is answered in the affirmative, so far as 

 it can be answered in an experiment using only a small number 

 of individuals. 



