50 



and Table XY. shows the yield of milk by the two lots of 

 COW T S during this period. 



The total daily yield is again greater on the average in 

 lot II. than in lot I., in spite of the rations having been 

 reversed. For this period, lot I. gave an average of 109 pints 

 per day, and lot II. 113*95 pints, or nearly 5 pints per day 

 more than lot I. From the results of Experiment C it seemed 

 fairly clear that the heavy ration fed to lot II. had caused an 

 increase in the milk yield, and if this increase was directly 

 due to the ration, it would be natural to expect the position 

 of the two lots reversed in Experiment D. But such is not 

 the case, for, with two exceptions, the yield is higher through- 

 out in lot II. than in lot I. The advantage, therefore, as 

 far as yield is concerned, is throughout the whole period of 

 the two experiments with lot II. It is true that there is not 

 the same difference on this occasion between the two lots as 

 there was in the preceding experiment, but it is sufficiently 

 great to be perfectly clear. It must be pointed out that by 

 the end of the second period, April 25, the cows were falling 

 off in yield, and it appears as if lot I. was falling off a little 

 more rapidly than lot II. Both lots of cows had calved nearly 

 about the same time, so that there was not much difference 

 in the length of the lactation period between the two lots 

 up to this time and it is important to observe that the heavy 

 ration supplied to lot I. in Experiment D does not appear to 

 keep up the flow of milk any better than the moderate ration 

 given to lot II. The change from moderate to heavy feeding 

 in lot I. caused the yield to go down very considerably for 

 the first week, although it went up again in the second and 

 third weeks, after which it dropped once more. Assuming 

 the increase during these two weeks to be due to the heavy 

 feed, it is clear its effects were only temporary, and it is a 

 significant fact that, with the exception of the third week 

 mentioned, lot I. on the heavy ration does not come up to 

 where it stood at the end of the preceding experiment on the 



