20 HATCH EXPERIMENT STATION. [Jan. 



— a natural increase, due to the advance in the period of 

 lactation; and in Herd II. from 4.32 to 5.15, or .83 per 

 cent. The percentage increase in Herd I. Avas 11.6 })er 

 cent, and in Herd II. 19.2, showing that Herd II. made the 

 greater average increase. The total solids increased al)out 

 the same in each herd. The average nitrogen percentage 

 increased for Herd I. from .535 to .573, in about the same 

 proportion as the total solids; while Herd II., instead of 

 showing an increase, had a slight decrease. The ash remained 

 practically unchanged. In the third period there was a slight 

 decrease in the total solids and fat of Herd I., and a very 

 noticeable decrease in the fat of Herd II. The nitrogen per- 

 centage of Herd II. in this period increases to about the average 

 produced by Herd I. in the second period. To note, how- 

 ever, the full effect of the excess oil ration, one must observe 

 the weekly analyses of the milk of both herds in the excess 

 oil period. For example, the last fat test in the normal oil 

 period was 4.59 per cent, for Herd L and 4.52 per cent, for 

 Herd II. The first fat test in the second period was 5.07 

 for Herd I. (receiving the normal oil ration) and 5.56 for 

 Herd II. (receiving the excess oil ration). During this 

 entire period Herd I. showed little variation in fat, and 

 averaged 5 per cent. Herd II. increased from 4.48 to 5.56 

 at the beginning of the excess oil period, and then grad- 

 ually decreased, until at the close of the period it tested 

 4.93 and averaged 5.15 per cent, of fat. When it is remem- 

 bered that the figures given represent the mixed milk of five 

 cows, it seems safe to conclude that the excess of oil did in- 

 crease the percentage of fat in the milk, but the increase was 

 only temporary, the fat percentage gradually dropping back 

 to an amount parallel with Herd I. The nitrogen percentage 

 of Herd II. in the second period did not increase so rapidly 

 as did the fat. At the beginning of the period it was less 

 than at the close of Period I., and did not begin to increase 

 until near the close of the period. In the third period it 

 was apparently normal again. 



One might suppose that the fat increase in the case of 

 Herd II. could be accounted for by the shrinkage in milk 

 production. The shrinkage, however, was no more than 



