1909.] PUBLIC DOCUMENT — No. 31. 81 



In the third preliiiiiuaiy period, lasting from March 9 to 

 30, during which time the soy bean meal was removed and the 

 oil added to the ration of Herd II., total solids and fat deter- 

 minations were made in order to note any changes which might 

 result during the process. No change could be observed, how- 

 ever, that might be attributed to the oil. In the three weeks 

 of the period proper it is to be noted that the total solid matter 

 in the milk produced by Herd I. had increased a little (from 

 14.8S in the first period to 15.12), due to the advance in lac- 

 tation. The milk produced by Herd 11. in the third period 

 l^roper remained remarkably even in composition, and one 

 could not say that the addition of the oil to the ration pro- 

 duced any noticeable effect in varying the proportions of its 

 several constituents. 



The above results are somewhat different from those secured 

 with linseed,^ cotton-seed,^ and corn oils,^ where there appeared 

 to be an increase in the fat content of the milk (.15 to .50 per 

 cent.) which lasted, however, in two out of three cases only for 

 a week or two; the nitrogen was, on the contrary, slightly de- 

 pressed. 



After the completion of the third period the soy bean oil 

 was suddenly remo'ved and the composition of the milk analyzed 

 and recorded. It will be seen that the percentage of fat in the 

 milk of Herd II. suddenly dropped several tenths of a per 

 cent., and after an interval of ten days began to come back to 

 normal. Similar results were secured in previous experiments. 

 This, it would seem, indicated that the fat in the food helped 

 in the formation of the milk fat, and its sudden removal caused 

 a temporary milk fat decrease. The animal, however, soon 

 corrected the condition by making the fat from other sources. 



Flavor of the Mill-. — A sample of each cow's milk was 

 taken several times during the second and third periods, and 

 tested for odor and flavor, by two different parties, both when 

 cold and warm. The milk was taken by one of the chemists 

 immediately after it had been drawn, and was placed in thor- 

 oughly cleaned and well-dried glass-stoppered bottles. Each 

 cow was given a number, so that the parties making the ob- 



1 Hatch Experiment Station, 13th report, p. 19. 



2 Hatch Experiment Station, 14th report, p. 1G4. 



3 Hatch Exijeriment Station, 16th report, p. 50. 



