1909.] PUBLIC DOCUMENT — No. 31. 81 



111 the third i)rcliniiiiary period, histiiig from llarch 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 jji-odueed by Herd II. in the third period 

 proper 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 

 Avitli linseed,^ cotton-seed," and corn oils,'^ where there appeared 

 to be an increase in the fat content ofthe 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- 

 l^ressed. 



After the completion of the third period the soy bean oil 

 was suddenly removed 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 Milk. — A sample of each cow's milk was 

 taken several times during the second and third ])eriods, 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 draAvn, 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 Kxperitiu-nt Station, 13th report, p. 19. 

 s IIal<-h Kxppriniont Station, 14th report, p. 164. 

 s Hatch Experiment Station, IGtli rei)ort, p. 50. 



