No. 7. DEPARTMENT OF AGRICULTURE. 271 



moderate quantities directly after milking no bad result is noticed, 

 because in this case the system has had time enough to eliminate 

 the malodorous material. 



There is another feed — silage — that is fully as strong in odor as 

 onions, and to some persons, even more unpleasant, and yet a cow can 

 consume large quantities of even the rankest silage and produce milk 

 without a trace of the silage odor. 



This is denied by many dairymen, but nevertheless it is a fact. 

 When a man says that he is having trouble with his milk on account 

 of the feeding of silage, he is charging himself with carelessness, 

 for it is certain that the bad flavors entered the milk after it was 

 drawn from the cow. The silage odor is very penetrating. It hangs 

 to the hair of the cow and the garments of the milkers; it fills the 

 air of the stable. When silage is fed just before milking and then 

 the milking done without washing the hands, the milk is almost sure 

 to be tainted. Milk left in the stable easily absorbs the silage odor. 



These odors that enter milk after it is drawn from the cow, can 

 be largely removed by aeration. 'Merely lifting the milk in a dip- 

 per and allowing it to fall in a current of pure air will remove the 

 bad odors, but on a large scale it is better to use some of the modern 

 machines that aerate and cool at the same time. To test this mat- 

 ter with regard to silage, I once divided a lot of fresh milk, putting 

 part in the silo on top of the silage in an open pail, while the rest 

 was submerged at once in ice water. The milk remained in the silo 

 several hours until it was thoroughly saturated with the silage odor. 

 The pail was then removed to the dairy room and fresh air blown 

 through the milk until the air, as it bubbled up, smelled no longer 

 of silage. This milk also was then put in the ice water. The next 

 day samples of each lot were submitted to a large dairy class with- 

 out their knowing which was which. The majority of the class de- 

 cided that the silage milk was the better flavor and had the less 

 odor. 



Why should good milk result from bad smelling silage and poor 

 milk from onions? If a very thin slice of onion, turnip or cabbage is 

 examined under a high-power magnifying glass, the tissue will be 

 seen filled with minute drops of a sulphur oil that imparts the pecu- 

 liar odor and flavor. The system of the cow tries to burn up and 

 get rid of all that would injure the milk, but these sulphur oils are 

 among the most difficult to eliminate from the system and unless fed 

 in quite small quantities, produce a bad efl'ect on the milk. On the 

 other hand the odor and taste of silage are connected with the acids 

 of fermentation, and are easily destroyed by the cow. When silage 

 first came into use, some persons claimed that the large quantity of 

 acid it contained must be injurious to the health of the cow. A per- 



