RULES AND REASONS FOR FARM CARE OF MILK. 115 



be fed than will be consumed in a relatively short time. If the animal has 

 access to such feeds in her manger for a considerable number of hours, a 

 tainted condition in the milk is sometimes observed that would not have 

 been present if the food had been eaten immediately. 



Cows on pasture often eat weeds or plants that impart peculiar and 

 ofttimes obnoxious flavors to the milk. The onion family, represented 

 by the leeks, garlic and wild onions, are notorious in this regard. Cows 

 running in the woods, especially in spring, are liable to have their milk 

 affected from such a source. In some parts of the United States, partic- 

 ularly along portions of the Atlantic seaboard, these wild plants infest 

 the pasture lands to such an extent as to almost ruin the milk supply. 

 Chicory, rag weed and numerous other wayside weeds bother later in the 

 season. Where it is possible to control the access of cows to such places 

 trouble may be easily prevented. 



METHODS OF ELIMINATING TAINTS. 



AERATION. Various methods have been suggested to aid in the elimi- 

 nation or destruction of these obnoxious odors after they have been absorbed 

 by the milk. The most widely discussed of these methods is aeration, i. e., 

 bringing the milk more or less completely in contact with air, thereby al- 

 lowing, it is claimed, an opportunity for the escape of these volatile sub- 

 stances. This method has been most strongly recommended for milk used 

 in cheese making, it being a well established belief that airing the milk 

 improves it for this purpose. 



Aeration as ordinarily practiced has a double effect. Besides airing the 

 milk, it usually lowers the temperature so that the effect of cooling is like- 

 wise secured in a partial degree. Whether the reported benefits of aeration 

 are not in part due to the cooling effect is not well known. Experiments 

 made under the auspices of different experiment stations are contradic- 

 tory in their results and a satisfactory explanation of the reported benefits 

 of aeration is yet to be made. 



The results of the system as determined by practical experience should 

 have great weight, and notwithstanding the failure to satisfactorily ex- 

 plain the apparent discrepancies between practice and carefully controlled 

 experiments, the method certainly has no disadvantage. Care should be 

 taken to aerate in a thoroughly pure atmosphere, that is, free from dust and 

 taints of all sorts; otherwise more harm than good may come from the 

 process. 



PASTEURIZATION. Driving off the odors by heating the milk has also 

 been highly recommended. In fact, this claim is often made as one of the 

 advantages accruing from the pasteurizing process. In heating milk the 

 various gases, as carbon dioxide, oxygen, etc., that are dissolved in theserum 

 are driven off, and it is undoubtedly true that other substances of a gaseous 

 nature would be eliminated, at least, in part by this treatment. Even an 



