22 BTJLLETIF 109^, U. S. DEPAETMEI^T OF AGRICULTURE. 



substances. As ordinarily practiced, aeration has a double purpose — 

 first, to air the milk ; and second, to lower its temperature. Russell 

 {10) reports "the method certainly has no disadvantages." It 

 should be borne in mind also that feed and barn taints once re- 

 moved are removed permanently by the process. Marshall says {9) 

 "it is best accomplished immediately after milking." According 

 to. Ernst (^), "the aeration of milk permits the escape of carbonic 

 acid, hydrogen, and sulphid of hj'drogen, and supplies the milk with 

 air so that in all probability the development of certain bacteria is 

 checked, which otherwise, if the milk had been filled in containers 

 in a warm and unaerated condition, would have imparted to the 

 milk a sharp disagreeable taste and odor ; the milk would have been 

 ' smothered,' " 



PLACE TO USE THE AERATOR. 



In aerating milk it should be borne in mind that the same condi- 

 tions which favor the escape of odors which the milk contains when 

 drawn from the cow are also conditions which permit the milk to 

 become tainted with odors from the outside. For this reason, aera-' 

 tion should take place in a milk room in which the air is free from 

 bad taints or dust, and which is well ventilated. 



GOOD FLAVORS AND ODORS IN MILK. 



It is important that milk have a good flavor and a good odor. It 

 is probable that some flavors and odors constantlj^ present in milk in 

 time cease to be objectionable to the individual and are taken as a 

 matter of course. In some alfalfa sections of the United States the 

 so-called alfalfa taste is general in milk and in these sections is ac- 

 cepted without comment. 



The work has shown that fine-flavored milk is an individual char- 

 acteristic of some cows. It may lie that whole herds of cows giving 

 milk of desirable flavor will be assembled in the future, and the 

 effort made to fix and perpetuate this desirable characteristic by 

 breeding and selection. 



Preventive measures are always best; therefore dairymen should 

 endeavor, first, to have cows and bams clean; second, to have cow 

 stables properly ventilated ; third, to feed after milking those mate- 

 rials likely to taint milk; and fourth, to decrease feed and barn taints 

 by proper and immediate aeration. Finally, prompt cooling and 

 storing of milk at a low temperature will retard the development of 

 odors from bacterial action. 



As stated before, the cows used in these experiments produced daily 

 approximately 10 pounds of milk each. It is possible that with cows 

 of greater or less production different amounts of silage might be 

 fed with varying results as regards intensity "of the flavor imparted 



