220 THE CREAMERY PATRON'S HANDBOOK. 



seem to show that some foods have more effect upon milk production than 

 others. In all cases the influence is within narrow limits, and can all 

 probably be accounted for by the general effect upon the body, or by one 

 food being more palatable than another and therefore more agreeable to 

 the animal. The effect upon milk is probably no greater than it is upon 

 the body as a whole. 



The discrepancy between the results obtained by different experimenters 

 may often be accounted for by the difference in the method of conducting 

 the experiments. The usual length of time given to each period in 'a feeding 

 experiment is ten days or two weeks. Many foods have a temporary 

 stimulating effect, which food naturally shows in such short-period ex- 

 periments, and which would disappear if the period were continued for a 

 longer time. 



The duration of the period, which should be given to an experiment, 

 was also studied at the Vermont Experiment Station. Their results show 

 that the period should be about four weeks, in order to make a comparison 

 of quantity, and that the period should be six weeks or more in order to 

 get a comparison in quality. This is another evidence of the slow rate 

 at which physiological changes take place in an organ having a fixed habit, 

 and also the folly of drawing conclusions from short experiments upon 

 animals. 



EFFECTS OF CERTAIN FOODS AND DRUGS. 1 A great many substances 

 may be transmitted to the milk. The volatile fats that are derived directly 

 from the food may give either desirable or undesirable flavors to the milk. 

 The characteristic flavors we esteem are due to the grasses, clover and 

 like fodders, while the undesirable are due to leek, garlic, onions, turnips, 

 cabbages, fish, etc. We also find poisonous substances such as camphor, 

 turpentine and camomile, aloes, arsenic, lead and tartaric acid transmitted 

 to the milk. Milk to which aloes, mercury and copper have been trans- 

 mitted, frequently is injurious. If proper precaution is taken the undesirable 

 flavors and detrimental effects may be easily obviated, since all these flavor- 

 ing oils pass off through the excretory channels in a comparatively short 

 time. We shall find them present in the greatest amount, not only in the 

 milk but in all the tissues of the animal during the time the fodder containing 

 them is undergoing digestion, and by the time digestion is completed, the 

 volatile products will have almost entirely passed away. Thus, if care is 

 taken in feeding so that it will be performed at least eight to ten hours 

 before milking, there will be slight danger of contaminating it. If milking 

 should occur in four or five hours, the milk will have an undesirable flavor. 

 Taking advantage of this, and feeding the cow immediately before or after, 

 dairymen are often enabled to feed large quantities of turnips, and even 

 onions without contamination of the milk. The presence of wild garlic 



1 Experiment Station Record, Vol. V., p. 973. 



