THE FEEDING OF MILCH CATTLE 333 



food may contain more fat (up to lib.). Without 

 exception it has been shown in these experiments, 

 as in the older ones, that the food fat has a power- 

 ful influence upon the properties of the milk fat. 

 It has, indeed, been long known that certain fatty 

 foods render the butter soft, whilst others tend to 

 harden it, and advantage has been taken of this 

 to improve the milk fat by feeding certain oil cakes. 



The more a certain fat predominates in the ration, 

 so much more do the properties of the butter fat 

 approach those of the food fat. In the feeding of 

 sesame, cocoa-nut and almond oils, it has been 

 noticed that the butter fat which was obtained 

 behaved on chemical analysis like a mixture of 

 butter with the various oils. Similarly, in the 

 experiments just recorded with rice meal the fat 

 of the milk was found to be soft and greasy and to 

 possess properties quite different to those of the 

 fat got from the rye meal feeding. These peculiari- 

 ties are only observed to take place gradually ; the 

 complete change may require as much as 2-3 weeks. 

 Thorough investigations have shown that those com- 

 ponents of the food fat which otherwise are not 

 found in the body, e.g. linoleic acid or phytosterin, 

 do not pass into the milk. The only change in the 

 milk fat is that of the proportion between those 

 liquid and solid fats which under normal conditions 

 take part in the formation of milk. 



However much of any fat may be given in the 



