INFLUENCE OF THI PLANE OF NUTRITION’ UPON MILK 75 
are not satisfactorily explained by the hypothesis that under- 
feeding causes a transfer of tissue fat to the mammary glands. 
Blood fat analyses made during extreme underfeeding in the 
ease of two cows failed to show any increase in the amount of 
fat carried by the blood stream in comparison with normal 
conditions in the same animals. 3 
The effects of underfeeding on the composition and proper- 
ties of milk and butter fat show the importance of controlling 
this factor in feeding experiments involving the effects of 
specific feeds on the composition of milk and butter. 
The effects of underfeeding must be taken into account 
in the interpretation of all data involving variations in the 
composition of milk and butter fat due to specific conditions 
of the cow, specific environments of the cow, changes in the 
feed of the cow, or to feeds of specific character. 
