46 



THE NORMAL COMPOSITION OF MILK 



TABLE XX 



INFLUENCE OF STAGE OF LACTATION ON COMPOSITION 

 BY FOUR-WEEK PERIODS 



scientific interest, it is of comparatively little value to the milk 

 examiner who is required to give an expression of opinion upon 

 analytical results with reference to sophistication. Such sam- 

 ples may be derived from many sources and their composition 

 influenced by many factors concerning which he has little or 

 no information; the examiner is, therefore, more vitally inter- 

 ested in the natural variations from the average than in the 

 average itself. 



Reference has previously been made to various factors which 

 produce variation in the composition of milk but it is advisable 

 to discuss in more detail their effect upon the relative propor- 

 tions of the various constituents. The effect of breed upon the 



proteid , lactose , . -,1,1 f f , 



tj and TT ratios together with the percentage of fat 



fat proteid 



in the total solids is shown in tables XXI, XXII, and XXIII. 



Although some of these results are somewhat discordant, 

 the general tendency is usually in the same direction. When 



