COMPOSITION OF MILK. 



175 



The fat percentage of milk not only varies with the differ- 

 ent breeds but also in different portions of the same milking, 

 as shown in the following table from Aikman (l). 



TABLE vii. 



VARIATION OF SOLIDS IN DIFFERENT PORTIONS OF ONE MILKING. 



It must be borne in mind that in mixed herds the product 

 varies in fat percentage to a considerable degree. Some bot- 

 tles or even cans will be unnecessarily rich in fats at the 

 expense of others which will run below standard. This cir- 

 cumstance may result in the condemnation of the milk, due 

 entirely to careless manipulation, when the average of the herd 

 may be entirely satisfactory. The whole output of a herd at 

 one milking is not mixed in one receptacle and then trans- 

 ferred to cans or bottles. The usual practice is to take the 

 milk of a few 7 cows at a time for bottling. Even under these 

 circumstances there is danger that the fat will rise in the vat 

 under the cooler unless the milk is bottled immediately after 

 cooling. Too much emphasis cannot be placed upon this 

 important point in the handling of any milk and especially 

 with reference to the product of certified dairies. This milk; 

 so frequently modified for infant feeding, should be of uniform 

 composition. 



The difficulties encountered are best obviated by alternating 

 in the stable, or in the order of milking, the cows known to 

 yield milk of high fat content with those known to give poor 

 milk. In the case of the Channel Island breeds and the 

 Holstein-Friesians this is a simple matter. In the case of 

 scrub cows this recognition may not be so easy -and depend- 

 ence must be placed upon the results of the examination of the 

 milk of these cows for fat by the Babcock test. 



