Cows' MILK. 317 



% 

 Milk sugar ... ... 4*75 



Casein ... ... 3'00 



Albumen ... ... 0-40 



Ash ... ... ... 0-75 



Co lost nun. The first milk after calving is known as colos- 

 trum, or "beestings," and is essentially differerent from 

 normal milk. 



It is a yellow liquid, with strong pungent taste, containing 

 large numbers of small clusters of cells" colostrum granules" 

 which vary in diameter from -005 to -025mm. and appa- 

 rently result from the breaking up of the milk glands. 



Engling* gives the composition of the colostrum of 22 cows 

 as varying between 



Fat ... ... 1-88 to 4-68 



Casein ... ... 2-64 to 7'14 



Albumin ... ... 11-18 to 20-21 



Sugar ... ... 1-34 to 3'83 



Ash ... ... 1-18 to 2-31 



Total solids ... 24-34 to 32-57 



Specific gravity ... 1-059 to 1-079 



The fat of colostrum has a higher melting point (40 46) 

 and contains less of the volatile fatty acids than ordinary milk 

 fat. The sugar present is largely grape sugar. Urea has 

 been found in colostrum. The ash differs from that in normal 

 milk in the smaller amount of potash and the much larger 

 quantity of phosphorus pentoxide (up to 41-4%). The liquid 

 secreted by a cow gradually changes day by day until in four 

 or five days it approaches normal milk in composition, though 

 the "colostrum granules" can be detected in the milk for 

 14 days or more after calving. 



Influence of breed. Great variations, especially in the pro- 

 portion of fat, are shown by the milks of different races. The 

 following numbers were obtained at" the New York Experiment 

 Station in 1891f: 



* .lour. ('hem. Soc. 1879, abst. 815; also Ladenburg's Hamlworterbuch tier Chemie. 

 t r. Report of Director, p 141. 



