MILK AND ITS HYGIENIC RELATIONS 



Colostrum is a more viscid fluid than the later milk. Some of 

 the constituents of -milk are present in higher proportion, and cer- 

 tain properties are possessed by milk in the early days of lactation 

 which are not found later. These are considered in the chapters 

 dealing with the constituents or properties concerned. 



The protein and the salt content are higher in colostrum than 

 in the later milk. Some observers find that there is rather more 

 fat in colostrum than in the later milk, but this appears not to be 

 a constant feature. The number of cells found in colostrum is 

 frequently higher than in later milk. 



The composition of the colostrum of cows is hardly material 

 to the present purpose, as it is not used for infants and is not a 

 marketable commodity. Generally, the divergences in composition 

 of colostrum from that of average milk are similar to those occurring 

 in human milk. 



There is no doubt that colostrum is of primary importance to 

 the young animal, and there is no way of replacing it. An infant 

 deprived of the colostrum of its mother must endeavour, not always 

 with success, to make up later the disadvantage under which it 

 has laboured at the start. 



Practical difficulties are encountered in obtaining samples of 

 human colostrum for estimation. The infant can usually succeed 

 in obtaining an appreciable amount of colostrum before it is possible 

 to obtain any artificially, since suckling almost certainly empties 

 the gland more completely than is otherwise possible. The differ- 

 ences in fat content between the milk at the beginning and end 

 of suckling are very considerable, and this renders the estimation 

 of the fat of colostrum unreliable. 



The essential differences between colostrum and average milk 

 are given below : 



Fairly similar figures are given by other authors. 



The figures for the fat content are very variable, which can 

 probably be accounted for by the difficulty of obtaining an average 

 sample. 



As lactation proceeds changes tend to appear in the composition 

 of the milk. In human milk both the protein and the salts tend 

 to fall, whereas in cows' milk both tend to rise. It is not unlikely 

 that this difference can be accounted for by the fact that cows 



