METABOLISM OF THE B VITAMINS 



349 



(a) Thiamine: 0.9-2.4 fig per cent during first few days after parturi- 

 tion, rising to 8.1 fig per cent on tenth day and about 148 fig per cent in 

 mature milk. Free thiamine starts at 1 fig per cent, rising to 5-7 fig per 

 cent, and averaging 37 per cent of the total. 



r 10r100 



-I 

 2 



L .01 



A MOUSE 

 O MAN 



OPYRIDOXINE 



10 MOUSE (>*C/DAY) 100 



1000 



1 MAN (MG/DAY) 10 



100 



VITAMIN REQUIREMENT 



Figure 16. Relationship of the B vitamin requirements of man and the mouse to 

 the levels of B vitamins found in the milk of these species. 



(b) Riboflavin: 19.6 jug per cent on first day of lactation, rising to 

 39.2 fig per cent on the tenth day, with free riboflavin rising more slowly. 

 Mature milk contained a total of about 35-49 fig per cent, with free ribo- 

 flavin composing 43-86 per cent of the total. 



(c) Nicotinic acid: 100 fig per cent on the first day, decreasing slightly 

 from second to fourth day and then rising rapidly to about 250 fig per 

 cent on tenth day. Mature milk contained 175-200 fig per cent. 



