NOTE ON THE COMPOSITION OF 



A FLUID OBTAINED FROM THE 



UDDERS OF VIRGIN HEIFERS 



By HERBERT ERNEST WOODMAN, Pji.D., D.Sc, 

 AND JOHN HAMMOND, M.A. 



{From fJie Institute, for the Study of Animal Nutrition, 

 School of Agriculture, Cambridge Universitg.) 



The secretion of milk by the mammary glands normally follows a period 

 of pregnancy, but numerous cases have been cited in the literature of 

 secretion which takes place in animals that have never borne young. 

 Non-pregnant bitches frequently secrete milk several weeks after 

 oestrus (1), and a secretion, apparently similar to milk, takes place after 

 pseudo-pregnancy in rabbits (2). No quantitative analyses have been 

 made of these secretions to show whether they possess the characteristics 

 of true milk or colostrum. 



The origin and significance of colostrum itself, as distinct from milk, 

 is also in doubt, and its formation has variously been attributed to: 

 (1) The break up of the central cells of the alveolus, or as a result of their 

 initial activities; (2) The filtration of lymphatic secretion through the 

 walls of the alveoli mixing with the milk formed by the cells. Recent 

 work on the proteins of colostrum (3) has shown that although the 

 caseinogen and albumin must be elaborated by the mammary gland, 

 yet the globulin, which is present in large amount in the colostral 

 secretion, is in every respect identical with the globulin of blood serum. 



There also exists the possibility that colostrum results from the 

 partial absorption of the more diffusible milk constituents, the secretion 

 of which has been taking place to a small extent some time previously. 



It was therefore of considerable interest to find, during a study which 

 is being made by one of us (J. H.) of the development of the udder of 

 the cow, that the galactophoroiis sinuses and ducts of virgin heifers of 

 some 1| to 21 years of age contained very frequently a fluid which could 

 often be expressed from the nipples in quite considerable amounts. The 

 object of the present work was to investigate the composition of the 

 secretion and its possible relation to colostrum and to milk. 



It has been suggested by several writers (i) that the mammary gland 



Journ. of Agric. Sci. xn. 7 



