DATRYIXG. 



667 



toward heat, acetic acid, and rennet. One hundred cubic centimeters 

 of it contained the following amounts of dry matter: 



Composition of Jluid .srcreiioii prrccditifi colostrum. 



The composition of the fluid colostrum is thus seen to more nearly 

 approach that of milk. Four or five days before parturition this 

 secretion disappears entirely and is replaced by colostrum proi)er. 



True colostrum is described as an opaque, yellow liquid of i)ungent 

 taste. Sometimes it'is of brick-dust or reddish color, due to the pres- 

 ence of blood. Its reaction is not well defined, being sometimes acid, 

 sometimes alkaline, and sometimes amphotere. Churning colostrum 

 for 1^ hours gave no butter, but in a centrifugal separator a yellow 

 butter-like product was obtained. It is curdled by heat, acetic acid, 

 bichlorid of mercury, and rennet. The more nearly its com})osition 

 ai^proached tliat of normal milk the less easily it curdled on heating and 

 the less marked its color became. The following table shows tlie com- 

 position (100 cc.) of the colostrum of a Norman cow 6 days before 

 calving (true colostrum just beginning to form), 4 days before calving, 

 and immediately after calving: 



Composition of colostrum at different stages. 



These figures .show a sudden increase in the amount of albuminoids 

 over that contained in the fluid colostrum already reported (6.77 gra.). 

 This may be due to a diversion to the udder of the nutritive material 

 which up to this time had been sup[)lied to the fetus and its connec- 

 tions. An increase in fat and phosphates and a decrease of soluble 

 albuminoids will also be observed. 



