436 MISSOURI AGRICULTURAL EXP. STA. RESEARCH BULLETIN NO. 12 



was determined in the manner previously described. Thirty days 

 after calving the blood was tested again. The color of the milk fat 

 was determined at this time also. The color of the blood serum of 

 another Jersey cow was determined at another time twelve hours 

 previous to the time it was judged she would give birth to a calf. The 

 data obtained in the two experiments are given in Table 7. 



TABLE No. 7. RELATION OF BLOOD SEBUM COLOB TO COLOB OF COLOSTRUM 



MILK FAT. 



It is readily seen that another explanation must be sought for 

 the high color of colostrum milk fat, other than an accumulation of 

 carotin in the blood. No doubt a certain amount of storing up of 

 carotin does occur if a cow is dry previous to parturition and the 

 serum is low in color at the time of drying up, it being supposed 

 of course that the food contains a plentiful supply of carotin. The 

 data presented in Table 7, when coupled with the data in Tables 3 

 and 4, show very clearly that under normal conditions the amount 

 of pigment carried by the serum does not exceed a certain maximum 

 point that appears to be practically the same for all cows, regardless 

 of breed. This is not abnormal when it is considered that the carotin 

 of the blood serum is in combination with a protein which no doubt 

 comprises a more or less constant proportion of the blood. 



This result forces us to the same conclusion reached in connection 

 with the study of the physiological relation between food, blood serum 

 and milk fat carotin, namely that other factors, among which may 

 be the composition of the milk, must be taken into consideration in 

 explaining the pigmentation of milk fat. In the case of the high 

 color of colostrum milk, some facts stand out that seem to have a 

 special bearing upon the phenomenon. For instance it is a well-known 

 fact that the milk drawn for the first few days after parturition has 



