4O2 MISSOURI AGRICULTURAL EXP. STA., RESEARCH BULLETIN NO. II 



It was there shown that changing the ration of a Jersey cow from 

 one rich in carotin and xanthophylls to an unpalatable one very poor 

 in these pigments did not result in an immediate lowering of the 

 color of the butter fat, but resulted rather in a gradual reduction in 

 color, extending over a considerable period of time. The animal 

 at the same time usually lost weight. This fact taken in connection 

 with the normal high color of the body fat of Jersey cows which 

 was brought out in the present experiments, gives a clear explana- 

 tion of the entire phenomenon. The pigments of the body fat were 

 being drawn upon, or rather the utilization of the body fat for energy 

 liberated pigments which furnished a partial temporary supply for 

 the milk fat. The milk fat of cows, whose body fat lacked this high 

 color would, therefore, under similar conditions lose color very much 

 faster. The high color of the milk fat of Jersey cows on a nonpig- 

 mented ration is, therefore, due to the fact that their body fat has 

 a normal high yellow color. 



THE PIGMENTS OF THE CORPUS LUTEUM. 



Viewed in the light of the foregoing investigations it is not 

 surprising that Escher l has found that the corpus luteum pigment 

 belongs to the carotin group, thus establishing its identity with the 

 principal milk fat and body fat pigments. In view of the plurality that 

 has been established for both the milk and body fat pigments it 

 became at once important to study the corpus luteum pigment in 

 this connection also. Only a few corpora lutea were available for 

 the study, in fact the ovaries of only six cows at different times were 

 available for examination and in three cases only were well-devel- 

 oped corpora lutea found. Of Jersey Cows No. 21 and No. 25 slaugh- 

 tered at the same time, only Cow No. 25 had a corpus luteum of any 

 development. Jersey Cow No. 8 and a Hereford cow were slaugh- 

 tered at the same time but only the beef bred cow had a well-de- 

 veloped corpus luteum. Cow No. 207 slaughtered at another time 

 had no well-developed corpus luteum but there were the remains 

 of a number of former corpora lutea and one just developing. Hoi- 

 stein Cow No. 221 slaughtered some time later, had a well-developed 

 corpus luteum. 



The investigations of the corpora lutea of the Jersey cows, Nos. 

 21 and 25, were carried out on the combined pigments previous to 

 the discovery of the xanthophyll constituent of butter fat pigment, 

 but the data obtained is nevertheless very instructive. 



1. Loc. cit. 



