AGRICULTURAL EXPERIMENT STATION. 31 



Relation of Casein and Albumen to Butter Fat. 

 Results at N. J. Experiment Station. 



Holstein Casein and Albumen : Fat : : 100 : 116 



Ayrshire " " " " 100:108 



Jersey " " " " 100:125 



Guernsey " " " " 100:123 



(2.) Effect of certain conditions upon the relative proportion 

 of milk solids. 



A great deal of discussion is going on at the present time in 

 regard to the effect of certain conditions upon the composition of 

 the milk solids. The question is, Can we increase the casein and 

 diminish the fat, or increase the fat and diminish the casein, in a 

 cow's milk, by changes in her food, or does the relation in quan- 

 tity of the various milk solids depend upon the constitutional 

 characteristics of the animal? Again, does the composition of 

 the milk solids vary with the season or with the duration of the 

 period of lactation? One of the tables just given shows the 

 relation in quantity of the casein and albumen to the butter fat 

 in the case of six cows for the period of two years, this relation 

 being determined by the analysis of the milk during five days in 

 nearly every month of the year. It is plainly seen that the com- 

 position of the milk solids is somewhat variable, that is, that the 

 fat is sometimes more, and sometimes less, in proportion to the 

 casein and albumen. But a very careful study of the figures fails 

 to reveal any fixed relation between these changes and the food 

 of the animals, the season, or the period of lactation. The 

 change from cold weather to warm, from dry food to grass, or 

 from a full yield of milk to the diminished yield of approaching 

 parturition, seems to have no well defined effect upon the propor- 

 tions in which the various ingredients exist in the milk solids. 



Whatever changes occur seem to be due to functional causes 

 that are hidden from ordinary observation. Whether or not radi- 

 cal changes in the food have the effect to increase or decrease the 

 amount of a single ingredient of the milk without affecting other 

 ingredients to a like degree, is still a question in dispute, although 

 all the scientific experience of the past indicates that such is 

 not the case. This Station is about to enter into an investigation 

 with a view to studying this point. 



(3.) The effect of an advance in the period of lactation. The 

 general effect of an advance in the period of lactation seems to be to 

 increase the solid matter in the milk. It is especially true that 



