•IS Report of Department of Animal Husbandry of the 



The next table summarizes the results of the entire periods 

 during which exact observations were made, and- expresses 

 numerically the necessary conclusions from these investigations 

 as to the formation of milk fat. 



Relation of Milk Fat to Food Fat and Frotein. 



Fat not 

 accouut- 

 Fat Theoret- ed for Gain In 



Days of digested leal fat Fat in from weight 



expt. from from milk, food fat of cow.* 

 food, protein. and pro- 



tein. 

 Lbs. Lbs. Lbs. Lbs. Lbs. 



Grade Jersey, fat-poor rationt. 59 3.3 17.1 38.8 18.4 33 



Cow 12, fat-poor ration 74 4.8 39.2 83 39 L") 



Cow 2, uormal herd ratiou 4 3.37 2.01 7.23 1.25 — 



Cow 10, fat-rich ration 42 33.1 18.5 45.5 —6.1 18 



* Based upon average of ten days weighings. 

 t From Bui. 132, N. Y. Agl. Expt. Station. 



Some of the figures given are based upon assumptions for 

 which there is little or no justification, but which certainly safe- 

 guard drawing unwarranted conclusions as to the possible pro- 

 duction of milk fat from carbohydrates. 



It is assumed that the digested food fat (ether extract) may 

 be the source of an equivalent quantity of milk fat, but when 

 we consider that ether extract is not wholly fat or oil, and that 

 the glycerides of milk differ widely in kinds and proportions 

 from the fatty compounds of the plant, we see liow unwarranted 

 such an assumption is. Again, the fat factor of protein is taken 

 as 51.4, this being the maximum proportion based upon a theo- 

 retical rearrangement of atoms, of the actual accomplishment 

 of which we have no assurance. For these reasons the excess 

 of milk fat as given, over and above that possibly derived from 

 the food protein and fats, is quite probably considerably more 

 than is stated. But even as the figures stand they are certainly 

 convincing. It is not possible to avoid the conclusion that car- 

 bohydrates serve as at least a partial source of the milk fat. 



With all four cows the ether extract was insufficient for sup- 

 plying the milk fat to the extent of the following daily quan- 

 tities, even allowing the absurd assumption that ether extract 

 is all convertible into milk fat. 



Grade .Jersey, fat-poor ration CO lbs. 



Cow 12, fat-poor ration 1 . 00 lbs. 



Cow 2, ndriual herd ration 90 lbs. 



Cow 10, fat-rich ration 30 lbs. 



