REPORT OF THE DEPARTMENT OF ANIMAL 



HUSBANDRY. 



PART I. 



I. THE SOURCE OF MILK FAT.* 



W. H. JORDAN AND G. G. JENTER. 



SUMMARY. 



(1) A cow fed during ninety-five days on a ration from which 

 the fats had been nearly all extracted, continued to secrete milk 

 similar to that produced when fed on the same kinds of hay and 

 grain in their normal condition. 



(2) The yield of milk fat during the ninety-five days was 62.9 

 lbs. The food fat eaten during this time was 11.6 lbs., 5.7 lbs. 

 only of which was digested, consequently at least 57.2 lbs. of the 

 milk fat must have had some source other than the food fat. 



(3) The milk fat could not have come from previously stored 

 body fat. This assertion is supported by three considerations: 

 (1) The cow's body could have contained scarcely more than 60 

 lbs. of fat at the beginning of the experiment; (2) she gained 47 

 pounds in body weight during this period of time with no in- 

 crease of body nitrogen, and was judged to be a much fatter cow 

 at the end; (3) the formation of this quantity of milk fat from the 

 body fat would have caused a marked condition of emaciation, 

 which, because of an increase in the body weight would have 

 required the improbable increase in the body of 104 lbs. of water 

 and intestinal contents. 



♦Reprint of Bulletin No. 132. 



