24 Dikector's Report of the 



5. A reduction, sometimes large, in the percentage of fat in the 

 milk consequent upon the withdrawal from the ration of phjtin 

 and other water-soluble constituents of bran. 



6. A decreased production of butter-fat during the period the 

 washed bran ration was fed, notwithstanding a somewhat increased 

 flow of milk. 



7. The entire cessation of the cestrum period with cow 1 and a 

 temporary disturbance of this period with cow 2. 



8. The foregoing effects were observed chiefly in experiments 1 

 and 3, in which the difference in the phosphorus content of the 

 two rations was brought about by leaching the phytin and other 

 soluble compounds out of the wheat bran. In experiment number 

 2 where the phytin content was small and remained unchanged, 

 similar physiological influences were not sufficiently marked to 

 place much emphasis upon them. 



No definite conclusions were reached as to the compound, or 

 compounds, withdrawn from the bran by washing, which caused 

 these differences. In view of the fact that the principal 

 body leached from the bran was a phosphorus compound believed 

 to be phytin, it was inferred that the physiological effects observed 

 were due to this substance, but it was distinctly stated in Tech- 

 nical Bulletin JSTo. 1 that no definite conclusion was reached. Sub- 

 sequent experimental work conducted by Mr. A. R. Rose corrobo- 

 rated the observations of the former experiments in some particu- 

 lars, but not in others. The details of this later work are given in 

 Technical Bulletin ]^o. 20. 



While there is no doubt but that the leachings from the wheat 

 bran contained substances having marked physiological reactions, 

 we are not yet able to connect these reactions with specific com- 

 pounds. One of our weaknesses in an attack upon this problem 

 is a lack of definite knowledge concerning the exact nature of the 

 phosphorus-bearing compounds in the various feeding stuffs. At 

 the time of the first experiment, it was believed that the main 

 phosphorus-bearing body of wheat bran was phytin. More recent 

 researches indicate that this is not the case. The investigation of 



