1901.] PUBLIC DOCUMENT — Xo. 33. 21 



with Herd I. Again, should this be the case, why should 

 not the nitrogen increase in the same proportion, instead of 

 actually decreasing, etc. ? 



To summarize briefly, the marked effect of the oil was to 

 produce a quite noticeable increase in the percentage of milk 

 fat when first fed ; this increase gradually' diminished, until 

 at the end of the fifth week it reached the normal.* When 

 the excess oil ration was removed, the milk fat percentage 

 dropped noticeably below the normal. A second effect of 

 the oil ration was to cause a depression in the percentage of 

 nitrogen in the milk, which began to increase only towards 

 the close of the period, and increased to the normal percent- 

 age when the excess oil ceased to be fed. As a result of 

 this experiment, one is led to inquire in what way the oil in 

 the feed caused the temporary increase of fat in the milk. 

 Does the feed oil to any extent enter directly into the milk 

 flit, or does it by sul)stitution cause the body fat to l)e util- 

 ized by the animal in the production of milk fat, as Soxhlet 

 suggests ; or does the feed oil produce a disturbance in the 

 milk glands, causing an increased fat secretion, by utilizing 

 a portion of the material that would otherwise become nitrog- 

 enous matter and nulk sugar? These are questions worthy 

 of further investigation. 



This experiment is rather more decisive in its teachings 

 than many earlier investigations. The question for further 

 investigation is, whether other oils, derived from cotton-seed, 

 corn, etc., act in a similar way to linseed oil. Investigations 

 touching this and other points are now in progress. f 



(d) TiiE Effect of Linseed Oil on Butter Fat. 



Two samples of butter fat Averc taken weekly from each 

 herd, in the ex])eriment above described, and u[)on analyses 

 yielded the following average results : — 



* By normal is meant tlie percentasre produced by Herd I. 



t Tliis experiment was completed during the winter of 1898-99, but lias remained 

 unpublished, owiui,' to the proloni^ed illness of the writer. Since that time Hills 

 (twelfth report, Vermont Experiment Station), Rhodin (Milch Zeitunij 27, pi>. 306- 

 323, 1898), Bartlett (fourteenth report, Maine Experiment Station) and others have 

 published results of a similar nature, to which more extended reference will bo made 

 at another time. 



