50 i^ULLETIN 173. 



of 35 davs each on two rations, one liavins^ a nutritive ratio of 1:6.7 

 and the other 1:12.3 and found that "the yield of milk from the 

 nitrogenous rations was from one-fifth to more than one-third larger 

 than that from the carhonaceous ration. In general the milk was 

 materially richer while the cows were fed the ration rich in protein. 

 4f ^ -^ The composition of the milk solids seemed to be independ- 

 ent of the ration. In general the proportion of fat increased through- 

 out the experiment without regard to what the cows were fed, and no 

 evidence is furnished in support of the notion that by changing the 

 food it is possible to produce more butter-fat without an accompany- 

 ing increased production of the other milk solids." 



Whitcher," after studying the effect of pasture and silage, and of 

 changing the nutritive ratio of the quality of the milk, found very 

 little variation in the per cent of fat and concludes : " I feel warranted 

 in saying that a given animal by heredity is so constituted that she 

 will give a milk of certain average composition ; by judicious or 

 injudicious feeding the amount of milk may be largel}' varied, but 

 the quality of the product will be chiefly determined by the individu- 

 ality of the cow." 



AVood,f in experimenting on the effect of some coarse fodders on 

 quantity and quality of milk during several experimental periods of 

 two weeks each, found " no variation in the quality of the milk that 

 could be attributed to the character of the food." 



Later,:}: he fed three cows for two weeks on a basal ration of silage, 

 clover hay, vetch hay, oats and middlings. Then in three subsequent 

 periods of two weeks each, palm oil, cotton-seed oil, corn oil, oleo oil, 

 cocoanut oil and stearin were fed to different cows at the rate of 12 

 ounces per 1,000 pounds live weight, making a nuti'itive ratio of 1:6.8. 

 The conclusions reached were : " That the first effect of an increase 

 of fat in a cow's ration is to increase the per cent of fat in her milk." 



" That with the continuance of such a ration the tendency is for 

 the milk to return to its normal condition." 



*' That the increase of fat is not due to the oils but to the unnatural 

 character of the ration." 



* New Hampshire Station, Bulletin 9, 1890. 

 f New Hampshire Station, Bulletin 18, 1892. 

 if Same, Bulk-tin '.0, 1891. 



