62 Report of Department of Animal Husbandry of the 



periods. The evidence presented concerning one point is fairly 

 consistent and is important, viz.: that changes in the quantity 

 of nutrients have greatly more influence on the milk yield than 

 proportionally large changes in the amount of protein. These 

 data offer strong evidence that if the available energy of the 

 ration is sufficient and is kept at a uniform point, there may be 

 quite a wide range in the nutritive ratio without materially 

 affecting the milk flow. This emphasizes the necessity of uni- 

 form feeding and the importance of knowing to what extent 

 changes in the materials of a ration cause changes in the 

 nutrients actively available. The evidence relative to the pro- 

 tein supply at least suggests the practicability of successfully 

 feeding dairy cows from a w^ell selected list of crops grown on 

 the farm. 



W. H. Jordan, Director. 



SUMMARY. 



The data published in this bulletin show the changes in milk 

 production which have immediately followed changes in the 

 composition of the ration fed to cows. The eflieiency of differ- 

 ent rations for sustaining milk production over long periods is 

 not shown. 



Several hundred individual records (981 in all) for limited 

 periods covering different changes in the rations were selected 

 from those kept for a dairy herd during several years. These 

 were grouped in accordance with certain relations which they 

 held to factors of the recognized feeding standards, and aver- 

 ages were made. The average data considered are those which 

 relate to changes in the amount of total digestible organic mat- 

 ter or '' total nutrients," the fuel value, the amount of protein, 

 and the nutritive ratio. Xo rations that would appear in any 

 respect radically deficient were fed. 



TOTAL NUTRIENTS. 



In general, the milk flow increased most or diminished least 

 when the greatest increase of total nutrients was made without 

 regard to moderate changes in protein content. The most rapid 



