62 REPORT OF DEPARTMENT OF ANIMAL HUSBANDRY OF THB 
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 well selected list of crops grown on 
the farm. 
_W. H. Jorpan, 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 efficiency 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. No 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 
