NUTRIENT REQUIREMENTS. 103 
Countess gave milk containing 2.5 per cent of butter fat and 
used .208 of available nutrients while Sweet Briar gave milk 
containing twice as much butter fat but did not require 
twice as much protein or other nutrients. The same is the 
case with the other cows. The table also shows that in 
formulating a ration the quality of milk yielded should be 
considered, as well as the quantity. 
Incidentally the table, which is the daily average of 154. 
consecutive days’ work, clearly indicates that other things 
being equal, the richer the milk the more economical is the 
production of butter fat. It has been shown that the richer 
the milk in butter fat the more nutriment is required. In- 
deed it could not be otherwise, for the per cent of solids in 
the milk increases with the increase in butter fat, and the 
rate of increase in energy in rich milk is even greater than 
the increase in solids, because the richer the milk in butter 
fat, the greater the per cent of fat to solids not fat. 
To show the rate of increase in nutrients required for the 
production of a pound of milk of different quality, the records 
of Houston and Countess are employed: 
TABLE XXV.—Showing Difference in Nutrient Requirements for Milk Testing 
High and Low in Butter Fat. 





Per Cent Fat | ; Carbo- | Ether 
in Milk Protein | hydrates | Extract 
NOUS E OMe, ec eeeee cece on neesccseeceseseece ses | Bo nee OSia .26 .019 
OUNCCSS caasesesesecesesstveds: sl ccctencseess | DS | 036 Te Wonk 
ee | | | 
Difference for 30 tenths........... 00. 3.0 | 02% .10 | .007 
| | | 
| | 
Witerenece fOF L COME ...2...scesee:cnnnres | -0007 .0033 | .00023 



By this it is seen that in the production of the rich milk 
the additional nutrient requirements were at the rate of 
.0007 of protein, .0033 of carbohydrates and .00023 of ether 
extract for each .1 per cent increase in per cent of butter fat. 
Taking the nutrients required for a pound of milk test- 
ing 2.5 per cent butter fat as a basis, and the nutrients re- 
quired in addition for each one tenth per cent increase, we 
have the following table giving approximately the nutrients 
required for the production of a pound of milk of a given per 
cent butter fat. 
