148 INVESTIGATION IN MILK PRODUCTION. 
fat, and less with cows giving milk containing a high per 
cent of butter fat. 
5. The normal net nutriment requirements to a pound 
of milk solids yielded is approximately 2.4 pounds with a 
slight increase with cows yielding milk rich in butter fat and 
less with cows giving milk containing a low per cent of 
butter fat. 
6. When the daily nutriment available for product and 
the products yielded daily are reduced to an approximate 
common value of energy, it is found that it requires about 
1.75 pounds of available nutriment to 1 pound of product; 
that is, of the available nutriment, 43 per cent is expended 
in energy and 57 per cent is returned in the milk solids. 
7. The daily yield of butter fat inexcess of the nutriment 
supply, by virtue of an average daily loss per cow of 2 
pounds in body weight, was .283 of a pound, being a sacri- 
fice of 7 pounds in body weight to 1 pound of butter fat 
yielded in excess of that provided for in the ration. 
8. When the normal working condition of body weight 
is reached, the nutriment required to a pound of butter fat 
and a pound of milk solids remains quite constant for an in- 
definite time under proper management. 
