New York AGRICULTURAL EXPRRIMENT STATION, 15 
believed that this figure represents fairly the digestibility of 
‘ations made up in part of silage and containing a fair propor- 
tion of high-class grains. A widening of the nutritive ratios 
appeared to render rations less digestible, especially the protein. 
The marked changes in protein content and in fat content of 
rations did not produce noticeable changes in the character or 
composition of the milk. In the former test, during 59 days, 
18.4 lbs. of fat was formed in the milk which could not have 
had its source in food fat or food protein and could hardly have 
been drawn from the cow’s body fat as she increased in weight 
do Ibs. in the same time. In the second test Cow 12 in 74 
Gays produced 39 Ibs. of fat similarly: unaccounted for, with 
a body gain of 15 lbs., and Cow 2 in 4 days, 14 lbs. These 
amounts of fat must have come from the carbohydrates in the 
food. 
A lessening of protein supply in the food did not produce a 
corresponding decrease of protein in the milk solids, but caused 
a marked lessening of protein decomposition in the body. Calo- 
-rimeter determinations show that the heat value of urine bears 
no constant relation to its nitrogen content, and also prove that 
the formula used in computing heat energy of urine, Nx5.3438 
Cal., is greatly in error, actual results being from 3 to 4 times 
as large as calculated by this formula. The energy value of 
nutrients as given by Rubner-——protein and carbohydrates each 
4.1 Cal. and fats 9.3 Cal.—appear to be fully high enough for 
herbivora, even when the loss due to escape of unoxidized gases, 
methane chiefly, is not considered. 
Over 40 per ct. of the available energy value of the rations 
was used for maintenance, over 380 per ct. reappeared in the 
milk solids, leaving a balance of from one-fifth to one-fourth of 
the ration. The logical conclusion is that this balance, in part 
at least, sustains the work of milk secretion. 
The immediate effect on milk flow of changes in the composition of 
the ration.—A large number (nearly 1,000) of the individual 
records from a daily herd have been averaged according to 
different relations in the constituents of the food to show the 
