INVESTIGATION IN MILK PRODUCTION. 
ey ela eeas CARERS 
1. THE FOOD OF MAINTENANCE. 
In all living bodies there is a constant breaking down of 
tissues or wear, caused by every muscular action, just as is 
the case with any piece of machinery. There is also energy 
expended in the action of the muscles and body heat must 
be maintained. The nutrients used by an animal in keeping 
intact the body, that is, in rebuilding the portions worn out 
and in providing the energy and maintaining body heat 
when at rest in stall, is termed the Food of Maintenance or 
Food of Support. The generally accepted feeding standard, 
Wolff’s, gives 18 pounds of dry matter and of nutrients, .7 
of a pound of crude protein, 8 pounds of carbohydrates and 
.1 of a pound of ether extract or fat, as the amount needed 
daily for maintenance per thousand pounds live weight. 
During our earlier feeding experiments it was observed 
that in some instances cows did fairly good work in the 
dairy during a whole winter on only a trifle more feed than 
that prescribed for food of maintenance, indicating that the 
amount fixed by the standard in general use was in excess 
ot the actualrequirements. Sanborn of the New Hampshire 
station reported in 1879 that the steer could be maintained 
on a smaller allowance of hay than is prescribed in the 
standard. Caldwell, of the Cornell Experiment Station, 
New York, reports a trial where four steers gained 1&0 
pounds during a period of 60 days, on practically a main- 
tenance ration. Kuehn, a German investigator, in experi- 
ments extending over several years showed that the mature 
bovine could be maintained on .7 of a pound of protein end 
6.6 pounds of nitrogen free extract, and that whatever was 
fed in excess of this amount, caused gain in weight at therate 
of from 20 to 25 per cent of the amount so in excess. It was 
evident therefore that at thetime when the dairy division of 
the University of Minnesota was established, there had been 
