Dec 1,1925 
The Maintenance Requirement of Dry Cows 
1071 
in Period I a loss of protein occurred. The ration fed in Period III 
was a duplication of that fed in Period I. In each there was a small 
gain of energy, differently distributed, however, between protein and 
fat. There would seem to be two plausible explanations for this 
difference—the influence of previous feeding (a supermaintenance 
ration) on Period III, or the refusal of considerable quantities of feed 
in Period I. The writers are inclined to give the greater weight to 
the latter possibility. 
In the lower half of this table appears an item “error.” In effect, 
this represents the difference between the computed and the observed 
heat measurements. If this error is assigned to the metabolizable 
energy it represents but a small percentage of the total. If it were 
included in the heat production its effect would be slightly increased 
but would still be relatively small. On the other hand, if it were 
considered as a part of the energy equivalent of the body gain it 
becomes a major factor materially affecting subsequent computations. 
It is probable, however, that this item of error is a composite of a 
number of components of various origins. However, taking into 
account the painstaking attention to detail and the minute checking 
of the individual measurements in connection with the operation of 
the respiration calorimeter, and, on the other hand, the assumption 
that the dry matter gained or lost by the body consists of protein 
and fat alone, and the influence of the loss on air drying the feces on 
the value determined for the metabolizable energy, it would seem 
that the observed heat emission must be the most accurate. There¬ 
fore it is considered as the reference base in the subsequent treatment 
of the experimental data. 
In the case of cow 886 there were also two periods (I and II) on a 
maintenance ration, and one period (III) on supermaintenance. In 
general, the results are similar to those obtained with cow 885. 
There is a better agreement between Periods I and III, but the 
“error” is considerably greater in the latter period. Judging from 
the appearance of the two animals, and comparing their individual 
reaction to the imposed experimental conditions, we should expect cow 
886 to make the more efficient use of her feed. That this was actually 
the case is shown by a comparison of the experimental data for the 
two animals. 
In 1921, cow 885, which had been bred immediately following her 
last experimental period in 1920, apparently was with calf and was so 
reported by the barn attendants. However, prior to the beginning 
of the next experimental period, she was found to be farrow. While 
her weight had increased since the preceding year, Table II shows the 
gain to have been small in relation to the feed received. Yet she 
appeared to be fat. She was extremely restless. Her neck became 
noticeably thick, as sometimes occurs in cows which have become 
barren. Examination by a veterinarian failed to reveal definite 
functional disorder. It was therefore decided to carry her along 
in experiment 22IE. The results obtained with this oow in the 
maintenance period (II) are markedly unlike those obtained in the 
corresponding period of experiment 22ID. No definite reason is 
apparent other than error due to the refusal of feed during all 
experimental periods, which, of course, renders doubtful the signifi¬ 
cance of the data obtained with the respiration calorimeter. This 
