250 The Trials of Milking Machines , 1913. 
Total 
Average 
Trials Old Machine 
Average 5 milkings : 12 cows ; 3 sets of 4 : 
4 cows each machine one milking 
Morning 
Evening 
Morning 
Evening 
3,940 
2,266 
28/4/13. 
27/4/13. 
2,440 
718 
2,800 
1,044 
33,900 
48,938 
17,580 
7,i88 
f J ; 
7,020 
732 
i r ! . . 
12,360 
1,408 
. 8,100 
3,338 
940 
' 410 
26,800 
7,500 
5,500 
3,706 
4,800 
10,400 
6,080 
4,242 ■ 
3,500 
5,100 
100,660 
73,990 
35,100 
23,000 
9,151 
6,727 
11,700 
7,666 
Various possible explanations of these facts may be offered. 
The morning milking began at 5.30 a.m., the evening at 
1.30 p.m. ; there was therefore a difference of 8 hours between 
the milkings. The byres were cleaned up after milking 
ceased ; they were not so clean in the morning as in the 
afternoon. The teats and udders were more liable to be 
contaminated in the morning, these were washed before 
milking. The longer interval of time associated with the 
greater tendency to contamination of the teat orifices 
during the night might tend to an increase in the bacterial 
content of the foremilk. Throughout the trials this was 
supposed to be removed before milking •: it was not very 
efficiently done. The machines themselves had had a longer 
interval of time during which any bacteria still present after 
cleaning could grow in them. The quantity of milk to be 
obtained was greater in the morning, this involved more 
prolonged exposure of the machines to the possibilities of 
contamination in the byre, increased risk of infection from the 
falling off of the teat cups, and in some cases necessitated the 
changing of a can in the middle of the milking of a cow, the 
quantity of milk being too great for the capacity of the vessel. 
All types of machines showed this difference in bacteriological 
content between the morning and evening milkings. 
The keeping quality of the samples . — In order to determine 
the keeping quality of the milks from the different machines, 
composite samples of the milk of the four cows milked by each 
competitor taken after every morning’s and evening’s milking 
were placed in sterile flasks plugged with cotton wool. These 
flasks were kept in a warm room, the temperature of which 
varied from 60° to 72° F. It was not found possible to regulate 
the temperature of this room exactly.; but as the samples 
from each milking stood side by side and were subject to 
