280 EXPERIMENT STATION EECOED. 



DAIRY FARMING— DAIRYING. 



Experiments with milking machines, X. (). IIofman-Bang {Ber. K, Vet. og 

 Landbohojskoles Lab. Landokonom. Forsog. [Copenhagen], 68 {1910), pp. 79. 

 figs. 3). — The experiments were conducted with the L.-K.-Gillie milking ma- 

 chine on the Ourupgaard dairy farm during the seasons 1907-S and 190.S-9. 

 Four uniform lots of 10 cows and 4 heifers each were used in the first season's 

 experiments, when two of the lots were milked by machine and two by hand 

 during an experimental period of about SJ months. One of the hand-milked 

 lots was stripped by hand after having been machine-milked, while this was 

 not done with the other lot until after 42 days from the beginning of the 

 period when it was deemed necessary to do so on account of the decrease ia 

 the milk yield of the cows. In the second season's experiments 4 lots of 14 

 head each were formed, namely, 2 of aged cows and 2 of heifers ; one of each 

 of these was milked by hand and the other by machine. In this experiment the 

 new Thule teat cup was used, which seemed to render it unnecessary to strip 

 the cows after they had been machine-milked. 



The results of the experiments showed that nearly the same amounts of milk 

 were, in general, obtained by either method of milking. For the aged cows, 

 however, hand milking appeared to give a small increase over machine milking, 

 while the opposite was true for the heifers. The chemical composition of the 

 milk was not affected by the method of milking ado])ted. No special ditli- 

 culties were met with in operating the machine, and the cows stood quietly dur- 

 ing the process of milking. The great difference in the ease of milking different 

 cows and heifers by hand was found to be not nearly so pronounced by machine 

 milking. 



The results obtained indicate that one 'man with two machines (milking 4 

 cows) can do about the same work as three hand-milkers, and can milk 50 to 

 60 cows in 2 to 2^ hours. The bacteriological examinations of the milk drawn 

 by the machine and by hand showed that machine-drawn milk may have a 

 lower bacterial content than that of milk drawn by hand if both the machine 

 and the teats of the cows are kei)t scrupulously clean. Care in keeping the 

 teats clean is especially important from the fact that bacteria in dirt adhering 

 to the teats are likely to be sucked into the milk pail with the air and will 

 tend largely to increase the bacterial content of the milk. 



Comparative experimients with cream separators, N. O. Hofman-Bang and 

 P. y. F. Petersen (Ber. K. Yet. og Landbotiijjskoles Lab. Landokonom. Forsog 

 [Copenhagen], 70 {1910). pp. 125+86, pis. 3, figs. 11, dgms. 6).— A critical study 

 was made of the various factors that influence the separation of cream by cen- 

 trifugal force imder i)ractical creamery conditions. The report gives a full 

 description of the three power separators used, viz, (A) Alexandra, (B) Per- 

 fect-Glgant (patent Knudsen), and (C) Alfa Laval, Al, Model 1910, all of 

 about 4,500 lbs. per hour capacity, with diagrams and illustrations, and de- 

 scribes in detail the various phases of the investigation. 



The average percentages of fat as determined by the GottJieb method in the 

 skim milk for all comparative trials were for separator A, 0.07G, B, 0.066. and 

 C, 0.068. The average percentages of fat for the three skimming temperatures 

 adopted were 0.061 at 75° C, 0.069 at 55°, and 0.076 at 35°. By varying the 

 amount of cream obtained between 7 and 20 per cent it was found that the 

 larger the percentage of cream the better skimming resulted. With 7 per cent 

 of cream there was O.OSS per cent of fat in the skim milk, with l.S per cent, 

 0.068, and with 20 per cent, 0.065. The normal amount of milk run through the 

 separators was about 4,000 Danish pounds, but the amount varied between 

 3,500 and 4,500 lbs., the average results for 3,500 lbs. being 0.067 per cent of 



