370 EXPERIMENT STATION EECOED. 



with a ration of 25 lbs. of alfalfa and 4 lbs. of grain, but in the former case 

 the food cost of the milk was 83 cts. per hundred pounds and of the butter fat 

 18.7 cts. per pouud as compared with 53 cts. per hundred pounds for the milk 

 and 13 cts. per jwund for the butter fat in the latter ration. 



Cows averaging 1,035 lbs. in weight produced milk at a food cost of 53 cts. 

 per hundred povuids and butter fat at 12.9 cts. per pound on a daily ration of 

 23.1 lbs. of alfalfa and 8 lbs. of grain, whereas on a ration of 26.3 lbs. of alfalfa 

 and 4 lbs. of grain they produced milk at So cts. per hundred pounds and butter 

 fat at 11.3 cts. per pound. 



With cows averaging 1,015 lbs. in weight and receiving a daily ration of 17.1 

 lbs. of alfalfa, 9.8 lbs. of grass hay, and 4 lbs. of grain the food cost of 100 lbs. 

 of milk was 47 cts. and of 1 lb. of butter fat 12.4 cts. On a daily ration of 16.0 

 lbs. of alfalfa, 10 lbs. of grass hay, and 8 lbs. of grain the cost was 57 cts. 

 per hundred pounds for the milk and 15 cts. per pound for the butter fat. 



The author concludes from his experiments that the daily yield of milk and 

 of butter fat was greater and the millc flow was maintained better on the larger 

 than on the smaller amount of grain fed with alfalfa, but that the milk and the 

 butter fat were produced cheaper with the smaller grain ration. In these ex- 

 periments 13 lbs. of good alfalfa hay was nearly equal in value to 11 lbs. of 

 grain, as a supplement to a basal ration of 4 lbs. of grain and 12 lbs. of hay. 



Milking machines, W. A. Stocking, Jr., C. J. Mason, and C. L. Reach {Co)i- 

 ncciicul Siorr.s ,St(i. Bui. .',7, pp. 101-138. fif/.s. 10). — Part 1 of this bulletin, by 

 W. A. Stocking, jr., and C. J. Mason, gives the results of studies of the effect 

 of milking machines upon the quality of milk and part 2, by C. L. Beach, studies 

 of the effect upon milk yield. 



Effect ii])Oii quaJity of milk. — In 9 experiments the milking machine was 

 treated in different ways and the bacterial content of the machine-drawn milk 

 was compared with that of hand-drawn milk. * 



In the first experiment the machine was at night simply rinsed by pumping 

 warm water through it and after use in the morning taken apart, scrubbed with 

 hot w^ater and washing powder, and rinsed with clean water. The pails were 

 sterilized by steam. The bacterial content of the machine-drawn milk averaged 

 15.524 per cubic centimeter and of the hand-drawn milk 3,144. 



The machine was next treated as in the first experiment but in addition the 

 rubber tubes and teat cups were kei)t from morning until evening in a 1 : 300 

 solution of a washing powder. The bacterial content of the machine-drawn 

 milk averaged 43.122 per cubic centimeter and of the hand-drawn milk 18,729. 



In the third experiment the tubes and cups were kept in a 2.5 per cent solu- 

 tion of formalin between milkings, other conditions being the same as in the 

 previous experiments. The tubes were made practically sterile by this treat- 

 ment and the rubber w-as not injured. The tin-covered teat cups, however, 

 were somewhat corroded. The average bacterial content of machine-drawn and 

 hand-drawn milk was respectively 20,225 and 23,.329 bacteria per cubic centi- 

 meter. 



In the fourth experiment all parts of the juachine were sterilized by steam. 

 This was found very injurious to the rubber. The average bacterial content of 

 the machine-drawn and hand-drawn milk was respectively 19,984 and 18,172 

 bacteria pe;r cubic centimeter. 



In the fifth and following experiments a new style of connector was used, 

 which admitted air into the teat cups to relieve suction. The tubes and cups 

 were kept in a 10 per cent salt solution between milkings. This treatment 

 did not render the tubes sterile, and the brine itself was found to increase in 

 germ content from day to day. The machine-drawn milk contained on an aver- 

 age 12,962 bacteria per cubic centimeter and the hand-draw'u milk 10,306. 



