Excerpt from Bacteriological Investigations of Milking Machines

It will be observed, from the data presented in Table 2, that all four machines were found capable of producing milk of low contamination. The variations in the counts obtained are not considered sufficient to warrant making any distinction between the different makes, particularly in View of the fact that the ranking according to bacterial counts was not the same with the two media employed. This Is further borne out when the counts from the individual cows are considered with respect to the type of machine. Each machine was found to have the lowest average bacterial count in at least one instance. It is safe to assume that differences in contamination due to the machines tested, should such exist, are quite insignificant with proper treatment, and are obscured by other variable factors inherent in experiments of this-type.

When the results Of machine milking and hand milking are compared, it will be noted that the hand drawn milk showed a somewhat lower contamina tion, the bacterial counts being, in fact, particularly low. 2 We are inclined to attribute this, at least in part, to the fact that the five employees in this test were not only desirous of beating the machine, but also vied with each other in producing the hand-drawn milk of lowest contamination. Furthermore, the adoption of the suction method of washing the machine (see Part III) in prefer ence to the brushing method used in this experiment would undoubtedly have effected some reduction in the contamination of the machine-drawn milk. Fur ther data to be presented in Part IV of this bulletin, in which a comparison of machine and hand-drawn milk is made, support the view that high grade milk may be consistently produced with either method.

When the plate counts on purple-lactose agar and nutrient agar are com pared, it is seen that with machine-drawn milk the official plate count (nutri ent agar, 37 °c., 48 hours) is in all cases lower, with practically no difference in the case of hand-drawn milk. From this it would appear that bacteria capable of growing at blood heat form a larger proportion of the organisms encountered in bland-drawn milk than in milk of correspondingly low grade produced by mac me.

About the Publisher

Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com

This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.