478 EXPERIMENTAL FARMS 



4 GEORGE V., A. 1914 



MILK BACTERIOLOGICAL INVESTIGATIONS. 



During the year the Division conducted an inquiry into the bacterial contents 

 of the milk produced by the Farm herd. It was first necessary to examine the bacterial 

 contents of the natural milk, and also to inquire into the sources of any bacterial 

 contamination with a view to eliminating, as much as possible, impurities of such 

 character. 



The investigations required much time and thought, since, as they progressed 

 further, new phases of work had to be taken up; partly because of the limitation of 

 space in this report, and partly because the experiments will be continued, we only 

 give a brief progress report here and reserve the publication of all details for an 

 exhaustive report to be published later. 



In order to familiarize the manual staff of stable and dairy with the meaning of 

 ' bacteria,' the Director requested the Dominion Botanist to give a series of demonstra- 

 tions and addresses before these men, which were well attended and which resulted in 

 establishing the deeper interest of the men in the various experiments which became 

 necessary. Owing to the interest manifested, the series of addresses proved a real 

 pleasure to the lecturer. 



Because of the scientific nature of such work, some very elementary explanations 

 became necessary, and the nature, development and significance of ' bacteria ' were 

 carefully gone into. 



The work itself may be divided into three main groups: — 



1st. Experiments made with a view to discovering and eliminating sources of 

 bacterial contamination of milk. 



2nd. Quantitative examination of milk before and after certain measures sug- 

 gested for improvement. 



3rd. Comparative quantitative examination of bacterial contents of milk, as 

 produced by hand milking and machine milking. 



SIGNIFICANCE OF BACTERIA IN MILK. 



Before giving an account of the various phases of the work carried on, a few 

 remarks as to the meaning of bacteria in milk may be welcome. 



The bacterial content of milk varies naturally according to the health of the 

 animal from which the milk is obtained, and the treatment and care the milk receives 

 thereafter. For the examination of the bacterial contents, a small quantity of milk 

 is generally sufficient. One cubic centimeter (or 1 ' ec' in its usual form of abbrevia- 

 tion) is commonly examined. This quantity is taken from an average, representative 

 sample by means of an absolutely clean and sterile graduated pipette or glass tube, 

 the capacity of which is accurately measured. This is dipped in the milk and the 

 latter drawn up by gentle suction. According to the size of the pointed mouth of 

 such a pipette one cubic centimeter will ' drop ' from 20 to 25 single drops of milk. 

 Hence, a cubic centimeter is equal to a quantity of from about' 20 to 25 drops of the 

 liquid examined. There are 568-34 cubic centimeters in the imperial pint. 



Bacteria are amongst the smallest organisms of plant life and owing to their 

 purpose in nature are most abundant where dirt and filth accumulate and where the 

 conditions are generally unsanitary. They are principally scavengers of nature and 

 cause the decomposition and final disappearance of any kind of vegetable or animal 

 matter. In this respect they are decidely useful, but no one would, consider them a 

 useful addition to the milk or food consumed. They must in such place be considered 

 as impurities and in the nature of contamination. 



