Sanitary Studies on Machine Milking

Abstract

In order to investigate the method of hygienic treatment of milking machine, we studied the state of the organisms contaminating the raw milk during milking and the effect of chlorine disinfectant on its contaminating bacteria. The plate counts obtained in the examination of the most of the samples by milking machine were of 105 per ml of milk or higher, whereas those of the milk by hand milking were of 103 per ml of milk or less. The bacterial flora found in the milk and milking machine were the same as found in all the samples.Four types of bacteria were found commonly present thereof. They were Micrococci, Bacilli, Pseudomonas and Flavobacter. Also many Psyclophylic bacteria were found. From these results, it is clear that the contamination with the organisms was attributable to the unhygienic condition at dairy farms, especially, the carelessness in treating milking machine. The bactericidal effects of chlorine water on these contaminating bacteria were examined in vitro. We found that the amount of available chlorine decreased remarkably when a small amount of milk is mixed e. g., the mixture of 1% milk decreased available chlorine by 50%. Based upon these results, the field experiments were conducted at the dairy farms, instructing them the method of washing milking machine, chlorine concentration, etc. The milk produced thereof was a good quality milk from the bacterological point of view.