RESUMO
Recent studies both in the field and in research laboratories demonstrate that pressure changes within a milk machine system can cause bacteria-laden milk droplets to be introduced into the teat during milking. The injection of milk droplets into the teat cistern by pressure differentials across the teat orifice is dependent upon: dissolved gases in the milk, the level of vacuum, the time the teat is exposed to vacuum after the end point of milking, and the resistance of the teat wall to collapse in response to the internal vacuum space within the teat cistern after milking. Recent evidence using scanning electron microscopy, supported by field studies, demonstrates manufacturing problems of teat cup inflations as they relate to bacteriologic contamination in the environment of the teat. A new approach is needed in mastitis control research to include an independent agency for the evaluation of milking machines as they relate to tissue damage and microbial recontamination of the teat orifice.
