Cluster dipping

Cluster dipping and disinfection

Cluster dipping in dilute sodium hypochlorite after milking mastitic cows has been a standard practice in some herds for many years, particularly in recorder-jar parlours where even the glass jars can be backflushed before the next cow is milked. The regular flushing by hand of cluster units, however,  has become a much more commonplace practice as a means of attempting to lower Somatic Cell Counts (SCCs) to meet increasing milk quality demands from milk buyers.

The practice slows the milking routine and gives milking staff extra tasks to perform but can be an important means of controlling pathogen spread, especially in controlling high cell-counts in problem herds. Infected milk residues from cluster units that are not disinfected can cross-contaminate the following six to eight cows to be milked with the cluster. Peracetic acid disinfectants tend to be recommended for this procedure as they are less likely to damage parlour rubberware.

By marking high SCC cows with leg or tail tapes, or milking them as a separate group, milkers can target those cows most likely to spread mastitis pathogens. The ideal way to flush the cluster unit is to dip them in a bucket of disinfectant solution, two teatcups at a time, so that there is no air pressure build-up in the cluster unit to prevent the solution from entering the liners, but it is important to ensure that the liners do not touch the parlour floor.

At least one manufacturer has produced a system whereby cluster liners are automatically flushed with sanitized water after each cow has been milked.

Mastitic cows should ideally be milked through a separate cluster unit into a dump bucket or dump line, which must be disinfected with hot disinfectant solution after every cow and particularly as part of the cleaning routine at the end of milking.

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