At a recent "Regional Milk Seminar" held in Wheeling, West Virginia, the question was asked if it was permissible to milk treated cows with vacuum drawn off of the milk line if a "two-bucket" system was used - the second bucket (pail) serving as an overflow or trap for the first one. Peter Baker, a regional milk specialist with the FDA's Philadelphia office replied that it was the FDA's position that this system was NOT acceptable - no matter how large, or how many milk buckets were used. If treated cows are commingled and "co-milked" with untreated herdmates, vacuum needs to be drawn off of a separate vacuum line installed specifically for that purpose, and using a separate claw and milk hose designated specifically for treated cows*. Ask your equipment dealer if they can install a separate vacuum line if you don't already have one and want to continue milking your treated cows at the same time as their untreated herdmates. You can also contact the Virginia Department of Agriculture and Consumer Services Dairy Inspectors at the regional laboratories for more details about proper installation of this vacuum line. (A separate vacuum line is included as part of a standard installation in most new parlors.) An alternative and arguably much less 'risky' management approach would be to house treated cows separately from their untreated herdmates. While this system is not fool-proof (cows can escape or be placed in the wrong pen), and it may make management of the housing area more difficult, it can significantly reduce the risk of mistakenly milking a treated cow into the bulk tank. The importance of clearly identifying treated cows cannot be stressed enough. Even if electronic systems which can identify treated cows are used, and even if treated cows are housed separately from untreated ones, the possibility for equipment or human error still exists. However, the potential for mistakenly milking a treated cow should be minimized if at least two identification methods are used - ideally one of them being a visual system such as leg bands. A band on each hind leg can provide some insurance against cows that may enter on either side of the parlor, or the possibility of one band being lost. Finally, if leg bands are used for other management purposes in the herd a specific color (such as red) should be reserved only for cows which are not to be milked into the bulk tank - and then no cow should be allowed to be milked into the bulk tank when she has a red band on her leg. While there is no one "right way" to manage treated cows, the preceding suggestions can be used in designing a comprehensive violative residue prevention program. As our herds become larger, and more people are involved in milking (and often with very minimal supervision!), the handling of cows which have been treated with products that require a milk withholding period is a management task that should not be taken lightly.

* According to the FDA, vacuum may be drawn off of the pulsator line (using a two-bucket system) rather than a separate, dedicated vacuum line. However, it would be a good idea to consult your milking equipment specialist about the advisability of doing this because of the potential for affecting vacuum stability.

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