Editor's Note: The following is an excerpt from an article written by Phil Durst, Michigan State University Extension.
"We know that effective pre-dipping is important in reducing the number of new mammary infections caused by environmental bacteria. Milking prep procedures often involve massaging teats after teat dip is applied and forestripping milk. That process removes manure or dirt from the teat and gets the dip to the teat skin, while stimulating the cow.
Several months ago, an owner of a leading milk quality herd told a group that they dipped teats again after forestripping – in effect, a double dip prior to attaching the milking unit. The result for them was a further reduction in herd somatic cell count (SCC) from an average just above 50,000 to just above 40,000. I was surprised at those results given that they consistently do things well and stay on top of mastitis at a level where I assumed any improvement would have only a marginal impact.
Another producer in the group implemented double dipping after that and saw a similar reduction in herd SCC from a similar low starting point. I was still surprised to hear of these results. After all, if you do a good job of pre-dipping, why would there be any benefit to a second pre-dip?
Recently, I was called to visit a herd because the farm was experiencing an increase in SCC. As I watched the milking routine, I saw some deficiencies in teat end cleaning and forestripping. But what surprised me more was that when the milkers left the cow after the first visit, very little dip remained on the teat.
In this case, they applied the pre-dip with a sprayer and only achieved partial coverage. Their massage and forestripping distributed the dip around the teats. But in the process, especially with forestripping, they removed most of the dip from the teat.
I believe that this is the reason that a second dipping offers benefit...
Source: MSU Extension News