During the 1960’s researchers in the United Kingdom investigated and reported what became known as the first comprehensive plan to control mastitis. This mastitis control plan has been successful since being introduced and is based on the concept that the infection rate of mastitis is directly related to the number of bacteria present on teat skin when the unit is attached to a cow. Teat disinfection is the cornerstone of this mastitis control plan.
The primary function of any teat dip is to flush off the milk film that is left on the teats wherever they were exposed to vacuum during milking. Failure to flush off the milk film will result in a nearly perfect food for bacteria to grow on the teat skin before the cows are milked at the next milking. Once the milk film has been flushed off, the teat dip leaves a germicide on the skin of the teat to kill any present bacteria. Teat disinfection does not affect existing infections.
While it is commonly recommended to cover the teat end and bottom one-third of the teat barrel, this is inadequate. The teat should be completely covered with teat dip. Although teat dip can be sprayed onto teats with a teat sprayer, in most cases, the teat coverage will not be adequate and uses significantly more teat dip than proper dipping. The most common failure in most teat dipping/ spraying programs is not adequately covering teats with a good quality germicidal teat dip immediately after milking.
Because the role of teat dipping is to prevent bacteria colonization on the teat skin as well as the teat canal, it is critical to consistently and properly cover the entire area of the teat that had contact with the milking unit. Teat dip coverage should be monitored on a regular basis by observation of procedures within the parlor and observation of cows outside the parlor in the exit lanes when milk harvest technicians do not know they are being observed.
The best dippers have a reservoir below the dip cup to carry the dip. The reservoir is squeezed and dip comes up to the top of the dipping cup. Dip does not fall back down into the lower reservoir to contaminate the teat dip with any organic material present on the teats. All teat dip containers and containers used to transport dip into the barn or parlor must be kept clean to avoid contamination.
The typical use rates for various application methods are as follows: spraying approximately 20 mL per cow; slosh cup 15 ml; non-return dipper 6 mL to 8 mL; foaming 4 mL to 6 mL; and a Thrifty Dipper 4 mL (when the brushes are properly maintained).
Another important routine observation is how teat dip is moved from storage containers to the parlor. I often see old containers that appear to be contaminated and many do not have valves, so they are open to the air in the parlor. Some dealers install gravity feed or pressurized systems to bring dip into the parlor to make refilling dip cups faster and with significantly reduced potential for contamination. The easier it is to perform a task, the more likely it will be performed correctly more often.
Periodic review of procedures and protocols for both pre- and post dipping programs and the coverage patterns of dip application are essential to the maintenance of acceptable udder health.
David A. Reid, DVM owns and operates Rocky Ridge Dairy Consulting, LLC based in Hazel Green Wisconsin. He has 44 years of experience as a practicing dairy veterinarian and dairy consultant.
Note: This story ran in the March 2018 magazine issue of Dairy Herd Management.