How Effective is Teat Disinfection?
Under Australian conditions, virtually all mastitis infections enter the udder through the teat end via the teat canal.
The teat canal is a wonderful structure that is constantly working hard to prevent bacteria from entering the udder. If it is either overwhelmed by large numbers of bacteria, or it is damaged and can’t do its job properly, then the cow is at a much greater risk of becoming infected.
Routine post-milking teat disinfection has been, and still is, the single most effective component of hygienic milking programs used in Australia.
How effective is teat disinfection?
During milking, bacteria from an infected cow may be found on the teatcup liners and transferred to the teat skin of the next 5-6 cows that are milked with that unit.
Once on the teat skin, they multiply (especially where there are sores or other lesions on the teat skin), and so increase the risk of the quarter becoming infected via the teat canal.
Post-milking teat disinfection aims to:
maintain healthy skin; and
reduce the number of bacteria on the areas of teat skin that have come into contact with the teatcup liner during milking and able to gain access to the teat orifice. Many field experiments have shown that effective post-milking teat disinfection lowers new infection rates of the cow-associated mastitis bacteria by 50% or more, and recent work, especially in New Zealand, has demonstrated a similar reduction in new infection rates with the environmental bacteria Strep uberis which is now so common in Australia.
There is no benefit from disinfecting any part of the udder surface apart from the teat skin. It is, however, important that the entire teat barrel (everywhere the liner has touched) is disinfected and not just the teat end.
All the benefits of correct product selection, preparation and handling are lost if the teat disinfectant does not reach the teat skin, and the teat disinfectant cannot have any effect on areas of skin that it does not contact.
Routine post-milking teat disinfection has been, and still is, the single most effective component of hygienic milking programs used in Australia
Getting a return on the investment
The majority of Australian dairy farmers use a spray to apply post-milking teat disinfection. Spraying generally requires an application of about 20ml per cow at each milking to achieve good coverage of all the teats, and at current costs this commonly works out to somewhere about 2½ - 3 cents per cow per milking.
For a 305 day lactation in a year, this means a cost of about $15 - 18 per cow per year for twice-a-day milking. Naturally the cost will increase by 50% for any period of three-times-a-day milking.
The return on investment comes from the reduction in new infection rates – the pay off comes from reduced cell counts, less clinical cases, and the knowledge that teat disinfection is a major part of the farm’s risk management for mastitis.
Having invested in the purchase and preparation of the teat disinfectant, the return on the investment is then highly dependant on the actual application of the product to the cows’ teats.
The maximum return on the investment will come from the cows regularly receiving good coverage of the whole teat surface of all four teats at every milking.
Quite often the difference between good coverage and poor coverage may be only a matter of a second or two. To find out how long it takes your spray system to deliver 20ml, spray into an empty syringe or container and note the time taken to achieve 20ml – this is how long you should be taking with each cow.
The other key factor is the spray technique. Each dairy and spray system is slightly different – a little time spent during one milking on exploring techniques and spray angles that achieve good coverage will increase the return on investment at no extra cost in time or product!
You’ve spent the money on the spray system and on your teat disinfection product – it is the coverage of the teats that will determine the return on that investment!
Tips on improving teat spraying efficiency
Good teat coverage is important. It requires careful operators with good equipment and safe facilities. Spray efficiency can be improved by:
Choosing equipment that will spray an even cover of fine droplets to about 10 cm diameter when sprayed vertically from about 10 cm distance. Hollow or “doughnut” patterns are not satisfactory.
Checking the spray pattern regularly by spraying onto a piece of paper.
Arranging work routines to avoid boredom.
Encouraging milking staff to regularly assess their own and each other’s teat coverage.
Simple checks:
Examining individual teats of several cows to determine if all sides of the teat barrel are being covered. Wrapping a paper towel around the barrel, then carefully removing and examining it, can assist this procedure.
Checking that at least 20 mL of prepared teat disinfectant is being used per cow per milking. This involves measuring the total amount of teat disinfectant used over two milkings and dividing this number by the total number of cows milked at both milkings.
Calculating the time in seconds that is needed to apply the correct amount of disinfectant solution. This can be done, for example, by counting the number of seconds required to fill an empty 20 mL syringe barrel with the spray. This can then be compared with the actual time that operators take to spray each cow.
Regular review of teat disinfection efficiency with an adviser can also add to staff training and awareness about the importance of this routine activity in mastitis control.
Choosing and reviewing your teat disinfectant
Teat disinfectant helps keep your cows’ teat skin healthy and reduces the number of bacteria likely to cause mastitis. It is important to choose the product you use carefully.
Don’t make a snap decision to change at the moment you purchase a new drum.
Factors to consider are:
Effectiveness: The dairy industry relies on the Australian Pesticides and Veterinary Medicines Authority’s (APVMA) registration process to ensure that all products are effective in Australian dairying conditions. However, some may be better suited to your particular situation.
Ready-to-Use (RTU) formulations: Ready-to-use formulations have become increasingly popular on Australian farms. They remove the daily task of having to mix a product on the farm, and they remove the risk that poor quality water used to mix a product on the farm may reduce the effectiveness of the product.
Suitability given your farm water quality: Water that’s hard, alkaline or contains chlorine may reduce the effectiveness of different active ingredients in teat disinfectants and may form solids in the solution, which block spray equipment. Testing your water enables you and your adviser to work out which teat disinfectant is most compatible with the water quality you’re using.
Occupational health issues: Skin reactions on the hands of milking staff may be the result of an allergic response to a product. It may also result from heavy exposure due to faulty settings on spray equipment or poor operator technique. Assess how the disinfectant is being used and whether the type of disinfectant should be changed if any staff member has an adverse reaction. A review is appropriate when new staff begin milking.
Teat skin reactions: Teats should be regularly checked to ensure the teat skin is supple and in good condition. It is important to closely monitor changes when a new product is used.
Visibility: You can more easily assess whether you achieve good teat coverage if you use products which are visible on the teat skin.
Price: Teat disinfectant products vary considerably in price. To compare it’s helpful to calculate the cost per cow per milking. To get good coverage Countdown recommends using 20mLs of solution per cow per milking.
Shelf life: Ensure that the quantity purchased – in either concentrate or ready-to-use form – will be finished prior to the expiry date specified on the label.
Field-testing of ready-to-use products in Australia has shown good stability on farms, provided they are stored according to label directions (under 30 degrees Celsius, out of direct sun and in the original closed container) and used within their shelf life. There is limited field experience with storage containers of large volumes (over 1000 litres).
Stability of iodine disinfectants may be reduced if there is a large volume of air in a container, even if it is sealed
By Countdown 2020 - Last updated 16 November 2012
