Cow in a hot, dry paddock

Once again, this could be a long, hot summer.

Farms expecting these conditions will now be making plans to help the cows cope with the heat, especially in those regions where temperatures and/or humidity can be extreme.

For those farms wanting more information, or to check their current strategy, Dairy Australia's Cool Cows website ( is a fabulous resource with a large amount of information to assist herds in managing heat stress.

Plus you can register for a service to send you localised weather alerts of high risk periods.

Having a strategy to deal with heat stress is extremely important, however there is also commonly an increase in the risk of mastitis under these conditions - each year we see farms experience a mastitis outbreak during or immediately after a heat event.

Is it possible to reduce that mastitis risk, whilst still managing heat stress effectively?

The two core principles for reducing the risk of mastitis are to minimise the number of bacteria on the teat surface and to maximise & maintain teat end health.

Concentrated groups of cows milling and lying in areas of shade will lead to a large amount of faecal contamination in that area, which leads to a markedly increased risk of contaminating teat skin with dirt and faecal material.

Naturally shade is going to be essential, but to reduce the level of contamination, could you manage the amount of time that cows spend in this area, and/or make the area cleaner?

For example, do the cows need to be there overnight? Do they need to be there at times when the heat is not excessive?

Could you clean the area (e.g. with the grader blade)? Could you position feed & water a short distance away from the shade, so cows will defaecate less often in the actual shade area?

Sprinklers in the dairy yard are a really effective and comparatively cheap source of cooling for cows, but they also increase the risk of wet, dirty teats at cups on.

Could you install a sprinkler controller or timer so that they cycle on and off, using less water and reducing the potential for water to run down onto teats?

There are even reasonably cheap automatic systems with an inbuilt temperature sensor and timers that start the sprinkler cycle once the ambient temperature exceeds a threshold that you can set.

But one of the biggest opportunities to manage the risk of mastitis is what you do about any teat contamination once cows reach the milking platform.

Introducing a wash and dry program for at least the contaminated teats prior to cups on during these hot days will substantially reduce the number of bacteria on the teat skin and consequently the risk of mastitis infections.

In some herds, pre-milking teat disinfection at this time may also be a beneficial option, but only if it is done correctly – use a registered product, get good coverage with the spray, allow 30 seconds contact time to kill the bacteria, and then wipe off with a paper towel.

And naturally, these periods are also when post-milking teat disinfection needs to be as good as it can possibly be – all milking staff should concentrate on achieving as close to 100% coverage of teat skin as possible.

Having sprinklers wetting cows immediately post-milking before teat orifices have closed properly can dramatically increase the risk of new infections - washing off the teat disinfectant and replacing it with contaminated water/dirt is not a good idea!!

So be very careful with sprinklers immediately after cups off.

Optimising teat end health is more of a medium term factor.

Hopefully liners have been changed on time (every 2500 cow milkings for rubber liners), milking machines have been tested and are running well, to help teat condition to be as good as possible. If not, the right corrective action taken now could resolve most teat condition issues quite quickly (about 3 - 4 weeks, and there is a lot more summer to come!).

Take some time to plan your strategy now, and get the appropriate advice where necessary – the potential benefits are significant in a hot summer.


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