Animal Health

Is your water just water?

By Rod Dyson

WATER IS a basic resource. On a dairy farm it is used to grow feed, provide drinking water to stock, for washing, cleaning and a myriad of other tasks.

And water is just water, right? Well, yes, but no!

Water sources are many and varied on farms, and each source usually comes with its own particular variations in what it adds to water, including sediments, minerals, organic matter, bacteria, etc.

Three recent cases highlighted what this can mean in a milk quality and mastitis control situation.

All three farms experienced a rise in the number of clinical cases of mastitis, and were finding many cases difficult to treat successfully.

Two of the three farms were well used to dealing with the risk of environmental mastitis, often associated with feed pad use, and responded by upgrading the wash and dry regime at cups on, including the use of a teat scrubber (one farm purchased the teat scrubber specifically for that reason).

The results were disappointing for them — the more they washed and scrubbed, the higher the number of mastitis cases!

The third farm was experiencing a consistently high level of clinical cases that didn’t respond well to treatment.

Our first response on being consulted was to insist on milk cultures from clinical cases on these farms.

Cultures on the first farm revealed E.coli to be the main cause of the clinical cases — perhaps not that unusual. On the second farm, more than 60 per cent of cultures were Serratia, and on the third farm a similar proportion were Nocardia.

If this was a result of general environmental contamination, then there would likely be a range of environmental bacteria appearing in the cultures. And whilst E.coli is not that unusual, Serratia and Nocardia are very uncommon in the most recent survey of Australian mastitis bacteria a few years ago — each was less than two per cent of the samples taken.

Clearly something was happening here, and it was highly likely that there was a “point source” of these bacteria coming into contact with cows’ teats.

The most likely culprit would be the water at the dairy, where it is used to wash udders, teats, cups and milkers’ hands, and sometimes to mix teat disinfectant, all of which come into regular contact with cows’ teats.

You might think that it would then be easy to get a sample of the water and culture it to test for these bacteria, but the real world doesn’t work like that. You might be lucky, but experience has shown that there are many factors that often make this approach unrewarding — it is rare to culture the specific bacteria in this situation.

With the E.coli farm, we used a specialist water quality laboratory in Melbourne to demonstrate high levels of the E.coli that was causing the problem in the water tank at the dairy.

On the Serratia farm, we advised the farm to try ceasing all washing of teats etc., and minimise water use in the dairy. Almost instantly, all cases of mastitis stopped and the bulk milk cell Count dropped back to 50 000 cells/ml.

On the third farm we superchlorinated the water tank at the dairy with swimming pool chlorine and the cases immediately stopped.

While that was interesting, and showed the likely source of the bacteria, that was the easy part.

Every situation is different, and the hard part is trying to define the part of the water supply system that is causing the problem, and then to isolate it, by-pass it, or treat it.

It takes time, effort and a fair bit of thought to work through the various permutations and combinations to arrive at the best answer.

Suffice to say, the first farm has now installed an in-line ultraviolet water steriliser, which while expensive to install, is very cheap to run, and the results have been outstanding. It is easy to use — the system advises the user when the filter is getting blocked, when the UV lamp needs replacing, and is very low maintenance.

The only water source on the second farm is river water, and the only source on the third farm is dam water. On both these farms, the water goes through a series of header and supply tanks before being used at the dairy.

Can we define a specific tank or line being the problem? Can this then be treated or can it be by-passed? Can the water be treated?

River water obviously varies dramatically in quality and sediment throughout the year, while the dam water is always high in sediment and tannins, etc., all of which make consistent, effective treatment on these farms more difficult.

While we have effective “workarounds” in place on both these farms, the final answers are yet to be determined.

Which just goes to show that while water is “the essence of life”, it is rarely completely pure, and sometimes brings unwanted complications.

Rod Dyson is a veterinary surgeon and mastitis adviser at www.dairyfocus.com.au