By Lisa Whitfield

I have been involved with the milk quality and mastitis scene for a number of years now, and one of the most consistent problems identified on farms struggling with rising cell counts and grading situations is bad teat spraying.

Most farms are doing this very important job already, but are you actually doing a good job? Do you know what a good job looks like?

One of the first clues a farm is not teat spraying particularly well is seen in the results of milk cultures from high cell count cows.

A bacteria called Corynebacterium bovis, which lives on the skin of cows and loves to colonise the teat canal is what we see grow from milk cultures when teat spray application is not effective – either the teat spray is not being applied to everywhere that needs it, or bacteria are able to hide from the teat spray which happens when there is teat end damage. Coryne is readily killed by iodine or chlorhexidine-based teat sprays.

When the teat canal becomes colonised with Coryne, it results in mild to moderate increases in the cow’s cell count – often individual cows will sit between 200,000 cells/ml and 1,000,000 cells/ml.

You might not think those are particularly high cell count cows, but when poor teat spraying is a chronic problem, and 90% of the herd have teats colonised with Coryne, you may well push very close to grading on cell count.

I was initially taught that good teat spray application was achieved if a drop was formed on the end of the teat and this is the level that many farms currently achieve. However, since then, I have learnt that effective teat disinfection means teat spray should cover every part of the teats where the liners touch.

That’s not just the ends of the teats – and it is a lot more coverage than you might expect. The entire barrel of both the front and rear teats should be covered.

The most common area missed is the front of the front teats, however the worst situations are when the teat spray is being applied to the belly, or not applied at all. Automatic teat sprayers have come a long way in the last few years, however, wherever automation is involved in the dairy, it is important that someone actually checks the machines are doing what they are supposed to do.

Problems which arise from automation include weather disturbance (wind blowing the teat spray off course), nozzles pointing in the wrong direction or not firing at all, and the inability to cope with a wide range of udder shapes and sizes.

Another common error is stopping with teat spray part way through the season. This is a major problem as it enables bacteria to proliferate on the teats, and enables more spread from cow to cow. Major pathogens such as Staph aureus thrive in a no-teat spray shed.

Teat spray should be applied after every milking, throughout the season.

Emollient is an important component of teat spray. The disinfectant component of teat spray, whether it’s iodine or chlorhexidine, tends to dry teat skin out if used alone, so the addition of emollient helps to counter this and support healthy teat skin.

Dry teat skin is a common problem – dry areas tend to develop where teat spray is routinely missing, such as the front of the front teats – and these spots will readily harbour bacteria such as Coryne.

On some of the farms struggling with cell count, fixing teat spray issues has dropped the bulk tank SCC by 100,000 cells/ml within a matter of weeks.

Remember, high cell count quarters produce less, and mastitis cases are money down the drain – post-milking teat spray application is one of the critical control points for mastitis – you are already doing this job every day – so make sure you are doing it well.

  • Lisa Whitfield, is a Manawatu production animal veterinarian.