Materials needed for milk sampling
Materials needed for milk sampling

“That’s really disappointing! What went wrong? How could there be “no growth”? They were all clinical cases! Do we need to re-train the milking staff?”

These are not uncommon questions when discussing milk culture results, and they arise when results don’t seem to match expectations.

I had called the farm to discuss the results from a batch of 16 milk samples that had been sent off to the laboratory for milk cultures.

Common reasons for taking milk culture samples are to find out what is causing the problem, how to treat the clinical cases and how to prevent more cases.

Of the 16 samples, three returned a culture result of Strep uberis, one returned a Staph aureus, and one was reported as “Mixed enteric flora”.

The remaining 11 samples were reported as “No growth”.

Platform on herringbone dairy
Platform on herringbone dairy

Split calving and long lactations have become the norm in much of our industry now, so it was a bit of a surprise when we were contacted recently by a farm in Gippsland that is strictly seasonal, meaning the whole herd is dried-off and milking ceases completely over the dry period until calving starts.

As part of our normal process, a history of Bulk Milk Cell Counts (BMCC) for the last two years was obtained for this herd and then charted with a trend line included.

Leon's cell count chart
Leon's cell count chart

“I culled the 10 highest cell count cows and the cell count didn’t change – not at all!”

Leon* was frustrated – very frustrated!

He milks about 300 cows in Northern Victoria with a spring/autumn split calving system, and I could hear the frustration in his voice.

Leon supplies a processor where the premium payment threshold for Bulk Milk Cell Count (BMCC) is 250,000 cells/ml. The farm has been constantly in and out of premium band for a couple of years now, and nothing he has done has solved the problem.

Culture Results
Culture Results

Paul milks about 600 cows through a large herringbone dairy in Northern Victoria.

The farm’s Bulk Milk Cell Count (BMCC) and number of clinical cases of mastitis had been climbing steadily throughout the wet winter and spring, and it was failing to respond to everything the farm team had tried.

In our initial discussion with Paul, one sentence described the level of frustration and exhaustion for everyone on the farm – “We have hit the wall!!!”

Cows leaving the dairy
Cows leaving the dairy

The last significant in-season drop in the price of milk to suppliers was in 2008, and that doesn’t take a long memory to recall – it is hardly ancient history!

The price drop in 2008 triggered a range of responses, some of which produced significant lessons which shouldn’t be forgotten.

In terms of milk quality and mastitis control there are three lessons that should probably be recalled now to avoid history repeating itself.

Some years ago, Streptococcus agalactiae (Strep ag) was a relatively widespread cause of mastitis in the Australian dairy industry.

It was then commonly known as “Contagious Mastitis”, due to its ability to spread rapidly in a herd.

Because cure rates for treatment of Strep ag are remarkably high, the widespread uptake of antibiotic dry cow therapy into a seasonal milking system nearly eradicated Strep ag from many regions of Australia.

However the trend towards both split and year-round calving, combined with widespread movement of cattle as herds have been sold and disseminated, has seen Strep ag begin to re-appear as a significant cause of mastitis in Australia.

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