Are you having trouble with a high thermoduric count?

A thermoduric count of 120 CFU/ml, or less, should be easily achievable, according to Glanbia milk advisor, Jerry Cronin.

Speaking at the Teagasc National Milk Quality Farm Walk, hosted by the Power family in Co. Waterford, Cronin said thermoduric bacteria are always going to be present.

“It’s everywhere. You cannot avoid having it. There is always gong to be a certain amount in the milk,” Cronin said.

While Teagasc report a satisfactory thermoduric bacteria count of less than 500 CFU/ml, Cronin claims a count of 120 CFU/ml, or less, should be easily achievable.

Thermoduric bacteria – which means heat-resistant – are organisms that survive pasteurisation and carry-over into the product, explained Cronin. They can affect the shelf-life and the taste of the product, and also the health of the consumer that will be eating the butter, cheese or other end-product, he added.

Soil and dust are the most prominent sources of thermodurics during the summer period when cows are on grass; while silage, faeces and animal bedding are the most important sources when cows are housed indoors.

Thermodurics can contaminate teat surfaces during periods of both dry and wet weather and are readily transferred to the milk during milking.

Ways to achieve and maintain a low thermoduric count

Cronin advised to have cows’ teats clean and dry before milking, as the teat is the likely route of thermodurics into the milk.

In the milking machine it is important to have the rubberware in good condition.

“Liners need to be changed every 2,000 milkings. Long milk tubes, from the clusters up to the milk-line, have a life-span of about three years.

“Once they go beyond that, they’re going to crack,” Cronin said.

No matter how good your wash routine is and your temperature of water, if you have worn, cracked rubberware it’s going to be nearly impossible to keep it clean, and you’re going to have a high thermoduric count.

Cronin highlighted the importance of a good wash routine inside the milking parlour.

The most important aspect of the wash routine is the pre-rinse, according to Cronin. He advises 14L of clean water per unit. The pre-rinse ensures that the machine is cleaned out of milk residues and will make the detergents work.

“If you have a poor wash routine, thermoduric bacteria will find a home [in the milk machine] and they will grow into huge numbers,” Cronin said.

With inadequate cleaning, thermoduric bacteria in the milk attach to the inside of the rubberware and milk-line forming a biofilm – a brown, waxy film.

This biofilm builds and grows over time, Cronin warned, and the detergent will have no effect whatsoever.

If a biofilm is found in the milk-line, it indicates that the temperature of the hot wash is not hot enough.

“You need to be starting [the hot wash] at 75°,” Cronin said.

The bulk tank may also be a reason for a high thermoduric count, according to Cronin, if it isn’t being washed properly.

With automatic systems, Cronin advised to measure how much detergent is actually going through the machine every two months.

It could be taking up only half the volume that it was set-up for, Cronin said.

You could have a very good TBC (total bacteria count) and then all of a sudden you have a high thermoduric count, Cronin warned. “That can happen; it happens fairly regularly,” he added.

“If you keep the rubberware right; cows’ teats clean and dry; proper detergent; and a proper hot wash, you shouldn’t have an issue with it,” Cronin concluded.

Thermoduric levels in milk can be minimised by:
  • presenting clean cows for milking;
  • replacing cracked rubberware;
  • regular plant hot washes between 70° and 80°;
  • weekly acid descale of milking equipment.