Dairy farmers are being encouraged to put biosecurity measures in place following recent outbreaks of contagious diseases.
Facial eczema, mycoplasma – an infection caused by bacteria and spread by contact between animals – and strep agalactiae, which causes a severe form of mastitis, are among those diseases recently identified in Australian dairies.
The infectious diseases can affect milk production, and may lead to affected animals being culled.
Dairy Australia animal health and fertility program manager Kathryn Davis said mycoplasma could be hard to diagnose as symptoms varied.
“It causes a range of problems but often shows up as a type of mastitis and doesn’t respond to antibiotics, so it’s almost impossible to treat animals once they’re infected,” Dr Davis said.
“The calves can get middle ear infections, pneumonia, and suffer from arthritis.” Management of the disease is focused on isolation, making sure infected cattle are kept away from other herd animals.
“Milking should be done separately and farmers should give those animals a high standard of care and, if needed, cull animals if they’re not responding,” Dr Davis said.
While few farms have been affected by mycoplasma, the farms where it has been identified were hit hard.
“For the farms affected it’s been a really serious problem, so we’re keen to stop people spreading it unknowingly,” Dr Davis said.
“We’ve seen these outbreaks in every State and every dairy region.
“If anything, it tends to strike larger herds rather than smaller operators.”
Both strep agalactiae and mycoplasma can be detected by requesting a test using a sample from the bulk milk.
Dr Davis said a polymerase chain reaction (PCR) test, which has been available for a few years but was not often used, could identify several different infections.
“The test is done on the herd of origin and gives a guide to whether the herd is likely to have that problem,” she said.
“That lets them understand the disease status of the herd an animal’s coming from.” Dr Davis said knowing the disease status of the herd of origin was the key to preventing outbreaks of infectious diseases.
“When farmers are buying cows direct from another farm, they need to be asking the milk company to send off a sample for testing,” she said.
A biosecurity plan should be in place all the time to keep risk at a minimum but there also needs to be a process to follow when something happens.
Neil Moss, a vet and senior consultant with SBScibus, said there were different levels of understanding around biosecurity in the dairy industry.
“There’s very high awareness from farmers who have had issues, through to farmers who have a minimal awareness,” Dr Moss said.
“All dairyfarmers need to be aware of what can be easily moved around.
“There’s a good awareness of things like Johne’s (bovine Johne’s disease), but the things we need to be thinking about now are some of the mastitis problems.
“One disease that’s had a massive impact in NSW the past five to seven years is Theileria, a tick-borne disease.
“It’s a real challenging one, particularly when moving cattle from the coast inland or inland to the coast.”
Dr Moss said farms needed to manage movement of livestock and trading of cattle and manage visitors to the farm.
Dr Moss said milkers who might work on different properties posed a biosecurity threat.
“Some mastitis can live for a few days on the skin of a hand so milkers should be wearing gloves and it’s advisable that they disinfect.”
Experience teaches lesson
Past experience has taught Tamworth, NSW, dairyfarmer Paul Gibb to be careful of where he buys his cattle.
Mr Gibb, general manager of Realm Agribusiness, has 410 milkers at Willow Lynn.
A serious case of strep agalactiae about five years ago meant the dairy had to begin running three herds – a clean herd, an infected herd and the normal hospital herd.
“We had to have more people in milking and helping drafting,” Mr Gibb said.
He said it took months to verify which cattle had been infected.
“We had to test each individual cow before bringing them back into the herd,” he said.
“The milk from infected cows can’t go in the vat and the treatment had a withholding period so the financial cost of having those cows out of the herd was huge.” Treatment costs, as well as feeding and watering the unproductive cows stacked up.
“It’s not just the cost of loss of production, but treating infected cows until their milk can be used,” he said.
“If they don’t respond to treatment they’re culled, so you could be spending money on treatment and feed and not have a cow at the end of it.”
Source: The Australian Dairy Farmer