Farm biosecurity is everyone's business

10 May, 2017 12:00 PM
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When stock trading becomes a regular practice on dairy farms, it raises the risks of biosecurity.

Biosecurity is everyone's business, according to a dairyfarmer and veterinarian at Kongwak, Gippsland, Victoria.

But while foot-and-mouth disease is the peak focus of much government investment at the moment, there are simple things dairyfarmers can do on farm to reduce disease risk and improve productivity in the milking herd.

That was the message from Dr Andrew Perry, who spent 11 years as a specialist dairy veterinarian in the Kyabram district before moving to Kongwak, in South Gippsland.

"My job was pretty much looking at farm records and providing advice frequently about issues dealing with farm biosecurity," he said.

"That included mastitis, herd pneumonia outbreaks caused from introducing livestock, anthrax and pestivirus - which are risks from heifers mixing with other animal types.

"So biosecurity became an important part of my specific job in Kyabram."

Dr Perry is now working full-time as a dairyfarmer and consulting to the dairy industry on animal health and welfare projects.

"So I've shifted my focus from vet practice to farming and what risks and practicalities that you balance day to day on the farm, particularly when you're putting a dairy herd together," he said.

Andrew and Kerry Perry bought their dairy farm at Kongwak in 2015 - 121 dryland hectares of which 95ha is effective milking area.

They have a herd of 230 Jersey and Friesian-cross cows milking 85,000 kilograms milk solids.

"Although we're 90,000kg so far and aiming for 115,000kg," Dr Perry said in late March this year.

The workforce is the Perrys and a relief milker, working in an 18-swingover herringbone dairy. Average annual rainfall is 939 millimetres.

"When we bought the farm in 2015 it had spent 15 years as a lease block, so it was pretty rundown," Dr Perry said.

"We went in with low equity, so we've been building the herd as we can.

"When stock trading becomes a regular practice on dairy farms, it exponentially raises the risks of biosecurity. But it's a necessary survival strategy for a lot of farms."

Dr Perry has some advice about dealing with the common biosecurity risks on any day on dairy farms.

Cheap and quick test

Dairyfarmers can opt for some cheap and quick tests before introducing cattle to their herd - including for Strep A mastitis and Mycoplasma mastitis, Dr Perry said.

Tasmania's Department of Primary Industries has recognised Mycoplasma mastitis, until now rare on the island, has become more common, is contagious and results in a severe milk production drop. It is also difficult to treat. [http://dpipwe.tas.gov.au/Documents/mycoplasma%20.pdf].

Dairy Australia publications concur that Mycoplasma mastitis is incurable and now found in every dairy region nation-wide [http://www.dairyaustralia.com.au/Standard-Items/Media-Releases/2014-Media-Release-Archive/October/10-15-Mycoplasma-prevention-awareness-and-what-dairy-farmers-need-to-know.aspx]. As well as mastitis, the bacteria cause complications of lameness, pneumonia and calf disease.

"Strep A mastitis is highly contagious but treated easily. Mycoplasma mastitis is incurable and the cow needs to be culled," Dr Perry said.

"It is also extremely hard to get out of a herd once it's affected cows."

He recommends testing a milk sample from the vat; which is easier if buying cows directly from another farm.

"It can be a condition of sale - take a milk sample from the vat, take it in to your vet and they can send it to the laboratory for testing and identifying bugs in the milk," Dr Perry said. "It should cost less than $100 and you should get the result quickly."

Buying untested cows was a risk he thought he would never take himself.

"But the practicality is we went into dairyfarming with low equity, so you buy cheap cows that can put milk into the vat," Dr Perry said. "So we were taking risks we never thought we'd take; fortunately we got away with it."

He cites saleyards as one of the highest risk environments for bringing unwanted diseases on to the farm. "Buying through the saleyard is an extremely high biosecurity risk," Dr Perry said. "You have no knowledge of the origin of the cattle - they could be part of a culling program.

"And there's the risks from co-mingling with other livestock - creating an environment for a nasty respiratory virus to be picked up."

The effects of disease are obvious - production loss, decreased fertility and herd value.

"If you introduce Mycoplasma, there's always a question mark that it's residual in the herd," Dr Perry said. "It instantly devalues your herd.

"It impacts your ability to sell stock as dairy stock, so they become choppers.

"Heifers can contract the bacteria through their mothers' milk - whether that's direct from the udder, herd milk or blue milk.

"Mycoplasma is one of the only bugs that can enter the system through the teat and into the bloodstream.

"It then has a predilection to move to the udder, where it can sit for a couple of years without affecting anything."

It can appear when a heifer has its first calf.

On-farm pathogens risky to herd

Birds, possums and the dairy cat all pose risks to the dairy herd.

For Dr Perry, possums are frequent visitors to the dairy, introducing pathogens.

"So every morning we have to check the dairy is clean of their faeces, particularly in the feed bins where the cows get their ration during milking," he said.

"We like to make the dairy immaculate before milking."

Salmonella was the biggest risk of not eliminating faecal droppings from the grain bins.

"Cows have a fermentation vat in their stomach, they don't have an acidic stomach like us," Dr Perry said.

"If we're feeding them possum droppings, we raise the risk of illness."

In the dairy, using the high-pressure hose to clean away manure was an invitation to spreading disease.

"Pressure hosing in the dairy during milking spreads the bacteria in manure - the bacteria aerolise and you can't see that and if it lands on the teat where it grows, you end up with mastitis," Dr Perry said.

"The more bacteria on the teat, the more it's likely to get into the teat end.

"We use high-pressure hosing in the dairy during milking, because you can't swim in manure - but it's got to be before the teat spray goes on.

"Hopefully, that's eliminating the risk."

Letting cows walk through effluent overflow also increased the risk of mastitis and lameness in the herd.

Diligence was due when feeding vegetable byproducts, particularly in warm weather.

Dr Perry said it was difficult to identify spoilage without getting up close to the feed.

"From the tractor cab, you can't see spoilage," he said.

"But if you put your hand into the vegetables in the feed bunker, you'll find moulds and maggots.

"You think the by-products from processing tomatoes and potato peelings have got good nutritional value, but they were two of the worst offenders in northern Victoria.

"These moulds and mycotoxins, fed to cows, increased poor gut health and led to rapid weight loss.

"It doesn't matter how much you spend on antibiotics, it's not going to be effective. The animal will die."

Dr Perry said the most bacteria-ridden items on the farm were the long milk tubes used to collect colostrum.

"Dairyfarmers forget to clean out the long milk tubes, which allows bacteria to grow in the rotten milk," Dr Perry said.

"The bacterial population causes upset in the calves' gut - immediately there's an upset, salmonella (already present as part of the normal flora) increases in the gut and can knock off animals pretty quickly."

Vibriosis was also a commonly misunderstood risk.

Vibriosis - also known as vibrio - affected bulls but treatment was effective and relatively cheap.

That is why Dr Perry recommends vaccination.

"There's a lot more vibrio than we know of," he said.

"Obtusely, the vaccine for treating vibrio is one of the best around.

"You only have to vaccinate the bulls and very often it cures the bull."

The NSW Department of Primary Industries estimates vibriosis is a major cause of infertility and abortions in dairy and beef cattle, but clinical signs were difficult to identify [http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0009/110043/vibriosis-of-cattle.pdf].

"Bulls carry vibrio because the vector of transmission is the penis," Dr Perry said.

"The bull infects the cow as a low-level infection in the uterus - that leads to the embryo dying."

It could be very frustrating for dairyfarmers, as the cow appeared to be in-calf, then started cycling again.

"It leads to a perpetual circle of low in-calf rates and cows returning to service," he said.

"I recommend minimise and eliminate the risk by giving the bulls the vaccine two months and one month before joining and buy virgin bulls.

"Testing is more expensive than vaccinating as a precaution. And there's too many false negatives."

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