Liz swaps city lights for dairy passion

09 Jun, 2017 07:20 AM
Dairy industry young gun Liz Cork hopes to identify what bacteria cause mastitis in WA dairy herds and also evaluate some new technology which might help with early detection and determining treatment regimes.
Dairy industry young gun Liz Cork hopes to identify what bacteria cause mastitis in WA dairy herds and also evaluate some new technology which might help with early detection and determining treatment regimes.

MANY 22-year-olds head for the bright lights and attractions that city life offers on weekends, but not Liz Cork.

At the end of the working week she trades city living and veterinary science studies at Murdoch University for the relative peace and quiet of a dairy farm near Busselton where she savours the serenity.

Instead of partying with friends or fellow students until early hours of a Saturday or Sunday, she gets up in the early hours those days to milk a herd of almost 500 cows in a 60-stand rotary dairy.

Liz also spends her summer holidays and the shorter breaks between semesters working on the dairy farm run by Kieran Chapman and his father Greg.

This has been her routine for almost four years after answering an advertisement for a temporary farm-hand, turning an initial week of work to help pay university fees into a permanent part-time position.

By default dairying has become Liz’s passion – as well as weekend relaxation – and her farm experience will certainly help with a research project, part of her doctorate of veterinary medicine studies.

Her project may ultimately help the WA dairy industry minimise production volume and profit lost to mastitis.

A broad term for inflammatory udder infections caused by a variety of bacteria affecting milk quality and yield, mastitis is prevalent around calving and is recognised as a major economic drag on the dairy industry.

As well, initial treatment with broad-spectrum antibiotics – most commonly penicillin – significantly increases risk of resistance developing rapidly to make combatting the pathogens which cause mastitis much more difficult.

There is also a chance – remote, but still feasible – of treatment drugs entering the food chain via milk or meat.

In her fourth year studying veterinary medicine, Liz is one of the inaugural Murdoch veterinary medicine doctorate cohort due to graduate in December, 2018.

Her mastitis research project is being supervised by Dr Herbert Rovay, production animal veterinarian and Murdoch lecturer in bovine health and management, who has worked and trained in Canada, the USA and Brazil.

Liz is looking at the sensitivity of mastitis pathogens from cases of clinical and subclinical mastitis on WA dairy farms and attempting to establish specific data on pathogens prevalent in the State.

“Over east there’s been research to establish what pathogens are causing mastitis, but there hasn’t really been anything over here,” Liz said last week at Murdoch, during a study break.

“We really don’t know if it’s going to be the same as over there or whether it is completely different.

“And we don’t know what the resistance, or sensitivity, to antibiotics is over here, whether it (resistance) is progressing any faster, the same, or slower,” she said.

Another part of her project is a real-world evaluation and hopefully validation of the accuracy of three off-the-shelf commercial devices which could help early detection of mastitis and identification of pathogens causing it.

Early detection is critical because one form of mastitis is highly contagious and contact with bacteria through milk splashes, from milkers’ hands or gloves or under the rubbers on teat cups, will quickly spread mastitis through the herd.

Subclinical mastitis also shows no visible symptoms in cow or milk.

Dairy Australia and Western Dairy are particularly interested in the product evaluation aspect of her project and have sponsored her research.

Liz won the Western Dairy 2017 scholarship.

Two of the devices to be tested are hand-held new technology giving almost instantaneous readings of somatic cell count (SCC) from milk samples - somatic cells are udder tissue cells in the milk released along with masses of white blood cells by the cow’s immune system to surround and fight off the bacteria causing mastitis.

A high SCC indicates a potentially sick cow.

Marketed as the Draminski four-quarter mastitis detector, one device with four cups allows a milker to strip individual samples from each quarter of a suspect cow’s udder and test the electrical conductivity of each sample.

Mastitis changes electrolytes in the milk – sodium and chloride ions increase and potassium and lactose decrease – which changes electrical resistance.

A lower reading for milk from one quarter indicates a potential infection, but it cannot identify the cause.

The second device known as an RT10, added to a mobile phone along with a dairy app, effectively turns the phone into an infrared microscope enabling a milk sample on a sterile slide placed in the machine to be assessed visually.

It also provides an SCC estimation.

The Platinum version of the RT10 is also claimed to be able to be used to identify the pathogen causing the mastitis.

The third real-world evaluation is of a 3M Petrifilm product, effectively sample-ready bacteria cultivation plates which cut culture time to 24 hours and can be used on farm.

“If they (devices) work and we can validate the devices then we will be actually able to use them to plan treatment strategies based on the devices being able to identify pathogens,” she said.

Part of the process will be to test their accuracy during milking in working dairies – one of the criticisms of the current Rapid Mastitis Test, also known as the California Mastitis Test, is it requires time-consuming careful measuring of milk sample and a reagent to achieve accurate results.

“There’s only one lot of data we can find from a university over in Canada on the RT10, there’s hardly any research been done on it at all to actually validate it.

“There’s some reviews where farmers say they use it and say that it gives them good results, but you don’t know what they are comparing it to – there’s no research on actual on-farm applications.

“So basically we’ll be getting a sample of milk and we will be using the RT10 Platinum to get a pathogen id (identification), we’ll be patching on the 3M Petrifilm and we will also be patching at Murdoch on agar plates – that’s the traditional method of agar culture and the most accurate method.”

Liz said the laboratory tests at Murdoch would be “our gold standard” sample test to benchmark the devices against.

“(While agar culture is most accurate) it’s also the most expensive and it takes time to get the results which is why farmers don’t use it,” she said.

She said the 3M Petrifilm could cut laboratory test time but could only identify a group of bacteria, not an individual pathogen.

“It’ll tell you if it’s a coliform or E. coli (bacteria which indicate potential faecal contamination and presence of pathogens associated with animal faeces) – it basically can tell you if it’s environmental mastitis.”

Liz said the potential value of the devices was in identifying early if a cow or cows had mastitis – with environmental mastitis and early contagious mastitis the only symptom is a higher than usual SCC.

A cow’s natural instinct to try to hide other symptoms as they developed, further complicated and often delayed detection, she said.

“It’s all part of the herd mentality, they’re just trying to protect themselves for as long as they can and hide every sign of it and then when it is too late they suddenly show the signs.

“Subclinical (mastitis) is one of the ones that cause a really long-term drop in milk production.

“She might not show it immediately but she will have a low yield over a long period – it’s (subclinical mastitis) one of the higher economic impacts on dairying.”

The potential value of the RT10 Platinum was in being able to quickly and accurately identify a pathogen, she said.

“There’s a few different bacteria (that cause mastitis), you can get your staphs (Staph aureus) and your streps (Strep agalactiae) which are quite common, and then there’s the E. Coli and environmental ones.

“Depending on what sort of pathogen you’ve got, then you can change management practice to determine how you can manage it.

“Like if it’s environmental then you can make sure your cows’ (udders) are cleaner, where if it’s (contagious mastitis) you need to make sure you’re cleaning cups between putting cows on and your milkers are wearing gloves – that sort of stuff.

“With some (pathogens) the cows can clear the infection themselves, other ones they are not going to clear them at all.

“Like with staph you find if you treat it the first time and the cow recovers, that’s fine, but a lot of the time it can keep coming back.

“It (bacteria) can whirl itself away and you can keep treating it but it will just whirl itself away again, so you can’t actually get rid of it, so there’s no point in carrying on treatment.

“The cow’s just going to keep on getting it and you are putting more antibiotics into the food chain for no use, whereas streps are killed really easily with antibiotics.

“The sooner you can pick up mastitis and know that the cow’s actually got mastitis (and) the more information you’ve got on the bugs that actually cause the mastitis, you know what antibiotics to treat it with and you don’t have to use as many because she’s not as advanced – the cure is actually quicker.

“The big thing (to overcome) is the delay between finding out she’s got mastitis, sending the culture off to the laboratory and getting the results back – it takes several days.

“In the meantime, if you don’t start a broad-spectrum treatment then she’s going to get worse.

“If you do start a broad-spectrum treatment then you are using more antibiotic than you might actually need to.

“So if you can reduce that time right down – detect it and know what bug it is straight away, then you know immediately whether you need antibiotics in the first place, and you can start treating it more effectively.”

Mal Gill

Mal Gill

is wool and dairy writer for Farm Weekly


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