Keith Woodford explains how evidence for early arrival of Mycoplasma bovis continues to mount

Graphic from the MPI website.

By Keith Woodford*

A key message from the Ministry of Primary Industries (MPI) has been “generally prolonged or repeated contact with infected animals is required for the disease to be transmitted” (MPI website). Another key message has been that the disease has only been here since the end of 2015.

Bringing those two supposed facts together, it seems surprising that the disease has progressed so quickly in just two years from the so-called index farm in Southland to at least 52 infected farms, with many additional farms still being traced.

Surely, one of the two supposed facts cannot be correct.

Back in May, it was the incongruity between these supposed facts that led Biosecurity Head Roger Smith to tell a Parliamentary Committee that the blow-out rate of infected properties was outside the numbers that MPI had considered likely.  This will also have been an influence in the perspective of four out of 10 Technical Advisory Group (TAG) members in mid-May that eradication was no longer technically feasible, let alone practical.

It is debatable as to which of the two supposed facts is wrong. There is evidence either way. It could even be both.

There is surely one situation where Mycoplasma bovis is highly contagious and that is through infected milk. If we are to eradicate this disease, then farmers must not feed calves with unpasteurised milk from their ‘hospital herd’.

With hindsight, the disease would probably have spread much less if it were not for the feeding of hospital milk.  Almost certainly, this is the fastest way the disease spreads, although looking forward, service bulls are the other big risk. Given the testing the semen companies are now doing, artificial insemination is a much smaller risk.

MPI is saying that all of the infected herds relate to animal movements from the so-called Southland index farm, but the farmers with infected herds that I am talking to are not convinced. Some of them blame over the fence interactions or other transient contact, but the picture there is not clear.

There is another key problem with the theory that all transmission is related to recent animal movements. This problem is that some of the animal movement traces have led to positive tests, but the suspect farms of origin have subsequently tested clean on multiple occasions. It seems therefore that the disease may have already been there on the receival farm from another source. It all gets very confusing.

I find the overall pattern of identified infections more consistent with the notion that it has been in New Zealand for quite some time, with somewhere between 2008 and 2013 being the most plausible explanation.

Each week I get more people ringing me to talk about evidence that the disease was here up to ten years ago. Typically, this is for situations where it is only now that they have put two and two together and said, ‘Aha, this explains things that we could not put our finger on at the time, despite seeking veterinary assistance’.

In some cases, there may be post-event rationalisation, but other cases seem convincing. If there is a common element to them, it is large-framed Holstein-Friesians with imported genetics, including both semen and embryos as possibilities for the original source. The convincing cases include udder blow-out, cold quarter mastitis and arthritis in cows, and lots of calf deaths. Feeding hospital milk to calves also comes into it.

Currently, there are possibilities that the original source could have been another Southland farm, where the farmer was himself an importer of semen (not just a user of imported semen). This farmer had major calf rearing problems around 2008 despite using all accepted protocols. 

This farmer subsequently left the country when he got into major financial stress, and the herd was dispersed around Southland and Canterbury. One of the receival herds is believed to be the same farm that MPI currently regards as the index farm.

Clinical problems in adult cattle have still only been identified on two infected farms out of more than 50 farms known to be infected. Everywhere else the disease has been a sleeper.  It is only when other stress factors come into play that Mycoplasma bovis shows itself to the farmer.  If only a few animals are infected, then the chances of identification or even asymptomatic shedding are low.

One case study I am aware of is where the farm became suspect seven months ago but MPI is still trying to confirm whether or not it is positive. The antibody tests suggest strongly that it is infected, but antibody testing is riddled with false positives.   False negatives can also occur. I have seen antibody lab reports for multiple cows from this farm that have gone from positive on one test to negative on the next, and vice versa.

Multiple PCR tests on this farm have also gone negative, but I have said to that farmer that based on the antibody tests, if MPI keep on testing then they are likely to eventually find a positive. This is also the experience of American vets, who say that in America if you test enough then you will eventually find it.

One of the TAG members has pointed out in a private communication that all of the overseas experience is about finding clinical cases and not sub clinicals. That illustrates how we are in new territory in New Zealand.

Some weeks back, I was criticised by MPI response Director Geoff Gwyn for my report of Gilbert van Reenen’s literature review of cross-species transfer. Gwyn conceded that Mycoplasma bovis could transfer to other species, but he said they were dead-end hosts. As such, the MPI perspective is that there is no risk.

However, MPI itself states in some written materials that it can cause mild infection in sheep and goats, and the research literature suggests this could be a reservoir back to cattle. There are few certainties in this game.

In that earlier article, where I stated that cross-species transmission was proven, I also said there was genuine debate as to the risks of this in the New Zealand situation.  I still hold to that position. I don’t think Geoff Gwyn was correct to be so sure of his facts.

There remains a view within MPI and also amongst some vets that farmer messaging should be kept simple to reduce anxiety. My experience is that farmers want the full story, with all uncertainties out on the table. 

However, I am pleased that at last MPI is showing interest in exploring evidence that it was here prior to the end of 2015 rather than being dismissive thereof. For the first time, I am having productive conversations with MPI.

To date, the counter argument against the need for these investigations has been MPI’s confidence from their genetic clock analyses. But as two geneticists have said to me in recent days, and I have myself been arguing, that conclusion is dodgy.

Accordingly, there is a need to intensively test specific farms in both islands that are linked to historical suspicious disease outbreaks.  Some but not all of these farms can be identified. It only takes one to be confirmed as Mycoplasma bovis and the big picture changes. 


*Keith Woodford was Professor of Farm Management and Agribusiness at Lincoln University for 15 years through to 2015. He is now Principal Consultant at AgriFood Systems Ltd.   His articles are archived at http://keithwoodford.wordpress.com. You can contact him directly here.

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22 Comments

M Bovis is becoming extremely complex to understand and thus making it impossible for farmers to make fully informed decisions. As the new season starts Im seeing calf rearers around us making no real changes to their systems as they simply cant find another way to farm their farms, and yes that means feeding calves "milk from the peno mob".

The talk is several large King country farms are infected as well as a large Auckland farm, all traders of cattle or grazing dairy hfrs. In my eyes its here for good and only a matter of time before it arrives on my door step.

The symptoms you describe are what I'd say are "normal" on all the farms Ive been involved with - Black Mastitis and now Strep Mastitis have become a pretty common problem, as is arthritis but the real question is are they the result of M Bovis or not - difficult to answer??

The feedback from the Waikato positive M Bovis farm is that he saw no symptoms until he put his cows under pressure when he dried them off. Calf rearers who have had it on the other had have been smashed. This evidence appears to be in line with how the M Bovis operates offshore. The difference is that offshore farmers have lived with it for decades and adjusted their production systems to live with it e.g. housed fully feed cows, isolated calf rearing hutches, isolated individual calving to name but a few of the variations.

Either way M Bovis is here to stay and given the huge number of other issues (environment, debt, government and Fonterra) that are going to cost us as farmers and we are going to have to change our production systems to lower our risk & adapt, which makes me think we need to focus on designing our future production systems now rather than all of us sitting back thinking either MPI will stop it or naa its been here for 10 years so no need to worry about it.

Its time an industry think tank of top dogs got together to design a production system for both dairy and beef farmers thats going to help us all get through the next 5-10 years of change thats happening right under our feet without leaving to much blood on the floor.

I don't agree with your last comment Grumpy. I don't believe that it is up to industry 'top dogs' to design a system for beef and dairy. Industry has been proactive in giving information to farmers on actions they can take - well the dairy industry has.
Neither do all countries use isolated calving hutches https://www.youtube.com/watch?v=r2a1UaS_jPs&feature=youtu.be

The spring dairy milk testing programme will be one to watch - will more farms be found? In the South they are testing one month after first pickup - so that will be September for most. Results will be known by November, yet the government is going to review the eradication decision in September????

CO - this is bigger than the dairy industry, there is likely to be large changes required for the beef industry that relies on the dairy beef for their finishing stock.

Not sure of your background but I took the time to look at the link you sent, I suggest that you go to 3.45 and listen carefully and also look at the calving setup - clearly the vets suggesting that all cows be calved individually in a purpose cleaned area - I seriously suggest that you spend some time looking at how the average kiwi cow and calf is handled compared to the video - chalk and cheese - to give you an idea our biggest calving day is approx. 150 calves all of which are calved in 2 mobs which mean that before we get to them theres plenty of time for cross infection from other cows (or wild pigs!) and then of course we have to transport those calves in lots of 20 in a trailer to the calf shed and deal with each one individually for feeding and then they end up in pens of 12 or so, again plenty of chance for cross infection.

Evidence shows calf losses in America and Europe are very high and testing has shown M Bovis present in approx 50% of calves killed in specific research data.

Our milk tests start in August so results in September - I suspect that MPI already know theyve lost the battle - with over 4000 trace farms now to deal with and constant movement of these stock around the country and lack of MPI man power on the ground we are on a hiding to nothing.

It will take a lot of brain power to work out a plan for so each farm to develop new farm production systems so that the losses as a result of M Bovis are minimised. Its also likely to take a lot of extra capital ($) for the dairy industry to build the infrastructure that I think is required to handle the it. The next big issue is then for the dairy beef calf rearers to design rearing systems that stop M Bovis running right through their calves as the evidence clearly shows it does. The next farm down the line (beef finishers) appear to have less risk with M Bovis damage as the animal has survived the 12 week low immune period after birth and they tend to be farmed under a low stress production system (unlike our dairy cows that tend to be stressed 2-5 times a year), however they do risk getting it in their beef herds which will be a problem.

Also dont forget the other issues in front of us that we need to deal with in the near future;

1. Environmental Laws - possibly all dairy farms will need to house cows using a hybrid type grazing system in the near future.

2. Fonterra issue - change is going to have to happen in order for the industry to survive.

3. Climate change - these unusual wet seasons are going to force us into housing cows

4. The huge debt levels the farmer and fonterra carry put the industry in a difficult position if something like m bovis really takes a hold and coupled with a lift in interest rates could mean serious pain.

Hence why I say the "top dogs" (whoever that should be) really need to looking for solutions to move this industry forward. Keith Woodford has already said in past reports that theres been no take up from Dairy NZ in regards to starting research work with composting cow barns, Ive picked up on this system and think its got a future and is a far better system than our typical "herd home or loafing pad" and cheaper than a freestall system, but it needs research which takes time and I believe the industry is at a critical stage where time is of essence.

The difficulty I have is very simply if Ive got to invest in depreciating assets (e.g. cow houses) to continue dairy farming in NZ then Ive got to get a decent return. Given all the above and the past few years of bad seasons and very low payouts its difficult to find any "lead in the pencil" to write the cheque out in order to have the right to continue to farm in NZ.

We are all sitting "treading water" waiting and hoping M Bovis will go away. MPI have given us false hope and so we all sit waiting making no real changes to our Production Systems. If MPI comes out in September and say we gotta live with M Bovis and there will be no further compensation then what..................

"Sink or swim guys, we gotta get ahead of the wave here".

Grumpy -I agree it is much more than just a dairy industry issue. The wet season the north has had meant we had good winters last 3 seasons - in the deep south. Farmers I talk to, by and large, don't believe eradication will happen and so have already been talking to their calf buyers about what they will do in the future. So far their buyers will continue to buy their calves, aren't looking to feed raw milk etc. Some dairy farmers are saying feeding penno milk will be a thing of the past in their operation and more attention to hygiene in their calf sheds. Will consider pasteurising their calf milk. Trucking companies sanitise their trucks before coming on farm when shifting stock between winter graziers and dairy farms etc

From previous posts, I think you are a large herd farmer whereas we are under 500cows with our own runoff for winter grazing and grazing of calves until May, when they go out to graze and return as in calf heifers. Therefore we probably approach this slightly differently because we don't have the numbers you do to consider.
The video was more to show that not all calves overseas are housed in individual hutches. I am aware of calving systems in the UK, as we have friends there who farm around 1000cows - milk year round and not all their cows are calved per the recommendation in that video. But there are some takeouts that NZ farmers can use - especially in regards to hygiene e.g. before entering the calf shed.
I'm not convinced that all the 'powers that be' are on board with housing cows - we lose a very significant marketing advantage if we join the 'housed cow' brigade. Also they are aware of the debt issue and the viability of particularly smaller farms if significant investment had to be made in to animal housing. In UK/Ireland there is a move to farm outdoors more. e.g. Our friends cows are only housed in winter due to the clay soil type, the rest of the year they are outside - we recently stayed on a beef farm in Ireland where the same system was used. I wonder if the fact that our cows aren't housed, is one reason why it has taken so long for m bovis to be found and many perfectly healthy cows killed - that grazing them outdoors is healthier than barn systems. The MOTH has worked with a composting barn system off shore, in the last decade. Some of the takeouts he took from it -Requires expertise in the system, more labour and machinery. Can be difficult to keep temperature warm enough to compost in very cold climates during winter when needing to be turned every day. The system required bedding to be exported off farm as the farm wasn't capable of utilising it all. (There are barn systems in NZ where the need to export effluent arises but it depends on each farms setup) In NZ the cost of bedding materials can be as volatile as payout,and hard to consistently source in some regions.

Regional Council policies and rules in some regions dictate how much and when barn effluent/solids can be spread. Southland rule is the maximum loading rate of nitrogen onto any land area does not exceed 150
kilograms of nitrogen per hectare per year from agricultural effluent or water containing agricultural effluent;
. pg 66 https://www.es.govt.nz/Document%20Library/Plans,%20policies%20and%20stra...(4%20April%202018)%20PDF.pdf

Under the proposed new Southland Water & Land Plan (which is currently being challenged after the submission/hearing process) you can't have more than 120 cattle in one mob (including a feedpad) for wintering. A feed pad/lot is a fenced in or enclosed area that is used for feeding or loafing cattle or deer and all the feed is brought to the animals. The aim of these facilities is to avoid damage to pasture when soils are saturated, and can be located indoors or outdoors. It includes ‘sacrifice paddocks’, wintering pads, stand-off pads, calving pads, loafing pads, and self-feed silage storage facilities.
It does not have more than 120 adult cattle or 250 adult deer on a feed pad/lot longer than three months (or equivalent numbers of young stock)
https://www.es.govt.nz/Document%20Library/Factsheets/Consent%20advice/01...

Climate change - bovis is now got some farmers looking to change their farming system from one where they graze off in winter to that of a self-contained one with reduced cow numbers. Obviously it won't apply to all farms but that is an option for some. This is a potential option for dealing with climate change too - but for some housing cows will be an option. Climate change initiatives may require consideration of the Regional Councils Plans as well.

This could be interesting given BVD is around in NZ herds: It appears that in situations when herds have concurrent problems (other diseases such as Salmonellosis or BVD) or very poor nutrition/environments, Mycoplasma species outbreaks can be severe both in terms of numbers of cows affected and severity of clinical signs. https://dairy.ahdb.org.uk/technical-information/animal-health-welfare/bi...

Compensation - it is only payable if MPI orders destruction of your stock. m bovis has been around for a while and farmers were dealing with it before they knew what they had. Now we know it is here vets will be able to consider bovis in their diagnosis.

Background-Farming 40years. Last approx 20yrs Southland (environmentally sensitive catchment) with 50/50 sharemilkers <500cows. Prior to that North Island sharemilking then owner operator - town milk and seasonal. Southland - milking platform with runoff as above. All grass farming. No PKE.
I'm a glass half full kind of person and believe I am better to control our destiny/business than have someone else do it/tell us what to do, so am inclined to look to be proactive rather than reactive, where I can. As a result I have developed good networks over the years with a variety of agencies to seek information/advice from in order to make decisions.

I wish you well with developing a vision that you want for your business future and the implementation of it to see it become a reality. Don't wait for others to do it - they are already on the back foot. ;-)

You can’t do today’s job with yesterday’s methods and be in business tomorrow.

CO - Great reply thanks which shows the complexity of our issues. Theres is no easy answer apart from running a closed herd (as best u can) and building a system to suit each farm size, soil types, climate, location etc. For me given the rain weve had overnight a freestall barn or composting barn is looking pretty good but Fonterra (& the present Govt. will need to be turned around before I pull out the cheque book! Good luck.

I'm reminded of Upton Sinclair:

It is difficult to get a man to understand something, when his salary depends upon his not understanding it!

That's not perhaps quite the case with the MPI crew, but a sub-clinical variant of it must shurely come into their world-view. It's very hard to resile from the sort of We Know Best statements that you have spotted in their historic pronouncements. But as the evidence, hearsay though it may be at the moment, mounts, they are gonna haveto back-pedal somewhat, accept the wide error bands that seem to exist (timing, whether or not herds or individuals are actually infected, other-species reservoirs, modes of transmission and so on).

In a word, a little Humility....

It's not really MPI - they are just following instructions. It's DairyNZ, Fed Farmers, NZ Beef & Lamb and Fonterra who all supported eradication, and the Government listened with taxpayer dollars.

We taxpayers can only hope the industry bosses were representing their farmer/member views. It would be a bit stupid for us to be forking out all this money in the event that the wider (i.e., so far unaffected) farming community didn't want it!

I don't think that's correct Kate. MPI took the recommendation of their Technical Advisory Group, who voted 6-4 in favour of attempting eradication. Industry groups agreed with that decision.
https://www.radionz.co.nz/news/country/360373/mycoplasma-bovis-four-of-1...

MPI put together a TAG - which subsequently made a recommendation;

file:///C:/Users/user/Downloads/TAG-biographies-May-2018.pdf

MPI then put a Cabinet paper up to the government, including the split in recommendations of the TAG members, plus a lot of other stuff re estimated costs/benefits of the various options.

Cabinet (the government) then consulted industry before making their decision;

Prime Minister Jacinda Ardern and Agriculture Minister Damien O'Connor said the decision to not switch to a management and containment plan was made collectively with farming sector bodies after months of intense analysis to understand the likely impact of M bovis.

https://www.stuff.co.nz/national/politics/104266339/cabinet-is-moving-ah...

To my knowledge, industry has not come out critical of the decision made and neither have they said that they were not consulted prior to the Cabinet decision - neither have they said they would have gone a different way (well, not that I've seen yet). They made the decision jointly with the Government.

MPI are simply acting on a Cabinet directive.

I agree with Kate that it was a joint decision of the Government and industry organisations.
The TAG did not actually provide a recommendation.
Rather, four members said it was not technically feasible, and six said it was technically feasible but may not be practically achievable for a range of reasons including lack of resources, battle fatigue, and flaws in the information they were provided.
The Minister made it clear in preceding weeks that the decision would be made by Government after consultation with industry,
The TAG are actually in a difficult position, as most are overseas , they meet by telephone, and are dependent on the quality of the information that they are provided., They are an advisory group and do not make decisions.
MPI is responsible for the quality of the information that the TAG receives and the TAG has been critical of that quality..
Some industry leaders were supposedly sceptical and claim to have insisted on clear criteria for future re-assessment.
KeithW

Thanks for the clarification Keith.

Thank you once again Keith. I havn't bothered with any of the meetings around the countryside. Why would I when the real juice is on my phone once a week.

Belle do you feel you are getting good support from Beef & Lamb in your situation?

Hi CO. I am thinking you mean 'my situation' as having been alerted by MPI that I had a forward contact animal on my property.
I havnt heard from anybody. Certainly not Beef and Lamb. I know quite a few people in my situation now. We are all just waiting for something. Not sure what that something is ;-) ....I have been asked to bloodtest. But we dont have yards on that block of land. MPI asked if we could borrow a neighbours yards. I just about fell over laughing. I tell that story a bit to elicit a round of laughs.
We all bort stock from 2 properties in the King Country. One of them apparently just shot about 100 head and put them in a pit. The other has been waiting weeks on both blood testing and the test they do on your stock at the works. Trouble is she sold most of the stock that fraternised with the contact stock. What is being tested is a different age group bar one. So I am thinking the likelihood is it will come back negative. Then what. The twenty odd people that bought her stock, do they go ahead and test all of theirs or walk away.
The massive investment required to test all forward contacts I believe is beyond MPI. So it is now July, I heard about mine in March. Why would I encourage MPI to come and test when the test is pretty useless and I send them all to slaughter anyway.
However I know that some of these farms that bought cattle from these two contact farms either have dairy grazers or sell store stock. Out of three that I know none have been contacted yet by MPI.
These 3 farms would be pretty average by King Country standards. They each would carry hundreds and hundreds of cattle. Many different mobs. Blood testing would take a lot of work. A lot of time. I doubt MPI are up to it. Lord help us if it was f&m. It just couldnt be managed. Because from where I am sitting they do not have a handle on mbovis.
As an aside, I attach no blame to these farmers who onsold the stock in question. This is what we do. We trade cattle. And its not something you can stop at the drop of a hat. I also query that MPI understands this. The vast network that cattle follow across nz was grossly underestimated in my view.

The difficulty we all face is the lack of information gathering (MPI and now farmers disposing of sick animal in a hole) regarding the actual effects of an M Bovis infection. Ive sent a letter to MPI asking for an analysis of the symptoms and deaths on each M Bovis positive farm - their reply was that arent collecting that info.

I think that this is a serious flaw and that this type of information would allow us as farmers and MPI as decision makers, to get a much better understanding of the potential damage M Bovis can cause. Without it weve been lulled into a false sense of security e.g. the general feeling out there is that M Bovis doesnt affect Mature animals, is this true or not? Clearly Van Liuens herd got smashed.

Why would someone bury their animals in a hole, as opposed to send them to the works?

Because the farmer suspected they had M Bovis and doesnt want the negative issues of MPI getting involved, or because the works wouldnt take them due poor health.

Thanks, what I feared might be possible reasons. It is a nightmare.

I agree. Sending arthritic or otherwise sick animals to the works risks a fine for animal welfare. It is not allowable to transport these animals. So if an illness does not respond to antibiotics, the animals get shot on farm, and either picked up for pet food or put down the hole. There are no other options.
KeithW

It is my understanding it was young animals so they really had no meat value. This info came through a chain of people. I cant be sure its correct, but everything else I have been told has eventually become mainstream news.

Its clearly evolving into a situation that is far more complex than the capabilities of the industry to cope with. I see some alarming similarities with the PSA incursion that affected kiwifruit in that this is far more widespread than previously thought. Once the banks realised that aspect of the PSA incursion they acted in a pretty ruthless manner in their handling of exposed over leveraged orchadists so farmers in similar positions better watch out.

I have heard that the Guava Moth also affects Kiwifruit. Apparently it was first found in Whangaparaoa, but I know it is has made it as far as Dargaville now. I wonder if it will take out production in Kerikeri.