Head Shepherd
Mark Ferguson from neXtgen Agri brings you the latest in livestock, genetics, innovation and technology. We focus on sheep and beef farming in Australia and New Zealand and the people doing great things in those industries.
Head Shepherd
Managing Triple Drench Resistance in Cattle
As you may have heard in the media recently, triple drench resistance in cattle is quickly becoming an issue for New Zealand farmers.
This week on the podcast, we are joined by Dave Leathwick and Christian Sauerman from AgResearch. They share how they came across the issue, why it has occurred and what producers can do to mitigate the risks of developing triple drench resistance.
Dave and Christian are both ‘accidental parasitologists’, with Dave initially studying entomology, while Christian was focused on biology and zoology. However, both have now been working with parasites for a combined 51 years!
Dave explains that drench resistance has been a long-standing issue: “The national survey that was done on cattle in 2004/2005 - virtually every farm in New Zealand had drench resistance to at least one active - and it just made no difference. Nobody paid any attention.” Now, 20 years later, the issue is far worse.
The research pair point out that they weren’t looking for evidence of triple drench resistance and it only came to their attention when a few farmers had issues with calves not performing well. FEC tests showed alarmingly high worm numbers, considering the animals had been drenched just three weeks prior, and tipped them off to the extent of the problem.
Christian highlights the signs and symptoms that cattle will show and also what producers can do to negate the risks of triple drench resistance. But you’ll have to tune in for that!
Head Shepherd is brought to you by neXtgen Agri International Limited. We help livestock farmers get the most out of the genetics they farm with. Get in touch with us if you would like to hear more about how we can help you do what you do best: info@nextgenagri.com.
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As mentioned, this week's a bit different. We've got two guests on. We don't do that very often, but it's great to have a couple of people on. Welcome Christian and welcome Dave.
Speaker 2:Afternoon.
Speaker 1:Hi Mark. So we're talking drench resistance in cattle today, which is not something that we hear a lot mentioned, but before we get into the detail, it would be good to hear about your backgrounds. We might start with you, dave. You're a principal scientist at AgResearch, just yeah, I guess how you ended up looking at parasites in cattle would be good to hear.
Speaker 2:Well, it was totally unplanned. I went to Canterbury University with the intention of being an entomologist and working on insects and I was the last ever graduate from Lincoln College before it became a university which I'm immensely proud of and I tell everyone at every opportunity. So I came out as an entomologist and immediately got a job modeling drug resistance in parasites of sheep and I moved up to Palmerston North in 1988, intending to stay two years. So 36 years later, I'm still sort of here, Not quite sure how that happened, but it did, and I've spent all of that time focused almost entirely on drug resistance and parasites in sheep, cattle, deer, horses, goats pretty much Excellent.
Speaker 1:Excellent, christian, we'll head to you. Yours is a bit of a story of chance and how you ended up. Both of you are accidental parasitologists, it seems.
Speaker 3:Yeah, so similar to Dave, I am a biologist or zoologist by trade and worked for the cosmetic industry for a while but wanted to get out of there and it's a long story and a lot of chances that just came my way. So I ended up with Bill Pomeroy and Dave Lefric for a PhD. That was 15, 16 years ago now and that was actually based on the last national survey the team did on drench resistance in cattle. So I was looking at coperia in cattle explicitly during my PhD and because Dave paid for my PhD, he said well, once you're finished I want some sort of return of investment from you, so you stay here in New Zealand for at least three years and work for me. For me that was great. You know you do a PhD and more or less have a guaranteed postdoc afterwards, and that postdoc turned into a permanent position. So I joined egg research 10 years ago and now work permanently as a scientist, as a parasitologist, in the parasitology team.
Speaker 1:Excellent, great. So we spent a fair bit of time talking about drenthrosis in sheep and we've seen what seems like a rapid rise. I know that you'll be suggesting otherwise that it's been coming at us for a long time, but I guess all of a sudden people have realised that a lot of the chemicals aren't working as well as they used to. But in cattle, yeah, we don't hear a lot about it.
Speaker 2:so it would be good to maybe start high level Dave as to sort of over your career, what you're sort of seeing creeping up on all species. Yeah, it's interesting because you talk to people about these things and they don't hear you and they think it won't happen to me. The great analogy is blokes getting a prostate test every year for prostate cancer and many, many people don't test because they know it's not going to happen to them until it does. And so drench resistance is very much the same.
Speaker 2:It's always been considered that it was a goat sheep problem and cattle farmers even today be very few that would test their drenches or even thought about testing their drenches. But in reality, the national survey that was done in cattle in 2004-5, virtually every farm in New Zealand had drench resistance in Cooperia to at least one active and it just made no difference. Nobody paid any attention and you know it was one of those wonderful things that just keep going and nothing will go wrong and it's all good. But the last couple of years and things have changed and that you know. The reason we're talking to you today is because we're now starting to see quite in. It's hard to guess, but it's not uncommon now for triple resistance in Kuperia and to a lesser extent in Ostertagia and we're seeing it in cattle systems all over the country.
Speaker 1:Yeah right, Before we delve further into that, we probably should have started at a higher level in terms of what parasites we tend to be. What are the main lurgies we're dealing with? I don't know which of you want to tackle that, but obviously you mentioned capybara and nostatagia. Is there others that are causing production losses in cattle?
Speaker 2:Well, Christian's the cattle expert, so I'm going to pass that ball to him.
Speaker 1:Beautiful.
Speaker 3:Yeah, I think when it comes to cattle, or when it comes to animals, to livestock, it's always young animals that normally suffer the most from parasites, and in young cattle it's definitely coperia in the first year that is dominant and in the second year it's probably switching to ostetagia.
Speaker 3:So those two parasites are very important for the dairy industry and the beef industry because they normally tend to limit the growth rates in the first two years. And so when I started my phd, it was relatively simple to get rid of Ostatagia at that stage and I could focus on Copiria in my calves because Levimizol was still working, one of the drugs against Ostatagia, so I could clean my calves and have pure infection with coperia. And it is scary looking back to, you know, in my life that short period of time where we came from yeah, we could still somehow control these parasites to now a stage where we might not be able to control them with drugs. And so we have to switch, I think, in our mindset and our parasite management strategy in the farming industry from that heavy reliance on if we have a parasite problem we just use a drench gun to a more integrated approach and think about farm systems-wide how do we manage parasites on the farm?
Speaker 1:Yeah, and I often talk about it from the concept. I think certainly me growing up and a lot of farmers I talk to you kind of have this theory that you're out there to wage a war on worms to sort of wipe them out, whereas the reality is just managing a worm population. You're never going to get rid of them. So it's kind of getting out of that mindset that you're killing everything to a mindset that you're managing the population is key to winning. So older cattle, so anything older than two years, normally internal parasites, not an issue, or is that not true?
Speaker 2:an issue, or is that not true? From a practical viewpoint, that's sort of right, unless something else goes wrong. The dominant parasite in those older cattle tends to be a trichostrongylus, a trichaxia we would call it, and it can be pathogenic. But on the whole, once animals get past about 18 months of age, they generally don't benefit much from drenching, unless something else goes wrong. You know, and there'll be parts of New Zealand today who will be candidates for issues because they haven't got any grass yeah, if you can't feed your animals, they're gonna. Everything else is going to go wrong as well.
Speaker 1:So uh, yeah, yeah, no, for sure, the. So yeah, the. I guess the reason we are talking today is because you've now discovered on, well, the report on farmers work. They said four farm studies that have found triple drench resistance in in cattle. What's? Uh? So it's obviously the live msi was the last one working. It's now. It's now let the team down, so the, the triples are not working. Is that where we're at?
Speaker 3:yeah, that's where we are at um, so we still have a class left in in cattle which is all wicks monopental yeah but that lifetime is of course. It goes down the same route as everything else, so it's only limited lifespan we still have left. And yeah, it's hard to see how we can continue with the farming industry when we think about high productive systems which are mainly based on monocultures, heavily grazing limited stock classes of animals in a high productive environment, with a total reliance on informatic treatments to manage parasites.
Speaker 2:Yeah. So the thing that we probably need to point out there is the farms that we reported on. We never went and looked. I mean, that was no survey, they just dropped into our lap. They just came to us through conversations with vets and farmers. And there's quite a few vets out there today who are quite active. And so there was one vet I know in Northland. He's got seven confirmed cases and there will be vets all around the North Island who will have one or two. So you asked the question how prevalent is it? The answer is we don't know, but it's not that hard to find. If I had to go and find one, how long would it take me to find a triple resistance and cattle? A few days probably would be about that. Would you know? A few phone calls and I could find some.
Speaker 1:So, yeah, so it's more, probably more common than what you would think, and it might be more common than what you would like yeah it's the best answer we can give, I think so, when you're on the phone ringing those people up, what are the sort of questions that you'd be asking, as in, what are the signs that the trenches are failing or that, yeah, not working as well as they used to?
Speaker 2:We. I think so in all the cases that we dealt with it was the vet that called us, not us that called the vet. So we weren't out there looking and I think every case so far has been has come from the farmer who's seen clinical disease. So the farmer sees animals scouring, not growing. They look awful. Typical signs of cuparia are runny bums, sunken gut, you know, looking really bad, and so they call the vet. The vet comes in, starts looking for things. Hey presto, it's got a really high egg count and it's full of worms.
Speaker 2:Yeah, when were they last d it's full of worms. Yeah, when were they last drenched? Three weeks ago, ah, okay, problems, problem, yeah, yeah, so that's how, and that's somewhat different to the sheep. It's a bit interesting because it's slightly different to the sheep situation. A lot of drench resistance in sheep is found because the vet harasses the farmer into doing a test yeah, whereas in this case, with these cases, that's not the case. Almost every case has come from the farmer calling the vet I've got a problem, come and fix it.
Speaker 1:Is that because that's at the bottom of the cliff? If you did a test earlier, like if you just went out to any random, you could, like you might, identify before it was here at the bottom of the cliff.
Speaker 2:Yeah, there would be some truth in that, I think. You know, if you don't look, you haven't got a problem.
Speaker 1:That's the best way not to get COVID you just don't test.
Speaker 2:Yeah, that's right. I've got friends who have never had COVID.
Speaker 1:Yeah, I think Donald Trump has had this.
Speaker 2:Yeah, everyone had this yeah.
Speaker 1:Yeah, best way not to get. Well, in Australia it was Yarny's, he just didn't test for it, so it's much easier not to have it. Yeah, and I'm just trying to get my head around how it's developed. I mean, I know how drench resistance developed, but you would think that the adult cattle that aren't affected by those couple of parasites would be fantastic refugia, but that's obviously somehow not working, as in there's still pressure on drenches within those young cattle and do those populations just not establish at all in older cattle and therefore all of the Ostertagia and Caperia are in young cattle and that's why you sort of don't end up with refugia or what's going on on that front.
Speaker 2:That's Christian's. He knows the answer to that question.
Speaker 1:Yeah all right good.
Speaker 3:Yeah, I think the cattle industry is slightly different to the sheep industry and what I see with the cattle industry is that we have very specialized farming systems where we have farming operations and the farm buys in a lot of young stock, raises them and then sells them or raises them for the dairy industry. So you have monocultures of the same stock class, very young animals, and you don't have any other species or stock class grazing those systems. And that is just what we call a recipe for disaster, because you have those young animals which have a lot of parasites because they don't have a fully developed immune response yet, and over over time, especially if you fail to treat them effectively, they start contaminating the farm, they load the farm with parasites.
Speaker 1:so it's an accumulating problem yeah, I know cool, that makes sense and so if I did march around some adult cattle on that land and that would be like we could reverse this problem with the same way would attack it in shape or not I wouldn't say reverse, but it might help.
Speaker 3:It will definitely help if you have an older stock class in there. Um, if you mix it with a totally different species like sheep, that would be the preferable option. Yeah, cool cool.
Speaker 2:You have to remember that Kuperia is a parasite of young cattle, so if you put R2s with R1s, the R2s are a great source of refugia for Ostetagia and Trichostrongulus, but they're almost totally ineffective as refugia for Kuperia because their immune systems keep them out.
Speaker 1:Yeah, okay. So, yeah, fair enough. So that makes some sense or makes a lot of sense, yeah, excellent. So I guess what are the without making recommendations, because that's not a lot. Obviously you can't do that for individuals based on a podcast, but I guess what are the strategies that people need to talk to their vet about or make a plan around to if they are one of the unlucky ones? What are the strategies that we sort of the vets generally we talk to them about?
Speaker 2:We've dealt with a couple of farms that have done this. I mean, the obvious answer is you have to take the reliance away from drenches. So, and as Christian said before, these monocultures of young stock you know, intensively grazed, finishing systems with lots of young stock, they're almost 100% reliant on drench to control worms. And if they can't do that and they keep doing those systems, they're almost 100% relying on drench to control worms. And if they can't do that and they keep doing those systems, then they're going to end up with dead animals. I mean, it's almost as simple as that. So I'm just thinking of a couple of farmers who we've helped I think we helped and so they go to a more integrated system. So fewer young stock, more older stock, more cultivation, specialist forages and bring in some sheep. So, even if it's contract grazing for someone else, put some more sheep in the system, drop the level of larval challenge to those young animals and take some of the pressure off them, and so you don't need to drench as much.
Speaker 2:Yeah, um, but it's it's. It is as you said. It's quite tricky. And it's quite tricky for an individual farmer, because what suits one farm won't suit another. But what we tend to see is people just want to keep going. They just want well, give me something else to use. Well, I can sell you some Zolvix. Well, I can't. But you can go and buy some Zolvix, but it's going to make your eyes water when you pay the bill because it's four times the price of a triple and it's really hard to get. So you're not going to be wanting to use it very often.
Speaker 1:No, and I think, yeah, there's two problems with that strategy. Obviously you mentioned them both. But yeah, price, and then the fact that the more we hammer it, the less distance we'll get out of it as well. So, yeah, and it probably is a good thing that the price is staying up, and maybe that's part I mean, I don't know, maybe it's in their interest not to tell us, I suppose, but there's no new families coming down the line that there's not enough money in drenching cattle and sheep to justify massive investment in new chemicals. So we can't just sit back and go. Well, zolvik's turned up. I don't know what the next one's going to be, but there will be another one. But that seems to be pretty risky thinking.
Speaker 2:But that seems to be pretty risky thinking, I suspect the companies tell us that the market no longer justifies the investment. We all know that red tape's getting worse and worse, and it's the same for them. So the return on the investment has to keep going up and they can make so much more money out of cats, dogs and humans. Yeah.
Speaker 1:Yeah, and I'm right in thinking that most of our actives have actually come out of that, like they were just accidental results out of cats and dogs anyway. Aren't they most of our active chemicals, or have they been specific for?
Speaker 2:There would be some truth in that. You know, most of them initially would have been in humans and small animals and certainly in sheep. Sheep don't even appear on the pie chart when the drug companies show you the split for where all their money comes from. One of the drug companies, at a seminar I was at last year, said that if there is another drug for farm animals, it's likely to be a byproduct of something developed for one of the other markets. So it'll be something that's developed for cats and dogs and people and just by chance they said, oh well, we'll just register it for sheep. It won't be a sheep-specific product. No, no. So it's a mindset thing that farmers are going to have to get. You know, I see it. Virtually every farmer that I go to that's got a problem. You know, they've all got that mindset that they can't see past the drench gun. Yeah, because that's all they've known all their lives is the drench gun. And suddenly you say, well, you can't do that anymore. And they look at you and go what?
Speaker 1:Yeah, it's really, really annoying when stuff that you've relied on doesn't work anymore. That's right In the sheep industry. We've tackled it in the same way, but also with genetics. I've never heard of a worm egg outbreeding program in cattle. Is there one? Is anyone working on that? Does that make sense?
Speaker 2:We're hoping to. Beef and lamb genetics are currently doing an evaluation on the feasibility of starting something in the next year. Or so Cool, the feasibility of starting something in the next year? Or so Cool, there's probably a reasonable chance that that might come to play, yep.
Speaker 1:And would that be similar as in individual worm egg counts on calves, or is it going to be like more of a carla type, like a saliva type test?
Speaker 2:Don't know the answer to that at this point. Yeah, but the proposal I've seen involves both.
Speaker 1:Yeah, yeah, which would make sense, Just trying to think about how that's it's because it's a. I guess it's obviously a disease of the young animals, but if you can't get them to be old animals because they're dead, it's still fairly, it still can't be fairly important.
Speaker 2:Yeah, the relationship between egg count and worm burden in cattle is not as good as it is in sheep, right? So there's some discussion. It'll need some justification if FEC is going to work as a sampling procedure. Yeah, right.
Speaker 1:So that's sounding like a few years of research before that gets too close um, don't know.
Speaker 2:Yeah, I mean, the protocols are all established for sheep, so, um, but gathering the information and getting breeding values and stuff. There has been a little bit of work done in new zealand and there's currently some work being done. Uh, we're working with a group in france and another one, I think, in in Germany at the moment. Yeah, right, and they're quite interested. So it's not just a New Zealand problem, it's creating global interest.
Speaker 1:Yeah, excellent. What else is on the agenda in terms of your research group? What are the kind of big-ticket items that you're tackling?
Speaker 2:I'm going to leave that to the boss.
Speaker 3:It gets a little bit tricky. Research is not cheap. It's quite expensive and in the current environment, I think the whole research sector is struggling with funding. Whole research sector is struggling with funding. But we decided a while ago that we should move away from. When I was a phd student and when I joined the team we were focused on how can we delay the development of resistance in those parasites. I think we decided that we now have. We are at the stage where we only have one or two actives left and we need to move away from how do we delay the development of resistance to how do we manage parasites on farm without the reliance on drugs, without the reliance on drugs. So we have ideas about how to do that, but we need assurance, we need facts to base our decisions on and I think that is where the research in the near future has to go.
Speaker 1:Yeah, fair enough. All of research isn't nothing's getting cheaper and research is one of them. So it's a. It is a challenge to um to keep all that stuff going. This seems like fairly important stuff to me, they, and so hopefully you. You're successful in getting convincing someone of that, the um. I don't know what else we need to cover really. Is there anything else I haven't covered properly?
Speaker 2:For me, the only thing I mean, the message that farmers are going to have to get is and it's the same with sheep and it'll be with everything is for years we've gone into these farming, these monocultures. So lamb finishing, calf finishing these really intensive monocultures, you know so, lamb finishing, calf finishing these really intensive monocultures of a single stock class, and those days are probably just about done. You know, heifer, grazing for dairy industry, where a guy is entire farmers are one, you knowians, yeah, um, or jerseys, or whatever you know. And then, and that's a very interesting situation, because they bring in, they bring in calves from a whole lot of different properties and with them they bring their worms. Yeah, um, the owner. In many cases the owner dictates the drenching program, not the owner of the farm, the owner of the cattle, and it's in the contract that these animals will be drenched this many times with this product. Whether it works or not doesn't make any difference. And then all those cattle share all their worms together and they all go home. So it's a wonderful selective breeding program for resistant worms.
Speaker 2:So you know, you'd have to say, in fact, there was people at Massey 15, 20 years ago who said some of these systems are not sustainable and everyone just laughed at them. And it's becoming the case. So the hard sell for farmers is to change their entire farming operation. You know, if I was a farmer and I was running one of those monocultures of anything, now's the time to start having a conversation and saying well, look, I need to sit down with a consultant and a farm advisor and figure out how I'm going to diversify my operation to maintain my production and keep going for the next 10 or 20 years, because otherwise you might be in for a shock. Some of these people are getting some real shocks when they go out and there's a whole lot of dead animals lying all around the farm. They don't like that very much.
Speaker 1:No, it's not the highlight of many people's day. Yeah.
Speaker 3:I think it comes down to. Farming in the past was reliant on the use of drugs, and they were very attractive because they were relatively easy to use. You can just buy them, they were cheap, which means you can run a high productive system and can focus on production, and they absolutely worked. The problem is that's only true until they don't, and we are now at the point where they don't. The good thing is, I think they don't. The good thing is, I think it's not all doom and gloom. We know that it is possible to farm productively without that much reliance on on anthelmintics, and we know that there are farms out there which already do that. The hard bit is that we are now at the point where the farming industry has to change, and that's not easy.
Speaker 1:No, that's for sure, and I only learnt recently. Never actually thought about it before. But one of our previous guests mentioned that the barber's pole worm has almost the same size genome as humans do, so they're a perfect little pest really. They've got lots of DNA and massive selection pressure. We're always destined for trouble.
Speaker 3:Yeah.
Speaker 1:Excellent. Well, thanks gents. Awesome to have a chat. Yeah, look forward to seeing how that genetic works goes. That's going to be interesting and looking forward to promoting the hell out of that once we get a tool to work with Yep. Excellent, Thanks very much.
Speaker 2:All right.
Speaker 1:Thank you, cheers.
