Despite its best efforts, the US turkey industry continues to battle costly protozoal diseases such as coccidiosis, histomoniasis (blackhead disease) and Cochlosoma. While there are vaccines, medications and alternative products available for managing coccidiosis, there are few dependable options for managing the others. We also know little about how these protozoal diseases interact. Producers are left to deal with reduced performance or, in some cases, increased flock mortality rates. Not surprisingly, many are also evaluating alternative treatments.
To help the turkey industry get a firmer grip on protozoal diseases, Poultry Health Today organized a roundtable featuring three experts from research, production and industry. Each panelist shared experiences and provided ideas on how to address protozoal diseases and maintain the health, well-being and productivity of turkeys today.
The informative discussion was sponsored by the US poultry business of Zoetis. Following are the edited highlights from this insightful, one-hour roundtable.
CHONGXIAO (SEAN) CHEN, DVM, PhD
University of Georgia
MIKE LILBURN, PhD
Retired from The Ohio State University
KABEL ROBBINS, DVM, MSpVM, DACPV
DAVID RIVES, DVM
EDITOR’S NOTE: This booklet is based on the transcript of a recent roundtable. Statements were edited for brevity and clarity with the participants’ permission. The panelists were also given the opportunity to amend their original statements for context and accuracy.
Coccidiosis status and control
In 2021, Steven Clark conducted a National Turkey Federation survey of industry professionals and veterinarians that care for more than 80% of the turkeys produced in the US. They ranked coccidiosis as the top protozoal disease and No. 6 overall.
From your experience, how important is coccidiosis in the turkey industry today? And how successful are you at controlling it?
The reason that coccidiosis ranks the highest of all of the protozoa in the annual health surveys is that it’s so widespread. Almost every turkey flock will be exposed to coccidiosis to some degree at some point.
That makes it significant for all veterinarians, because we all have to deal with it on a regular basis. The thing that makes coccidiosis less severe is that we do have treatment options, unlike the other protozoal diseases that we face, for which there aren’t any options. But even the coccidiosis options are somewhat limited, especially if you compare turkeys to chickens.
So, that’s what puts it higher on the survey list. Also, having just one vaccine available for turkeys, with only two coccidial species in it, limits our coverage. When we look at our ionophore options, we have two (lasalocid and monensin). The chemical options, depending on what’s available at any given time, are limited for turkeys as well (amprolum diclazuril, zoalene and clopidol). And, of course, you may have a limited amount of time to use those chemicals without resistance developing.
As a turkey veterinarian, I find rotational programs very challenging for coccidiosis because of the limited number of products. As we try to incorporate them, we’re basically rotating back to products quicker than we should in an ideal program. That can lead to an increased rate of resistance in our populations — a situation that makes the disease an ongoing challenge for the industry. So, even though we do have a few options, we don’t have nearly enough for a strong coccidial program.
Also, with all of our control mechanisms applied through the feed, any type of enteric problem that reduces feed consumption or leads to birds going off feed means they are no longer receiving the anticoccidial control. Therefore, coccidiosis can quickly become a secondary pathogen in flocks with other enteric issues. That just further compounds problems and leads to more gut damage, causing production losses in those flocks as we get them later in life and onto the processing plant.
The thing that makes coccidiosis less severe is that we do have treatment options, unlike the other protozoal diseases that we face, for which there aren’t any options.KABEL ROBBINS, DVM, MSpVM, DACPV
Do you have a feel for the success rate of autogenous coccidiosis vaccines developed with some of the Eimeria species that may be involved in a targeted operation?
People have certainly tried to come up with autogenous vaccines. The challenge is that you’re basically taking a wild-type, fully virulent strain and giving it to a bird, maybe at an earlier age, to allow it to develop immunity in a more controlled fashion.
The problem is that we don’t have the ability to get attenuated or less-virulent organisms. There are some ideas being considered of how to get strains that can still develop immunity but not cause the level of disease. Some people are at least somewhat satisfied with the vaccine programs they’ve been working on, but I don’t think anyone believes that they’re the absolute solution. Autogenous vaccines also are complicated to develop and maintain, making it difficult to ensure that you’re getting the level of control you need.
We have a lot of opportunities on the vaccine front, both with commercial development involving more strains and potentially a better understanding of how to develop autogenous vaccine options that are more successful for the industry.
I want to follow up on autogenous vaccines and what I think are some real opportunities moving forward. I’ve had a good friend and colleague — Dr. Lisa Bielke at The Ohio State University — who’s become very involved in turkey coccidiosis. She recently published a paper on using polymerase chain reaction (PCR) technology to identify the predominant Eimeria strains across the Midwest.
I think PCR offers an opportunity to move forward within a company to identify the primary Eimeria strains in an operation and then, with someone like Lisa’s help, develop their own autogenous vaccine.
I think PCR offers an opportunity to move forward within a company to identify the primary Eimeria strains in an operation….MIKE LILBURN, PhD
Coccidiosis: Nutritional considerations
Have you been able to develop any strong opinions, one way or the other, about any of the phytonutrients in terms of gut health and damage related to coccidiosis?
Yes, there are some classes of phytonutrients that help augment a coccidiosis program specifically. And I’m saying cocci, specifically, because I don’t have any answers to blackhead disease (Histomonas meleagradis). One of the potential benefits of phytonutrient/botanical products is how the products are positioned in a cocci program. If a company is using a vaccine during a particular cycle, some of the phytonutrients may help take the edge off the vaccine challenge the birds are getting at young ages.
That’s where I see them augmenting some of the other additives we might use at the time. I couldn’t recommend a single phytonutrient or some of the newer botanical products on the market as stand-alone products. We have too much enteric “noise” in live production for these products to be used alone.
For example, I think some of the tannin products augment a vaccination program, especially if you’re using the only commercial vaccine, because there are only two Eimeria species in that particular vaccine. Some of these products may give you enough enteric support to offset the lack of Eimeria species differentiation.
I couldn’t recommend a single phytonutrient or some of the newer botanical products on the market as stand-alone products.MIKE LILBURN, PhD
Let’s discuss antibiotic-free production (ABF) and no-antibiotics-ever (NAE) production. According to Dr. Clark’s survey, 25% of US turkeys were produced in NAE or ABF systems in 2021. That really limits product options to use in coccidiosis control. What kind of effect is that having on gut health overall, cocci control, as well as some of the other protozoa?
Certainly, with NAE programs, ionophores are not allowed. So, we don’t have enough chemicals, plain and simple, to have a chemical-only rotational program that would be successful in turkeys. Therefore, you’re going to have to incorporate other aspects into that program, and vaccination is the only other option.
Once you eliminate ionophores from your program, it’s an added challenge to develop a program that’s successful for you, and figuring out what your specific cocci are and how to control them.
That could include using other products through the feed that can augment your cocci-control program within an NAE program to make it work a little better. But it also has to come down to more stringent attention to management, such as controlling litter moisture, the environment and all of those things, to control cocci cycling in NAE flocks.
The risk is certainly high with an NAE flock of having other gut damage occurring, whether it’s a primary viral disease or another protozoal or bacterial type of pathogen causing a problem. As you start to get excess nutrients into the hind gut, you can quickly get dysbacteriosis and other issues occurring that can make it hard to get back on track with an NAE program.
The risk is certainly high with an NAE flock of having other gut damage occurring, whether it’s a primary viral disease or another protozoal or bacterial type of pathogen causing a problem.KABEL ROBBINS, DVM, MSpVM, DACPV
One thing that the NAE program does, often in conjunction with welfare audits, is that it mandates more square footage per bird. And I think that’s a big plus for managing coccidiosis.
The other consideration is just what can individual turkey companies afford to do in terms of increasing downtime between cycles? That’s the missing link in many of these programs. The time of the year is another factor affecting cocci pressure. Most companies I’m familiar with don’t have the option to have 20 days of downtime in the brood phase and then 21 days or more when the birds are coming out the other end. This doesn’t really allow us to manage the litter optimally once the birds are gone.
We can no longer afford to use a lot of the management practices from 15 to 20 years ago. Also, a large proportion of the poults in the industry come directly from the two primary breeders, and I’ve been on farms that have had poults from as many as five or six different breeder flocks located in different states. I understand that those companies have to manage their production efficiencies as well. Between NAE and also having fewer medications available, “poult starts” during the first 2 weeks have become even more important, and we often need to go back to management 101.
There’s a wonderful paper written by Peter Poss at the University of Minnesota in 1998. A lot of things that Peter discussed back then, even when we had more medications, were related to improving management. Many of those suggestions are still applicable today, if we can afford to do them.
Just to remind people that when I first came to The Ohio State University in 1987, we were raising 30-pound toms in 18 weeks. So, when you look at today’s cocci and other enteric challenges, litter management (because the birds are consuming so much more feed), the conformation changes we’ve benefited from in terms of breast yield, and implementing welfare audits, the list of production challenges has increased significantly.
Management skills are just as critical today, if not more so.
Sean, have you done any research into nutrition’s role to address coccidiosis in NAE production?
Without the use of antibiotics, the things that we can manipulate in a turkey flock are very limited — mostly management and nutrition.
For nutrition, we can think about how we can improve it to reduce performance losses and save feed costs while the birds have a coccidiosis infection. Whenever birds have a cocci infection, their gut lining has been damaged, so their ability to use nutrients is limited.
If we keep the same feeding program, some of the nutrients may go to waste or may be utilized by the cocci instead of the bird. Perhaps there’s some nutrition program we can develop for the early infection stage to try to limit certain nutrients and starve the parasites. At the same time, we can look at supplying some functional nutrients, such as a functional amino acid, to improve the gut health and reduce performance loss during the early infection stage.
Those could be some strategies we may adopt in the near future.
Without the use of antibiotics, the things that we can manipulate in a turkey flock are very limited — mostly management and nutrition.CHONGXIAO (SEAN) CHEN, DVM, PhD
Coccidiosis: What is research revealing?
Sean, over the last few years, you’ve been on the forefront of research, especially with flagellated protozoa. I know you have some ideas concerning coccidiosis as well; please share those with us.
I’m not an expert in coccidiosis, but we did do some research related to coccidiosis in turkeys. One of the things we focused on is vaccination, and as noted, we have only one commercial product and it contains only two species of Eimeria.
Because of that, vaccines may have brought some inconsistent responses in the field, which is something we’re trying to focus on.
One response to the vaccine — actually, I would say it’s more like a side effect — is that it comes with costs. Sometimes you may see a performance loss while using the vaccine, especially for the first 3 to 5 weeks.
We observed a very interesting phenomenon during research trials. During the brooding period, if we increased the poults’ density, we saw a bodyweight reduction by week 5. However, when the density is lower, we don’t really see a performance reduction during that period. The cycling of coccidia might play an important role in the consequence of vaccination or infection.
To reduce this performance reduction, we’re thinking about another strategy — like Mike cited — using some feed additives to reduce or offset the vaccine’s side effects. We did some trials on that as well, to see if we can reduce the side effects due to early age for birds in the field.
We’ve seen some interesting effects, one of which is that sodium bisulfate, fed to the birds, is pretty good at reducing bodyweight loss while using vaccination. However, this is still a preliminary trial. We haven’t seen how this feed additive impacts bird health long term or the mechanism of how it works with vaccination.
But using feed additives combined with vaccinations to maintain the birds’ performance is something we can try in the field.
Sometimes you may see a performance loss while using the vaccine, especially for the first 3 to 5 weeks. The cycling of coccidia might play an important role in the consequence of vaccination or infection.CHONGXIAO (SEAN) CHEN, DVM, PhD
What do you think is the best way to evaluate the effectiveness of a cocci-control product? Is it bird performance? Litter conditions? Gut scrapings? Or is it a combination of all of these things? And do anticoccidial sensitivity tests ever come into consideration?
First, I want to answer your question from the research side. From my personal experience, when we look at the evaluation for a cocci infection, we’re looking at the shedding, performance and lesion score at a set time.
Looking at any of them individually may create some barriers. For example, if we only look at shedding in the litter or if you take a sample directly from the gut, we may see different numbers. And a lower number doesn’t necessarily mean the situation is better, because when the guts are severely damaged, it’s not optimal for the cocci to replicate. You may see some lower numbers, but it doesn’t mean the situation is better. So, combine the counting plus scoring together to better understand the situation.
Performance definitely is straightforward to see the condition of the birds. It’s also a good measure for commercial production, to see the better performance when we use any treatment to conquer the cocci.
Coccidiosis: What lies ahead?
If we want a long-term, sustainable approach, vaccines need to be our main focus while making strategic, judicious use of the few medications we have available.KABEL ROBBINS, DVM, MSpVM, DACPV
Looking ahead on coccidiosis, where do we go in the next 3 years? Do you anticipate doing anything different or just trying to balance things the way you have been?
Vaccination is the future for most disease problems that we face in the turkey industry, with coccidiosis certainly being one. If we want a long-term, sustainable approach, vaccines need to be our main focus while making strategic, judicious use of the few medications we have available.
Would I love to have additional chemical options? Yes, that would be great. But, realistically that’s not likely to happen. So, sitting back and hoping for the development or the approval and release of those products is not in the best interest of our industry.
We also need to understand our challenges even more by using the PCR methodologies and understanding what the specific species are that we’re faced with. Focus on the overall gut-health program; do those gut scrapings to know how our cocci program is working. Combine that with all of the other metrics that we use to evaluate performance, then we can make a determination of what our problem is and how to address it.
The turkey industry is really handicapped by the fact that you can’t just look at lesions in the bird, like you can with a chicken, and say this is the cocci species that I have. Even doing that under the microscope is very, very challenging on the turkey side.
So, using newer technologies, allowing PCR to identify your problem strain, and if it’s not included in your vaccine, then you need to figure out how to mitigate the issue. This can be the key to move us forward when cocci problems do arise, which they will.
I agree with Kabel’s assessment. Regarding chemicals, we have to add so much downtime between cycles when we use them today, that in some situations they’re almost not an option at all. Because if we used a particular product for one cycle and if the downtime is 2 years between cycles, we’ve effectively lost it.
It further emphasizes that we need to work on using PCR to identify which Eimeria species are endemic to our particular production environment.
The other thing I want to point out is, on the broiler side, we have all become so dependent on Greg Mathis of Southern Poultry Research over the years. For turkey coccidiosis research, there is John Barta at the University of Guelph in Canada, who’s kind of a master; and I previously mentioned Lisa Bielke, a young scientist at Ohio State who has carved out a niche in turkey coccidiosis through the validation and sharing of primers. If we can make them more available to more folks, it would be a huge step forward for us.
Regarding chemicals, we have to add so much downtime between cycles when we use them today, that in some situations they’re almost not an option at all.MIKE LILBURN, PhD
I want to follow up with that. Using primers to detect different strains of coccidia is a great idea. Dr. Li Zhang, assistant professor at Mississippi State University, is developing on-site scraping for bacteria in the flock. It can all be done in a trailer or truck on-site and get a result. The basis is isothermal amplification technology, and it’s pretty quick and easy to do on a farm. I believe that technology can adapt into on-site cocci detection for turkeys as well. That could be very interesting.
For the future, of course, the turkey industry is very small compared to broilers or laying hens. I don’t think we’re going to find a company that has millions of dollars to spend developing new drugs for cocci, especially with NAE production moving forward. We’ll probably have to rely on vaccination or even genetic selection for those lower-resistant strains in turkeys to solve this problem.
Enteric health: Nutritional factors
Mike, as a nutritionist you’ve formulated a lot of diets for turkeys to address both enteric health problems and also for optimizing performance. What are some things you’ve learned over the years in terms of maintaining gut health in the face of challenges like these protozoal diseases?
As mentioned, a lot of our medications are no longer available. Another thing that’s made it more challenging is the increase in NAE programs. That’s removed ionophores as one of our anti-coccidial options, and most folks have adopted some form of vaccination as part of their cycle of approaches.
My big concern with NAE is if there’s a low level of cocci that isn’t being managed in a house because of litter-moisture management issues, for example. If downtime becomes especially important to the success of a cocci-control program, we often do not have the option to increase downtime.
Another concern is secondary enteric challenges. When you get into NAE programs, we’re often forced to use excess protein — for example, 50% soybean meal in the first couple of diets. Even with a minor cocci challenge, there will be a lot of undigested protein getting to the lower gut, causing significant secondary bacterial issues.
Also, with NAE production, we don’t have the option of using meat and bone meal in the feed. We can use vegetable oils, which are good oils, but they are becoming problematic because biofuel is taking an increasing percentage of soybean oil.
Outside of medications, cost is the other thing about formulating diets to try to control enteric diseases. There’s not a single inexpensive medication out there, and we often use them in combination with other medications. So, it’s not just what a single medication costs, but what are we using in addition to, say, a cocci chemical? What else are we using in the diet? The medication combinations often are what’s driving up costs. Live-production managers in companies I worked with are constantly juggling nutritional aids from an ever-decreasing list of products that we have complete confidence in.
It’s also a seasonal issue; we have seasonal effects in all the companies. You routinely have enteritis popping up a couple of times a year, often in mid-winter, depending upon where you are located, and in the spring.
So, it’s a matter of what I am willing to invest in my diet at a time of the year when I know I’m going to have some enteritis issues.
My big concern with NAE is if there’s a low level of cocci that isn’t being managed in a house because of litter-moisture management issues.MIKE LILBURN, PhD
What else did you learn from your experience in the field?
The last thing I want to mention is that communication is really important — with the guy in the field, the nutritionist and results of the posting sessions. I’m still amazed at how many companies, even with in-house veterinarians, don’t have regularly scheduled posting sessions. It does a couple of things: It keeps you on top of what’s changing over time and shows you what changes were made.
The other thing it does from my perspective as an outside nutritionist, who wasn’t necessarily doing the formulations, is that all the service guys knew me. I would spend a couple of days in the field and at a posting session. I knew the service guys, so I kind of got the skinny behind what’s really happening in the field.
And that’s a really important form of communication. I could feed that information back to the people doing the formulations per se. In the last 10 years that was kind of my role working with some of the consulting companies; I would do their fieldwork and report back to them on what I was seeing.
That’s where we are in nutrition. There’s no silver bullet, but I do think that field observations and communications are really critical.
There’s no silver bullet, but I do think that field observations and communications are really critical.MIKE LILBURN, PhD
Histomoniasis (blackhead): Prevention options
Let’s move to the flagellated protozoa. According to the US Animal Health Association survey, histomoniasis rose in importance from 2021 to 2022. Part of the reason may be because when a break occurs, it causes significant mortality, and there are no efficacious preventive or control measures. I’d like to hear your thoughts on histomoniasis and what a producer can do to try to prevent it.
Yes, blackhead is a very frustrating disease. Thankfully, as we look at the entire industry, it’s a relatively low-incidence disease based on the number of flocks that are affected on an annual basis.
But for the individual flocks that are affected, this disease can be extremely devastating, especially for the individual farmer. The other reality is that blackhead often repeats on the same farms; it’s not a random chance of any flock in the country getting blackhead. There are risk factors associated with certain farms — where they’re located, their likelihood of getting the disease in a single flock but then repeatedly on successive flocks as well.
Companies in certain regions have a lot more challenges with it than others. Since there are no effective preventives or treatments, the only thing we really know to do is have effective biosecurity to try to keep it out. Understand what our main risk factors are, especially the nearby presence of long-lived chickens. Maintain good communication with our neighbors. Understand when those flocks may be departing farms or having litter cleanout procedures that may present more risk for having blackhead organisms transmitted onto our farm.
We also need to be aware of what’s happening on our farm. Do routine mortality necropsies to catch any issues early with a blackhead flock to try interventions with culling, maybe partitioning houses and other things along those lines to try to get ahead of an outbreak. Try to stop it from getting bird-to-bird transmission and maybe losing or having to destroy that entire flock of birds.
There are no good solutions for blackhead. It would be great if someone could develop a treatment solution, but we’ve been asking for that for quite some time and it hasn’t happened yet. Hopefully, it’s on the horizon, but realistically, we’re left to continue managing the disease.
Maintain good communication with our neighbors. Understand when those flocks may be departing farms or having litter cleanout procedures that may present more risk for having blackhead organisms transmitted onto our farm.KABEL ROBBINS, DVM, MSpVM, DACPV
I had hoped that as it became more of a problem for the broiler breeder segment of the poultry industry, our chances of getting something would improve. But it really hasn’t made much difference. Mike, what are your thoughts on histomoniasis?
Identifying it early in a house, getting some migration fences in there, and trying to sort out the affected birds is one approach.
Getting back to what I said earlier about cocci, you’re going to have problem houses. Doing a good job of cleanout in finish houses, windrowing where it’s applicable, also allowing downtime — those are really the only approaches on problem farms. Note that I didn’t say solutions; I said approaches.
It’s also important to understand the proximity of the flock and regional differences. In the Shenandoah Valley, for example, you will find every single commercial poultry species that exists somewhere in Rockingham County, Virginia. If you’re a company with multiple complexes, knowing which locations are susceptible environmentally and/or through proximity to other species is helpful. That at least gives you a starting point to try to establish a management program.
We really haven’t had any new methods or ways to control this disease. When we talk about blackhead control, we talk about two things: One is prevention of vectors bringing Histomonas meleagradis into a turkey barn; the other is outbreak management. These are two separate tasks with different philosophies.
For prevention, it’s actually very challenging, because technically we know that Heterakis gallinarum, the cecal worm, can bring Histomonas to a turkey barn. That’s something we are focusing on.
Meanwhile, many things can bring cecal worm eggs into a turkey barn, which makes it very challenging. Not only on the front line, like equipment, people — their boots, personal protection equipment — but also some vectors, such as earthworms, grasshoppers, darkling beetles. For some farms, we’ve seen these vectors be more of a challenge than we think. We see some interactions from the other parasites around a turkey barn, which makes control even more challenging. Also, some turkey barns are curtain-side, so we cannot seal the house completely, which means some of the vectors can fly into a barn. But a cable-side partition is a very effective measure.
While we need to control parasites, we also need pest control. Most of those products are not long-lasting, which is what we need in order to keep them away all the time. Even though most outbreaks we’re seeing are around 6 to 8 weeks, turkeys are susceptible to blackhead at any age.
But we also see some opportunities. First thing we can focus on is where to use pest control, because using it throughout the whole production system is not optimal, because it’s a lot of money and labor.
If we can predict when an outbreak may happen, then we can use pest control quarterly, and it will be more economical. There are some ways we could possibly do this; one is the season. During the warmer season, outbreaks occur more often compared to colder months, like wintertime.
Risks also increase when there’s a chicken farm near the turkey farm; we’ve seen this repeatedly be an issue in the field. When there’s a chicken farm nearby, 2 to 3 weeks after they clean-out you may start seeing signs of an outbreak in the nearest turkey barn. That could be a sign to level up your biosecurity or pest control for the turkey barn to try to prevent a potential outbreak.
We’ve seen examples in the field where people applied a long-lasting, granular-form pesticide around barns during production to cut off the outbreak cycle, which had lasted for years.
When we talk about blackhead control, we talk about two things: One is prevention of vectors bringing Histomonas meleagradis into a turkey barn; the other is outbreak management.CHONGXIAO (SEAN) CHEN, DVM, PhD
Histomoniasis (blackhead): Management priorities
What about the role of managers and management on the farm? What have you seen in the field?
It really depends on the farm manager; some are not as good at recognizing sick birds. When they depopulate the sick birds in a barn, they may miss some. So, the second-peak mortality may happen even after you depopulate or partition. One of the challenges is how to train farm managers to recognize sick birds and have a more efficient depopulation practice during an outbreak.
We recently looked into bedding materials. Right now, some producers are using rice hulls with pine shavings. In Canada, they also have some other materials. For example, they’re trying cedar shavings, which was believed to be bad for the bird’s respiratory system. But actually, some of the cases have shown positive impacts for reducing blackhead-outbreak frequency. So that’s something we are looking in to now.
There are some anecdotal reports from farms in Canada that are supplying a byproduct from cedar oil production through the waterline, which can reduce the mortality. We cannot yet confirm if it’s an impact from the water treatment directly or if the outbreak just reached a point where there’s no more transmission happening and the mortality stopped. That’s something we’re looking into as well, to see if it’s a potential new product or new measure that producers could use to control severe outbreaks
The broiler breeders also are having similar problems with blackhead. So, they can push the research forward to see if we can do something for them that can be applied to turkeys as well for control methods, to understand outbreak risk factors and disease severity. But a lot of work needs to be done.
One of the challenges is how to train farm managers to recognize sick birds and have a more efficient depopulation practice during an outbreak.CHONGXIAO (SEAN) CHEN, DVM, PhD
One thing that we haven’t hit on is the importance of concrete floors and how that is a major barrier. It’s not a solution but a major barrier, particularly for repeat farms. I think this is where we get into the correlation of facts, which means it’s not a causative type of relationship, but when you see an increase in one thing, you happen to see a corresponding increase in another.
We talked earlier about the potential importance of PCR testing to identify coccidial species, but I know you’ve used PCR with histomoniasis to identify potential vectors and sources of blackhead. Sean, how do you see that progressing?
When we look into the vectors, we are looking to see if they carry any Heterakis eggs, instead of Histomonas. Because the DNA density is really low in a big bug, if you’re just looking for the Histomonas itself, it’s hard to capture.
For example, when looking at the earthworm, it is a large bug, so we cannot really digest the whole earthworm and isolate the DNA from what’s inside the worm to try and pick up the very tiny Histomonas sequence. It’s very challenging.
We have to section them into different pieces and do the testing. Using the primers for Histomonas to look for the vectors may not be as practical as using the Heterakis egg sequence to test vectors. So, we’re looking into a different way, using the Heterakis eggs rather than Histomonas itself.
One thing that we haven’t hit on is the importance of concrete floors and how that is a major barrier. It’s not a solution but a major barrier, particularly for repeat farms.MIKE LILBURN, PhD
Cochlosoma: Infection, seasonality and management
Let’s continue to look at flagellated protozoa. In my experience doing necropsies and gut scrapings, there are two that show up fairly regularly. One is Tetratrichomonas or Trichomonas; the other is Cochlosoma. Both can be present in large numbers.
I’ve come to the conclusion that Trichomonas may be an indicator that things are out of balance, but it doesn’t do a lot of damage itself, whereas Cochlosoma can be a major pathogen and really disrupt the gut.
I’d like to get your perspectives on the effect of seasonality and timing of infection. When do you see Cochlosoma in turkey flocks?
Those are definitely the most common flagellated protozoa that I encounter, and I do see them on a routine basis. For us, the seasonality component is that summer and fall are the periods when we have the highest infection rates with flagellated protozoa.
As for the severity of the impact of each one, Tetratrichomonas predominantly is isolated into the ceca of the birds, whereas Cochlosoma affects the small intestine, which to me is the big differentiator. So, the Cochlosoma is actually impacting the digestion and absorption of the primary nutrients that the bird is trying to get out of its diet.
Tetratrichomonas is really only impacting the hind gut, having minimal impact on the bird’s nutritional requirements overall. I do agree that any insult to the small intestines that’s sending more nutrients to the hind gut is going to feed your Tetratrichomonas and lead to even higher levels. So, I think the amount of those organisms that you’re seeing can be directly related to the gut-health status of those flocks.
To me, Cochlosoma is definitely the more challenging one for us to deal with. Like we’ve said about blackhead, there are no treatments for Cochlosoma. After looking at lots of different products to try to find potential interventions, all we’re left with is just managing through the infection.
For us, the seasonality component is that summer and fall are the periods when we have the highest infection rates with flagellated protozoa.KABEL ROBBINS, DVM, MSpVM, DACPV
What are the management strategies that you apply to address Cochlosoma?
Ensuring that we’re giving that bird the best environment possible. We have to heat up the house environment to make them more comfortable. Control the airflow over those birds to ensure that we’re not chilling them or making them feel uncomfortable.
Then we have to do everything we can to encourage the birds to eat and drink. Walking the barns more frequently; getting birds up off the side walls, out of any huddles or groups they may be forming; encouraging them to go to the feed, kicking the feed lines and attracting them any way possible.
Obviously, those are management steps that we focus on every day but that become even more important when we’re going through a Cochlosoma problem.
I like to illustrate to our farmers that there are a lot of things they can do to make a Cochlosoma infection worse. If we don’t do all of these things, we can ensure that the flock is going to perform very poorly, and we may see mortality and other issues from Cochlosoma.
There isn’t much we can do to make the birds better, but we can at least allow them to work through the infection over several days or weeks. Slowly the flock will rebound, although the birds will never regain their full genetic ability. But with hard work and focusing on those management factors, they can turn into a decent flock of turkeys most of the time.
Certainly, there’s a seasonality. Companies that I work with, where we have biweekly conference calls, have a checklist of things they’re seeing every 2 weeks. We start getting into an “enteritis phase,” when they see an increase in enteritis. When they do postings, they’ll start seeing increases in Trichomonas, maybe some Cochlosoma.
All the things that we can do to have dry litter, good-quality excreta — there are many factors involved. The ability to move air is important. If you have tunnel-ventilated facilities, which tend to be newer facilities, that helps.
Understand that if you have an older house, you usually also have an older grower, and you may have to designate some service people to spend more time with some of them, addressing such things as how often do you walk the birds? How observant are you?
One thing we haven’t discussed is the water-sanitation program — not necessarily with respect to Cochlosoma and Trichomonas, but your overall incidence of enteritis. Are you getting some secondary issues because you do or don’t have a good water-sanitation program? Again, that requires attention, monitoring the pH in your waterlines and such.
The ability to move air is important. If you have tunnel-ventilated facilities, which tend to be newer facilities, that helps.MIKE LILBURN, PhD
Cochlosoma: Future products and research
Sean, I know you’ve had the opportunity to look at Cochlosoma in several different ways and screen a number of products for potential beneficial effects. What’s your takeaway from all that work you’ve done over the last couple of years?
We actually screen more products on Histomonas than Cochlosoma. Cochlosoma has not really caught much attention from the allied industry yet. But we’re trying to advertise that it is a problem, and you may want to look into how your product impacts Cochlosoma.
But we do screen products; if I remember correctly, we have tested 14 products in six categories. We have summarized them and done an analysis to see which category has more potential to reduce Cochlosoma numbers in the gut. That’s one way we evaluate the infection status.
We didn’t see any one type of product that showed much impact on reducing the numbers. But mixtures — like a mixture of two or more of the the essential oil herbal products and/or prebiotic/probiotic — have a better impact from the preliminary data we have.
Cochlosoma has not really caught much attention from the allied industry yet. But we’re trying to advertise that it is a problem….CHONGXIAO (SEAN) CHEN, DVM, PhD
What are some of the areas that you are researching for Cochlosoma or that need more research?
Cochlosoma research, there isn’t much in the literature and it hasn’t been updated for a long time. A lot of information that we have is from the field, from producers dealing with this problem. We still don’t know what the vector for Cochlosoma is; we haven’t figured out that simple question yet. Also, the transmission of Cochlosoma is really high. We see from the experimental findings, if we keep infected birds and non-infected birds in the same cage, within days the non-infected birds get sick from Cochlosoma.
We did look into the situation to understand why a Cochlosoma outbreak acts differently in different farms. Some have really bad performance, even mortality. Some of them just have some uniformity issues, but the birds perform pretty well in a later stage.
We looked into different isolates of Cochlosoma from different farms, to see if there’s any difference between them. But the results were similar between the isolates. It seems that species is not a big factor in the different outcomes of Cochlosoma infection.
The group also did some research on the infection time of a Cochlosoma and the impact on the birds’ performance, which is very interesting. The earlier the infection occurred, the more severe consequences we see both in mortality and performance, as well as some of the bacteria population in the gut. So, the differences we see between farms might be because of the infection time — whether the birds get Cochlosoma when they’re young or when they’re older.
Have you seen any particular coinfection issues with Cochlosoma surface in the field?
An interesting observation is whenever a farm complains of a Cochlosoma issue, they seldom complain of Histomonas. The same way on the reverse. We don’t know between these two parasites if they have a competitive relationship or it’s just because of the situation on the farm.
We do look into Tetratrichomonas and Cochlosoma to see the interaction. The coinfection of the two is not consistent. We don’t see that it makes the situation worse or better; it’s just here and there, and kind of everywhere. It’s hard to conclude that there’s a relationship between them. But we do look to see if there’s any environmental stress or coinfection that makes Cochlosoma worse.
One thing we see is if we increase the diet’s energy — feeding diets with a higher energy — that could create a better situation for a Cochlosoma infection. But the diets we are testing are commercial diets. We don’t know exactly what kind of components are actually improving the energy. So, it’s kind of a mystery.
Following that, we do some digestibility testing to see how Cochlosoma impacts nutrient utilization. It’s a bit complex but, in general, Cochlosoma definitely impacts the energy and amino acid utilization. However, we didn’t see much, just on the mineral side. Still, this information can potentially be used to design better diets for birds with Cochlosoma.
Also, there are some novel ideas we’re trying by providing some supplements to the water, which is still the most efficient way to treat for Cochlosoma. But we are looking for something more like a nutrient rather than feed additives.
For example, we’re looking at water-soluble amino acids, such as arginine. In swine, some amino acids can improve gut health or the gut development. So, we are trying to track that in turkeys to see if providing additional amino acids in the water can improve the situation.
We’ve gotten some positive preliminary data, but we still need to confirm if it’s working. The group will have a bigger trial early next year to confirm the findings and have a better idea if this strategy can work on Cochlosoma.
We looked into different isolates of Cochlosoma from different farms, to see if there’s any difference between them.CHONGXIAO (SEAN) CHEN, DVM, PhD
I’d like to ask Sean a question: Is glutamine one of the amino acids you’re looking at from the standpoint of beneficial effects? There’s some good data on this in swine.
That’s something I’m really interested in but haven’t looked into that yet. We see the glutamine impact on the cocci is pretty good. There’s one paper talking about increasing the glutamine levels and actually improve the gut morphology parameters from a cocci infection. It’s also an important energy source for the intestine.
The part that’s really interesting is you don’t have to go through approval to use additional amino acid in the water, and it’s a much faster option. You don’t have to change your diet formulation that will take several days to reach the birds, which is already late. But maybe we can try in the trial and see how it works.
I’m a firm believer in the use of enzymes and probiotics. However, the label “probiotics” has become so generic that it can be hard to know what exactly you are using.MIKE LILBURN, PhD
It sounds like basic husbandry and management are even more important in dealing with flagellated protozoal diseases. Certainly, with today’s high-performing birds there’s very little margin for error; you can’t afford to let things get away from you.
In closing, does anyone have any final thoughts?
I haven’t said much about nutrition, but from an overall enteric-health standpoint, I’m a firm believer in the use of enzymes and probiotics. However, the label “probiotics” has become so generic that it can be hard to know what exactly you are using.
But those are two supplements that I do think help the gut do what it’s supposed to do. In terms of pre-digestion or digestive aids, they help stabilize the microbiota in the gut. I believe that even normal birds are under some low-level enteric stress just because of the environment and their genetics, because we increase feed intake when we select for bodyweight. So, those two supplements — enzymes and probiotics — should be staples in all programs.
I actually want to make a follow-up comment. For blackhead disease, we have been testing 132 different products in six categories since 2016 with Dr. Robert Beckstead and the current lab. We did a meta-analysis in the lab to see which category has more potential to reduce mortality or lesion scores in the turkey. We definitely have different numbers of a product in each category, but we did get some interesting information.
The category where there’s the potential to reduce mortality is the functional carbohydrates, which mainly contains prebiotics or some fermentation products. It reduced mortality and lesion scores as well.
Another is a plant-extract product that showed some reduction in the ceca score in general.
These two categories have the potential to reduce Histomonas disease progression according to this data set. But it’s only within the lab; it’s not like meta-analysis from research available online. Also, from the data, we have observed that these products are more effective at reducing mortality during a mild outbreak. During a high-mortality outbreak, most products did not show much effect on alleviating the situation.
…from the data, we have observed that these products are more effective at reducing mortality during a mild outbreak.CHONGXIAO (SEAN) CHEN, DVM, PhD