From June 2022, a zinc oxide ban, prohibiting the use of therapeutic doses of zinc oxide (ZnO) in animal feeds to control post-weaning diarrhea in piglets will come into effect in the European Union (EU). What does that mean for pig producers in Europe and beyond? Dr. Jules Taylor-Pickard, director of Alltech Gut Health Management, joins us on Ag Future to discuss what pig producers need to know about the ban, the impacts of ZnO on the environment and solutions that help replace ZnO in piglets' diets.
The following is an edited transcript of the Ag Future podcast episode with Dr. Jules Taylor-Pickard hosted by Tom Martin. Click below to hear the full audio or listen to the episode on Apple Podcasts or Spotify.
Tom: I’m Tom Martin, and in this edition of Ag Future, we’re discussing the use of zinc oxide, (which is) set to be banned by the European Union as a veterinary medicinal product in 2022. Joining us from Dunboyne, Ireland, is Jules Taylor-Pickard, director of Alltech Gut Health Management. Dr. Taylor-Pickard is a nutritionist, obtaining her Ph.D. specializing in piglet gut health, physiology and immunity. In her role at Alltech, she focuses on providing solutions to optimize animal performance and efficiency.
Dr. Pickard: Thank you, Tom.
Tom: Was zinc oxide seen as a solution after the use of antibiotics was banned in Europe over concerns about increasing levels of antimicrobial resistance?
Dr. Pickard: Absolutely, yes. So, producers discovered that antibiotics have the ability to promote growth as early as the 1940s. And then, in the decades that followed, producers actually relied quite heavily on antibiotic growth promoters — particularly pre-starter and starter feeds for piglets — to control those pathogenic infections. And so, it’s common practice. And so, various governmental bodies banned the use of antibiotic growth promotors (in) the European Union. That was in 2006.
So, that was brought into practice. And they banned the antibiotic growth promoters because of concerns around microbial resistance. And what was interesting, in the European Union — when they banned them in 2006, a lot of producers, they carried on using the antibiotics to what we would call the eleventh hour. So, they used it right off until they were banned, and the stocks have diminished. And all they simply did, really, was move to zinc oxide, then. It would work. It was readily available. So, they didn’t have to deal with as big of a problem as what they are going to have to now, when we look at zinc oxide, because they (won’t) have something that they could just easily switch over to.
Tom: Well, why has the use of high levels of zinc oxide in swine nutritional diets increased so dramatically in recent years?
Dr. Pickard: Quite simply, it works. It helps to decrease the incidents of scouring that we typically see in the post-weaning period, helps to maintain daily liveweight gain (and) reduce susceptibility to disease. It’s relatively inexpensive. It’s readily available. And of course, we’re seeing increasing regulation just around normal antibiotic use — so not just antibiotic growth promotor, which is obviously banned in the European Union.
And there’s many beneficial effects of zinc oxide — so, improvements in digestion, immunity. It has antibacterial actions, (is linked to) improvement in intestinal morphology and integrity and enhanced antioxidant capability — all those things that help to get that piglet through that critical post-weaning period.
Tom: And now, there is this EU ban, beginning next summer, on the use of high levels of zinc oxide in piglet diets. What’s the problem with zinc oxide in piglet growth and health?
Dr. Pickard: So, there’s a number of issues. (The) first one will be toxicity. We don’t actually see that too much, but you can get toxic effects of zinc in the pig if it’s fed for too long. Now, typically, they’d feed it for two weeks, which isn’t too bad.
And I should also say, when we’re talking about high levels of zinc oxide, we’re talking about around 2,000, 2,500, 3,000 ppm, whereas the requirement for zinc to the pig is 150 ppm. So, we’re not talking about meeting the nutritional requirements of the piglets for zinc, which will slightly be elevated levels. So, if you fed them for a prolonged period of time, you can get toxicity in the pigs, which we don’t see too much of.
But of course, there’s environmental issues, because you’re getting zinc secretion into the manure, which is then applied to the land. There’s also issues with zinc oxide accelerating antibiotic-resistant genes and the spread of antibiotic resistance. And there’s an increase in heavy metal-intolerant genes and the spread of that. And you also get modification of the microbiotic or the microbial population. So, there’s a number of concerns that are genuine around use of zinc oxide.
Tom: You just touched on this: There have been recent reports highlighting the environmental impact of zinc oxide. Can you expand on that for us?
Dr. Pickard: Yeah. Yeah. So, I like to say the main issue is related to the environment because the pig will just — for itself, it will just utilize the zinc that’s required for maintenance and growth, which I’ve said is about 150 ppm. So, anything that it doesn’t use is then excreted into manure. And obviously, we have to get rid of that manure. So, we apply it to the land. And due to the nonvolatile or non-degradable physical, chemical properties of zinc, the long-term continuous application of manure onto crops and land progressively increases the concentration of zinc into the soil, and then you also, obviously, get that into the groundwater.
There was an interesting study that was published that looks at zinc levels between the period of 1986 and 2014 from lands that have had the application of slurries and pig farms where they’ve been using zinc oxide. Now, they saw a great soil zinc concentration of 2–5%, which doesn't seem very much, but when you look at the latter period between 1998 and 2014, there was an average increase of over 24%. And obviously, there’s, there’s a risk, as I’ve said, of it getting into the water, affecting aquatic species as well.
Now, we do have risk mitigation measures in place, which are implemented, such as manure dilution, ensuring that any manure is spread from a safe distance from surface waters. But the European Medicines Agency concluded that these precautions just simply delay the inevitable, really, which is why we’re seeing the ban next year.
Tom: How has zinc oxide turned out to contribute to the spread of antimicrobial resistance?
Dr. Pickard: So, there’s quite a few studies and reports showing that zinc oxide does contribute to antimicrobial resistance, and that’s because the high levels of zinc oxide can increase the proportion of multi-resistant E. coli in the intestines of pigs, for example. So, a lot of studies have shown that you can get an increase in the persistence and prevalence of methicillin-resistant Staphylococcus, for example. That’s probably due to the co-localization of zinc and methicillin in resistant genes.
And you also get a diffusion of resistant genes amongst E. coli in the intestine of the pig. So, you’re enhancing it in the pig, which is a reservoir, if you will, to enhance that resistance even further. So then, you see more resistance in the feces, in the digesta, and in the colon. And you also have an issue with heavy metal-tolerant E. coli. I mean, a lot of those have been identified, which can further jeopardize the efficacy of zinc oxide. So, there’s quite a few concerns, now, with this whole resistance issue.
Tom: Can pharmaceutical-level doses of zinc oxide in the early post-weaning period suppress the growth of beneficial bacteria?
Dr. Pickard: Yeah. No, again, this is interesting, because the actual mode of action of zinc oxide is really poorly understood. We just know that it works, and it helps get that baby pig through that post-weaning period, but the impact on the intestinal microbiota isn’t that clear-cut. So, there is some data that suggests that in minor or transient modifications to the hindgut bacterial population, whereas other studies get a remarkable effect on those populations — and some do show a suppression of the growth of the beneficial bacteria, such as Lactobacilli, showing that you get a reduction.
But the modulatory activity of zinc oxide on the commensal microbiota, it’s thought, resembled the activity of growth-promoting antibiotics — so, suppressing the Gram-positive species without actually directly affecting the Gram-negative strains, bringing that effect to lower the bacterial activity, the ATP or the energy concentration in the guts of piglets, which makes more energy available to the host at the cost of losing some beneficial bacteria.
So, although you might be losing some beneficial bacteria, we do ultimately see the improvements in performance in the pig. So, even though you are getting that suppression, the beneficial bacteria is thought to be short-term and transient — another loss of performance.
Tom: Will the EU ban on zinc oxide apply to all animal feeds, or is it specific to feeds intended for piglets?
Dr. Pickard: It’s specific to feeds intended for piglets, because being able to use these high pharmacological levels of zinc oxide is (only done) under veterinary prescription, but what they found is that the veterinary prescriptions are used quite broadly. And that only applies to the pig sector. So, it is purely for the pigs.
Tom: Why is it essential to optimize gut structures in microbial populations in piglets?
Dr. Pickard: So, as you probably know, most weaning piglets are subject to a multitude of stresses over a short period, (and) that contributes to disturbances within the gastrointestinal tract and immune system — but some of those stresses, it could be nutritional. So, you’re changing the diet from cow’s milk to a dry, solid, pelleted diet that they’re not used to. You’re changing their environment, so they’re moving from being in the farrowing house with the sow to nursery accommodation.
(With) that mixing of litter mates, you’ve got health-based issues. So, you’ve lost that passive immunity from the sow that’s found in the milk. They tend to be immunocompromised because of stress and, then, maternal separation, mixing with other pigs. But what you do tend to get is you get a lower feed intake during that immediate post-weaning period. And when you get that low feed intake, you get significant changes in the structure of the villi in the gastrointestinal tract.
So, many of you have seen the structure of a good gut. The villi — the nice, tall, finger-like villi — they have quite a thin wall over which to absorb nutrients. The nutrient digestion and absorption is quite efficient. But when they don’t eat and they don’t have the nutrients, these nice, tall, finger-like villi change to fat, thick, thumb-like villi. So, the surface area through which to absorb nutrients is reduced. And because they’re thicker, the efficiency of that nutrient absorption and digestion is reduced. So, in effect, you have a multiplying effect. They’re not eating enough, but then that efficiency of nutrient digestion and absorption is reduced. So, that gives you your poor growth performance. And that’s when we also see this increased susceptibility or incidence to post-weaning diarrhea.
Anything that we can do to optimize gut health in those early days is really critical to the whole functionality of that young piglet and will have an impact on (its) subsequent health performance. A recent study actually said that producers experiencing an issue with post-weaning diarrhea, which is normally due to enterotoxigenic E. coli, costs about $680 per year. And in the present time, that’s money that our producers can’t afford to lose.
Tom: Do piglets have very specific needs to establish good gut health and functions and to limit disease?
Dr. Pickard: Early-life nutrition is critical. The only thing I would add is that 70% of the new system tissues are found in the gastrointestinal tract. So, I think that helps put it into context as to how important gut health is, because, obviously, if 70% of the new system cells are based in the gut, if it’s not going to work properly, then you are going to see increased disease and mortality, comorbidities, things like that.
Tom: In a swine market without zinc oxide, what are some nutritional approaches that could be used to potentially reduce the incidences of post-weaning diarrhea?
Dr. Pickard: So, there’s a number of things that you can look at. There’s obviously nutrition management and health. But if we just focus on nutrition, we can adjust the diet composition. So, for example, we’re looking at feeding lower crude protein levels. And the aim of that is to reduce the amount of undigested protein reaching the large intestine, so that reduces the incidence of post-weaning diarrhea and improves intestinal health.
We can increase the dietary fiber level post-weaning. That helps to reduce shedding. It also affects the retention time of digesta along the gastrointestinal tract. You can use things like organic acid, acid secretion in the gut of the piglet. It takes time to adapt to those dry-pellet diets; those can add acid. It helps to promote good gastrointestinal conditions and healthy digestion and helps to reduce post-weaning diarrhea.
Tom: Well, Dr. Taylor-Pickard, what is your recommended nutritional approach for these early nursery diets?
Dr. Pickard: I think it’s important to be able to understand that there isn’t a silver bullet to removing zinc oxide from diets. We’ve done a lot of work in this area. You have to take a holistic approach. I would always start with the sow. And if we can clean the sow up — and when I say that, I mean, for example, we’ve been feeding some of our technologies to the sows so that we can reduce the pathogen load in sows. So that, in turn, reduces the maternal transfer of pathogens to that baby pig both in utero and at birth. And that also influences the microbiome or the microflora of that baby pig at birth. So, as soon as it’s born, it’s got the favorable microorganisms that we want, and you’ve got a better gut microflora.
We also see things like increased colostrum quantity, increased colostrum quality — so, a higher level of immunoglobulin, so you’re getting back the passive transfer of immunity to that baby pig. So, we typically see less infections, less piglet mortality, high weaning rates. Look at the creep feeding. Make sure that — we’re trying to get at least 200 g of creep feeding to that baby pig while he’s still suckling the sow, because that also aids the transition to those solid diets, because he’s used to eating solid diets. And that, further, helps to get that higher-weight weaning. So, when the piglets are older or heavier at weaning, it makes that whole post-weaning transition process a lot easier.
Typically, a lot of our producers forget about water. So, we do spend time looking at water quality (and) water flow rate to make sure that they drink — because if piglets drink, they will then eat. So, that helps to get the pigs eating. A lot of the problem with the post-weaning growth check starts (with the fact) that the pigs don’t eat. So, if we can get them to eat, it does have a huge impact.
You need to look at things like vaccination program, biosecurity and hygiene, and look at any stress factors in the environment. So, obviously, it really is a holistic approach. You have to look at everything. And the earlier you can start it — so, I would say, if you start with the sow, the better chances you have of getting that piglet through that post-weaning growth-check period.
Tom: What about insoluble fibers such as oat and soybean hulls, wheat bran (or) wheat middlings?
Dr. Pickard: Yeah. There’s a lot of emphasis on fiber at the moment. So, we know that dietary fiber can improve gut health. It promotes bacterial community and increases hindgut fermentation. If we increase hindgut fermentation, we can prevent diarrhea or disease. So, if we look specifically at the insoluble fiber sources that you just mentioned, these are relatively resistant to fermentation in the hindgut. They accelerate the passage rate of the digesta. So, that prevents the proliferation and colonization of pathogens. So, yes, there’s a huge role for insoluble fiber sources in post-weaning diets to help us to reduce the incidence of post-weaning diarrhea.
Tom: How do you think this ban on zinc oxide will affect pig-producing countries outside of the EU? For example, do you anticipate future regulatory restrictions on the use of zinc oxide in the U.S.?
Dr. Pickard: Absolutely. If we look at some of the things that are already happening — with Canada, for example. Until recently, they’ve typically included zinc oxide at between 2,500 to 5,000 ppm, but Canada is now in the process of imposing similar restrictions to that of the EU. And they will lower their levels, we’re thinking, to around 350 ppm. China actually reduced their levels in 2018. They were using around 2,200 ppm, and they dropped it to 1,600. So, not quite at the levels that we’re at; they’re still quite high. But I know that they’re looking to Europe again, with a view to reduce them even more.
For the United States and for some Asian countries, it's definitely not a case of “if”; it’s a case of “when”. And it’s very clear that they’re watching Europe to see what happens. So, it will definitely come into play. As I say, it’s just a case of “when” — and not knowing.
Tom: Alltech has a Seed, Feed, Weed solution that can help remove zinc oxide from piglet diets. Tell us about that approach.
Dr. Pickard: So, as we talked about, a healthy gut is really important, with a good microbial population that allows us to maximize the health and lifetime performance of pigs and, obviously, to help our producers to profit still. Therefore, that’s why we look at nutritional strategies that can promote gut health. And that’s one of the things that’s our core competency on the monogastric side.
So, the Seed, Feed, Weed concept is one of our gut health programs, and it’s designed to modify the gut microbial population. So, we’re looking at establishing a more diverse and favorable microbial population as quickly as possible after this. So, we work with pig producers to implement the Seed, Feed, Weed program. And it’s basically got three components. The first one is “seeding” the guts with favorable organisms to give us good performance. We then “feed” those favorable organisms, which helps to further create a favorable environment, which provides a competitive advantage to those favorable organisms that’s tolerant to acidic environments, unlike pathogens. So, yes, we’ve taken the balance toward the good guys, the favorable bacteria. And then, finally, using Actigen, we “weed” out the unfavorable bacteria by selective exclusion.
So, (we) incorporate natural feed materials — for example, Actigen — that are proven to maintain a healthy gut for the normalizing of gut microflora in both sows and piglets. And as I mentioned earlier, (the) maternal gut health of the sow is intrinsically linked to that of the offspring, which, again, is why our goal is start with the sow. So, it’s all about getting the piglets off to the best possible start, but Seed, Feed, Weed is just that: It’s seeding the gut with favorable organisms, it’s feeding those favorable organisms, and it’s weeding out the unfavorable or the bad organisms.
Tom: All right. We've been talking with Jules Taylor-Pickard, director of Alltech Gut Health Management. We thank you for joining us.
Dr. Pickard: Thank you, Tom. And thank you for having me.
Tom: And for Ag Future, I'm Tom Martin. Thanks for listening.
This has been Ag Future, presented by Alltech. Thank you for joining us. Be sure to subscribe to Ag Future wherever you listen to podcasts.