The Alltech Feeding Times Issue 36 - Winter 2021 Winter 2021 - Page 18


The following is an edited transcript of the Ag Future podcast episode , hosted by Tom Martin , featuring Amanda Radke . Listen to the episode on Apple Podcasts or Spotify .
Amanda Radke is a fifth-generation cattle rancher from Mitchell , South Dakota , and a blogger for BEEF Magazine who has dedicated her career to serving as a voice for the nation ’ s beef producers . She travels the country speaking to agricultural groups about hot industry topics .

Amanda joins us to talk about a recent experience as a panelist at an Alltechsponsored conference leading up to the U . N . Food System Summit , where she brought a producer ’ s perspective to an important discussion about the efficient use of resources . Welcome to Ag Future , Amanda .

Well , thanks for having me .
The panel that you participated in looked at the future of protein security and how to maximize the efficiency of production resources without unintended social , cultural and environmental consequences . You were the only producer on that panel . And first of all , I ’ m wondering if you went into the discussion anticipating having to defend production practices .
Yeah . I kind of chuckled because I felt , “ Oh , I ’ m missing the ‘ Ph . D .’ behind my name . I ’ m not sure if I ’ m qualified to speak on this .” And , you know , the Alltech folks assured me , “ No , no , we want someone that ’ s actually , you know , managing the land and taking care of the cattle and can offer that perspective .”
And so , I was really proud to be able to represent beef producers from here and around the world and highlight some of the things that we already do very well in regards to managing our land and responsibly taking
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 promoter, 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. 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? 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. You just touched on this: There have been recent reports highlighting the environmental impact of zinc oxide. Can you expand on that for us? 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 18 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 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. How has zinc oxide turned out to contribute to the spread of antimicrobial resistance? 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. Can pharmaceutical-level doses of zinc oxide in the early post-weaning period suppress the growth of beneficial bacteria? 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. THE FEEDING TIMES