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Zinc: Diarrhoea treatment in piglets and… children

The use of high levels of zinc oxide in piglet diets for prevention of post-weaning diarrhoea is a hot topic because of the recent opinion by the CVMP. But apart from this legal discussion, zinc oxide is also a very unique compound we use, not noticing it, in products like skin ointments, dandruff shampoo or anti-odour powders for shoes to name some.

Can we learn something useful from other uses of zinc? In 2010, I was involved with a project to find alternatives to zinc oxide in piglets and I certainly learned something very interesting.

How does zinc oxide work?

Any pig farmer will tell you how well zinc oxide works to control post-weaning diarrhoea. However, nobody knows exactly how it works. There is plenty of information on its effects on microbiota and the intestinal epithelium; but not much beyond that.

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In our project we wanted to understand how zinc oxide actually works to develop better alternatives. And the first question we had was: who proposed the use of zinc oxide for prevention of post-weaning diarrhoea? And why? We did not answer this question.

However, the PhD student working in the project, Roger Davin, found some very interesting information.

Diarrhoea treatment in children

Zinc, along with oral rehydration solutions (ORS), is considered by the World Health Organization (WHO) the only treatment recommended to reduce the duration and severity of diarrhoea in children. Not antibiotics, not probiotics, but zinc.

It was quite surprising for us to find such information. The same treatment as for piglets! Not only zinc, but oral rehydration solutions were also recommended. Sound familiar? Maybe if I told you that oral rehydration solutions are similar to what we call electrolytes for piglets, then it makes sense.

The secret of those solutions is very simple and at the same time an amazing concept: salt and sugar will not help against diarrhoea if given separated, but they will save your life if combined. They need to be together to favour water absorption. Now you know, make sure the electrolytes you use for piglets have glucose and sodium together.

Are piglets deficient in zinc?

But let’s go back to zinc. In children, populations with diarrhoea are deficient in zinc and have a low level of zinc in blood. After zinc supplementation the improvement is fast as blood levels of zinc go back to normal levels.

A pig’s blood stream needs to have a good supply of zinc in order for the animal not to become immunosuppressed. Photo: Dreamstime
A pig’s blood stream needs to have a good supply of zinc in order for the animal not to become immunosuppressed. Photo: Dreamstime

We decided to investigate this in piglets and the results were clear. The level of zinc in the blood of piglets before weaning was similar to the levels in the blood of healthy children. The level of zinc in the blood of piglets after weaning was similar to the levels in the blood of children with diarrhoea.

Drop in zinc levels with piglets

And this drop in zinc levels happened as fast as 2 days post weaning. Roger Davin tested more than 15 products, including zinc oxide, zinc sulfate, nano-zinc and other organic and inorganic sources of zinc at nutritional doses for piglets. However, only zinc oxide added at doses higher than 1,000 ppm was able to return blood zinc to normal levels. Those are the same levels discussed by David Burch.

Zinc is the trace element involved in more biological functions than any other micro-mineral in the nutrition of the early weaned pig. At the same time it disappears from the organism of the piglet much faster than similar elements like iron or copper. Thus, a piglet that does not have a proper supply of zinc will be immunosuppressed and will have many physiological functions will be affected within days.

New innovative ways to replace zinc oxide?

Should we start looking for new innovative ways to replace high levels of zinc oxide? Is zinc oxide really acting as a medicine in that context? Should we go back to look at it from a nutritional point of view? And most important, will the CVMP cause a severe nutrient deficiency in piglets by not allowing the use of high levels of zinc oxide in diets?

16 comments

  • David Burch

    Fascinating work Edgar. At least CVMP can be in no doubt about the efficacy of the product. Hence, my disappointment in their decision, which could damage the health and welfare of 250 million piglets a year in the EU. The resistance issues have been over-emphasised in comparison with antibiotic use and the major concern of environmental issues could be monitored and controlled if there was a will. It calls into question the sustainability of many pig farmers and it is hoped the European Commission will reverse or revise the decision. Regards David

  • That is right David. I think they took the decision too fast with no real discussion.
    Regards!

  • Stefano Calamanti

    Probably, zinc oxide increases linkages between enterocytes by not allowing bacterial toxins and allergens to penetrate into the intestinal mucosa.
    Other molecules such as betaine may have the same function

    ACTA VETERINARIA ET ZOOTECHNICA SINICA 2009, Vol. 40 Issue (11): 0-1644 DOI:
    动物营养 Current Issue| Next Issue| Archive| Adv Search |
    Effect of High Level of Zinc Oxide on Tight Junction Protein Expression in Intestinal Epithelial Cells and Intestinal Mucosal Barrier in Early Weaning Piglets
    HU Caihong*, QIAN Zhongcang, LIU Haiping,XU Yong
    Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Science, Zhejiang University, Hangzhou 310029, China
    Mitochondrial adaptations to NaCl. Complex I is protected by anti-oxidants and small heat shock proteins, whereas complex II is protected by proline and betaine.
    Hamilton EW 3rd1, Heckathorn SA.

  • That is one of the function Stefano. I think we need to find the key functions beyond the gut. And we will. Cheers

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  • Bill VANDAELE

    I agree with the statement at the end "Is Zinc Oxide really acting as a medicine in that context.? Should we go back to look at it from a nutritional point of view?". In fact, yes, the EU authorities authorise Zn to be added as feed additive up to 120 ppm in feed and as such Zn deficiencies are avoided both in animals and in humans eating porc meat!
    Only problem is that at higher doses it is a vet médicine and as such needs to be registered and therefore satisfy all requirements, quality, efficay and safety for target species, consumers , users and also environment!! Today no data are provided to satisfy the legal requirements for environmental safety and therefore CVMP cannor tecommend to keep those VM on the market. Once this risk assessment is made, yes, then the risk managers can find practical solutions to keep the médicine, Under some conditions on the market in some countries; but certainly not in areas with intensive pig farming. Dr Bill VANDAELE consultant in reg affairs for feed additives /vet med and author of a thesis on Environmental Risk Assessment of ZnO as potential vet médicine.

  • That is right Bill, there is a conflict between legislation and actual use. However ZnO was once moved from being and additive to medicine. Nothing avoids the opposite. Copper, recently modified as additive could had been moved to medicine too. Also, the criteria for deficiency assessment is too focused on productive performance unfortunately.

    Cheers

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