A WA study into microencapsulated zinc oxide (ZnO) as a treatment for reducing post-weaning diarrhoea (PWD) in piglets will prove to be of significant benefit to pork producers and the environment.

Australia’s Pork Cooperative Research Centre (CRC) and Zamira Life Sciences (ZLS) co-funded the research into the product, Shield Zn, with findings detailing a significant reduction in the therapeutic dose of ZnO required to treat PWD.

In the final report prepared by Pork CRC-sponsored researcher and porcine nutritionist, Dr Jae Kim of the Department of Agriculture and Food Western Australia, Dr Kim states that widely accepted pharmacological doses of zinc oxide have previously been criticised due to high levels of zinc excreted into the environment.

“Recently, a microencapsulated zinc oxide product was released on the market and the lipid-coated ZnO claimed to dramatically decrease inclusion of ZnO from 2,500-3,000 ppm to 100 ppm to achieve the same effect on PWD.

“Therefore, microencapsulated zinc oxide was evaluated as a solution for the environmental issue as well as controlling PWD.

“The results showed that inclusion of 100 ppm microencapsulated ZnO suppressed the
expression of PWD in both enterotoxigenic E. coli challenged and non-challenged pigs, and kept the plasma and faecal zinc levels to the levels of that found in the pigs fed a control diet without additional ZnO supplementation.”

Mr Dale Harris, sales and marketing director for ZLS, says Shield Zn will make it easier for farmers to dose piglets and will help alleviate concerns of high levels of zinc excretion into the environment through the effluent system.

“Zinc is a heavy metal, so you really want to minimise it in the environment. At a 3000 ppm dose of zinc, the product doesn’t actually get absorbed, it just gets excreted through the gut.

“The issue is you’re getting a high level of zinc going through the faeces and the effluent and that gets spread onto pastures or the general environment and with these sorts of things it can bio-accumulate.”

Mr Harris says the ZnO is finely micronised and milled down to very small particles before being processed and coated.

“The particles are sprayed with fine mists of non-gm soybean oil. As they go through the manufacturing process, the lipid binds around the outer surface of these micronised particles. It’s a very small coating but that’s enough to offer it protection.

“The lipid allows the product to go through the stomach without it being bound. Zinc (2+) ions have a fairly strong affinity for other materials and they can get adsorbed on to other particles and therefore they lose that divalent mechanism.

“It’s that divalent mechanism, being zinc (2+), which attracts it to the sights of the wall of the intestine where E. coli also wants to bind and that’s what’s blocking the E. coli from causing a disease problem. It’s competitive exclusion mostly.”

Mr Harris says Australia and Asia may soon emulate EU mandates reducing the acceptable level of ZnO given in diets to 250 ppm.

“A lot of countries try to emulate EU quality standards. If that occurs in Australia, Shield Zn could be used in that situation.

“There’s not really any difference in efficacy between this product and the high concentrate 3000 ppm product. It’s going to do the same job and it’s going to be around the same price but it’s not going to have anywhere near the same environmental impact.”

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