Vetagro Journal Club, #4

June 2022: one of the most dreaded deadlines for the European swine sector. After this date, zinc oxide at a pharmacological dosage will no longer be allowed: quite a problem for weaning piglets! 

We can certainly manage the farm environment as well as possible, apply the best biosecurity measures and implement the most expensive feeding programs, but we all know that this might not be enough to prevent and mitigate the post-weaning syndrome. Phasing out pharmacological levels of zinc oxide will come at a cost that will surely impact lifelong performance of pigs. The search for solutions to replace zinc oxide has already begun but navigating among all of the many claims that the feed additive industry is making can sometimes be confusing…. 

But don’t worry, we’ve got you covered! We recently published a review on Animals, in collaboration with the University of Bologna, “Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglet”.

It is true that the extensive use of zinc oxide in swine is not without negative effects as if it is used for too long or in too high doses can have some toxicity; there is an environmental problem of soil and water pollution, plus some clues are suggesting an increase in antibiotic resistance in pathogenic bacteria. The ban stems from these considerations, but, and this is a big but: the pros outweighed the cons until recently. Now that we are forced to go in another direction we need to reconsider our journey and take the path that is best for us, by choosing the right feed additives for our weaning diets. This review wants to be a self-help guide to ZnO alternatives starting from understanding the basis of the use and success of ZnO as a preventive measure of post-weaning diarrhea at the same time reviewing the strength and limitations of the main in-feed alternatives to medicinal levels of ZnO.

A curious note about ZnO is that still little is known about the precise mechanism of action: many positive outcomes are described with its use such as improved nutrient digestibility, probably due to a better intestinal morphology, a decrease in the local inflammatory response, an increase in the antioxidant status and an aspecific and moderate antibacterial effect. The only thing that is certain though, is that all of these effects are not related to elemental Zn but rather to the oxide form. The proof is that any other salt, even the more available chloride and sulfate, does not bear the same outcome. Why is that? Well, it seems that the oxide form confers some sort of physical protection to the intestinal epithelia and improves intestinal health in a way more soluble forms of Zn aren’t able to do. This suggests that any replacement of ZnO should take into account intestinal health at 360 degrees.

But what could we do if we wanted to replace zinc oxide? For sure there are some alternatives, although a combination of more solutions is more likely to succeed: low protein/low buffering capacity diets combined with organic acids for example, and or the very fashionable essential oils and natural identical compounds, which are known for their antimicrobial and anti-inflammatory properties. Other reported promising tools are polyphenols and natural extracts, as well as prebiotics, probiotics, the more the merrier!

Caution though… any implemented solution needs to be thoroughly assessed. The more we know about all of these work the better chance we will have to implement them successfully. That being said, June 2022 is no longer as frightening as before! Science and practitioner are working, researching, and finding out as many solutions as possible to maintain and improve animal health and production, with an eye to environmental and medical problems.

A review of Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglets, by Bonetti et al. (2021) Animals. 11, 642: Click here

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