How to produce piglets without zinc oxide

14 March 2023

Post-weaning diarrhea (PWD) is caused by Escherichia coli and it causes local and systemic effects such as diarrhea or dehydration. Sjölund et al. (2014) estimated that low-grade PWD entails annual costs of approximately €40 per sow.

Zinc oxide (ZnO) has been one of the most practical preventive/control measures, but since June 2022, the European Medicines Agency has banned its use in the European Union (EU).

Why has the use of ZnO been banned in the EU?

Why has the use of ZnO been banned in the EU?

The EU banned ZnO use mainly due to the accumulation of zinc in the environment because it supposes heavy metal contamination of the soil. The Committee for Medicinal Products for Veterinary Use (CVMP) reviewed the safety and effectiveness of food-producing species orally administered medicinal products containing ZnO and concluded that the overall benefit-risk balance is negative.
The two main reasons were:
  1. The risk (non-quantifiable at present) of the selection of multiple antimicrobial resistance genes associated with the use of ZnO.
  2. The absence of measures identified as effective in managing environmental zinc accumulation.

The consequences of ZnO on the intestinal flora of weaned pigs

Katouli et al. (2001) concluded that supplementing 2500 ppm dietary ZnO (therapeutic dose) to weaned pigs impacts positively the intestinal flora's stability and maintains the high diversity of coliforms.
However, they warn that this supplementation should be restricted to two weeks following weaning in veterinary practice because it is sufficient to reduce diarrhea.

Picture 1-2

ZnO primarily enhances voluntary feed intake of nursery pigs.

Issues feeding piglets with ZnO

Issues feeding piglets with ZnO

ZnO has been used in piglet nutrition to prevent PWD. However, its adverse effects on animals' performance are highlighted in many reports: an increase in antimicrobial resistance, the change in the piglets' microbiota, or the accumulation of zinc ions in vital organs are some of them.
Starke et al. (2014) have shown that applying dietary ZnO at high concentrations affects the metabolic activity and composition of the intestinal microbiota through a reduction of certain Lactobacillus species.

Increases the proportion of multi-resistant E. coli

Bednorz et al. (2013) observed that the proportion of multi-resistant E. coli was significantly increased in the ZnO group compared to the control (18.6% vs. 0%).

What is happening with edema disease?

What is happening with edema disease?

Shiga Toxin-Producing E. coli (STEC) can cause edema disease (sudden death, possibly paralysis, and eyelid edema). F18 Stx2e positive E. coli negative impact is characterized by neurological signs, and economic losses can be substantial due to sudden deaths, causing between 50 and 90% mortality in nursery-age pigs.
Edema disease mainly occurs in recently weaned pigs, although cases may be observed through the grower barns.
The disease may be sporadic or may affect an entire herd. Some affected pigs become inappetent, develop swelling of the eyelids and forehead, emit a peculiar squeal, and show incoordination and respiratory distress. There is usually no diarrhea or fever.
There is also growing evidence, that disease can be subclinical, where negative impact on zootechnical performance is described on positive farms for STEC.

How to manage pig production without ZnO?

How to manage pig production without ZnO?

There is no magic solution to mitigate the impact of removing ZnO from piglet diets; this change must be approach holistically.
Here are some of the options for handling PWD and edema disease without the use of ZnO.


Probiotics are live microorganisms that improve or restore the gut microbiota when administered in adequate amounts.

The most common probiotics used in pig production belong to the genera BacillusBifidobacteriumClostridiumEnterococcus, and Lactobacillus.

However, Canibe et al. (2022) claimed that observed effects on PWD are often marginal and the vast variation in experimental conditions, detection methods, and markers measured to monitor probiotic effects on piglet health makes it difficult to compare results adequately and draw generalized conclusions on the use of probiotics as an adequate alternative.

Plants and plant extracts

Also named phytogenic compounds, they are among the often-investigated and debated alternatives to antibiotics and ZnO for preventing PWD in piglets.

This group included dried plant material and extracts (essential oils or tannins), alone or combined with other compounds such as organic acids.

However, it must be considered that various interactions between different compounds may affect their mode of action. Moreover, a side effect of essential oils, for example, is their intrinsic odor and flavor, potentially affecting feed palatability.

In the case of tannins, among the more promising antimicrobial plant compounds as alternatives to antibiotics and ZnO, only a few published in vivo studies have addressed PWD directly.


Adding organic acids: citric, fumaric, lactic, propionic, benzoic, and formic acids to weaned pigs' diets or drinking water has shown beneficial effects in the gastrointestinal tract.

Organic acids alone or in mixtures with lactic acid are widely added to weaner diets and are considered a tool to reduce the risk of PWD.

However, multiple combinations and forms of these compounds call for further investigation to assess their effectiveness.

Milk replacers and milk components

These products aim to achieve the digestive system's optimal development and health.

The studies presented by Canibe et al. (2022) have demonstrated the beneficial effects of providing milk replacer/milk products on parameters defining gut health and immunity. However, most studies did not investigate the impact of these effects on preventing PWD, which needs to be explored.

Picture 2-1

There are some options for handling PWD without the use of ZnO.

Protein level

A low dietary crude protein level has been shown to lower the frequency of diarrhea in pigs due to lower microbial protein fermentation in the colon and improved conditions in the small intestine after weaning. It has been demonstrated by Batson et al. (2021), Larsen et al. (2021), and Lynegaard et al. (2021).

Moreover, one of the first actions taken after the onset of the edema disease is to implement a certain feeding restriction at weaning, trying to minimize the effects of the special energy and protein diet provided at this stage (elevation of intestinal pH, which favors growth of E. coli).

Creep feed

Piglets consuming feed during the lactation phase will eat more after weaning. One of the purposes of feeding creep feed is to "train" the digestive tract to produce enzymes to cope with the post-weaning situation. 

However, Canibe et al. (2022) affirmed that studies had shown a high variation in creep feed consumption.


ETEC infections are non-invasive, and the active induction of mucosal immunity is significant for achieving protection against PWD. There are different options, such as live oral vaccines for piglets.

For edema disease, it must be taken into account that intramuscular antibiotics can even worsen the condition by causing the massive release of toxins by acting on the bacteria. Therefore, toxoid vaccines, specifically designed to act on the toxin, are an effective alternative to the use of antibiotics on farms.

One of them are Shiga toxin toxoid vaccines. A single application to piglets from the 4th day of life generates an immunization that persists and protect piglets during the entire sensitive period of life of the piglets and that reduces mortality and clinical signs of the edema disease caused during transition and fattening period. Positive effect of the vaccination was described also in case of subclinical ED.


Reviewing the basic management concepts at the herd level is one of the main points for reducing the levels of stress in the piglets, especially in the weaning and post-weaning phases.

The 20 points plan from Madec is a good starting point.

Hygiene, environmental conditions, and facilities are other vital aspects to consider for the piglets' well-being at this critical moment in their productive life.




The vast positive effect that ZnO use had is hard to replace, so it is necessary to cope with its ban from a multifactorial perspective.
Adding some products to the feed and focusing on management (and on vaccines in the case of edema disease), are the most critical points to take into account.


AHBD Pork. Removing zinc oxide from pig diets.

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Katouli, M., Melin, L., Jensen-Waern, M., Wallgren, P. & Möllby, R. (2001). The effect of zinc oxide supplementation on the stability of the intestinal flora with special reference to composition of coliforms in weaned pigs. Journal of Applied Microbiology 87(4).

Larsen, C., Lynegaard, J.C., Pedersen, A.Ø., Kjeldsen, N.J., Hansen, C.F., Nielsen, J.P. & Amdi, C. (2021). A reduced CP level without medicinal zinc oxide does not alter the intestinal morphology in weaned pigs 24 days post-weaning. Animal, 15(4).

Lynegaard, J.C., Kjeldsen, N.J., Bache, J.K., Weber, N.R., Hansen, C.F., Nielsen, J.P. & Amdi, C. (2021). Low protein diets without medicinal zinc oxide for weaned pigs reduced diarrhea treatments and average daily gain. Animal, 15(1).

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