Additives as an alternative to zinc oxide in pig diets

 Find out how you can use additives to offset the removal of zinc oxide from pig diets. 

Back to Removing zinc oxide from pig diets

What are additives? 

In addition to inert fibres, a range of additives play an active role in supporting the gut health of pigs and offsetting the need for zinc oxide. As with all alternatives, additives must be considered alongside biosecurity, overall health, and good colostrum management.

Additives are usually active ingredients taken from nature, e.g. herbal compounds, probiotics (bacterial organisms added to feed in their inactive form), enzymes, organic acids and acid salts. There is also increasing interest in the use of viruses that target harmful bacteria, known as phages.

Read more about non-antibiotic feed additives in diets for pigs

What should I consider when adding active ingredients to feed? 

All additives add cost to the feed bill. These costs can be offset if the additive improves productivity.

To calculate the value of including additives in feed, you need to be measuring key performance indicators (KPIs), such as FCR, which include the feed used in a given period of time and either the average weight gain in that period or the daily liveweight gain (DLWG) and the number of days in that time period.

Find out more about pork key performance indicators

If the money saved in reducing the amount of feed needed to counter the post-weaning dip is more than the additive cost, it may be worth making the investment.  

This approach should only be taken after discussions with your vet and nutritionist and when biosecurity, health and colostrum management are of a high standard. 

Additive case study – testing what works on farm 

Zinc oxide has historically been included in pig diets to prevent post-weaning diarrhoea. However, high levels can have adverse effects on pig performance and the environment.  

Therefore, the EU has banned the use of medical zinc oxide from 2022. This, combined with the increased demand for a reduction in antibiotic use, drastically increases the need for the pig industry to find alternatives to help prevent intestinal disorders. 

The farm 

Kris Gios’ farm in Oosterhoven, Belgium, has been antibiotic-free since 2012. Until September 2017, a feed containing 2,000 ppm of zinc oxide was routinely used to prevent weaning diarrhoea and improve the intestinal health of his herd. 

The system 

Kris asked his feed company to come up with an alternative diet excluding zinc oxide. The suggestion was to include a combination of herbs, including oregano, at the following rates: 

  • Seven days before weaning to seven days post-weaning = 3mg herbs/kg feed 
  • Seven days post-weaning to day 28 post-weaning = 1.5mg herbs/kg feed 

Kris also trialled the inclusion of inert fibres in standard feed to ‘calm’ the intestine (reduce outbreaks of post-weaning diarrhoea).

Three groups of piglets were kept within the same barn. Each group was fed a different diet (either standard, herb-based or inert fibre) and weighed daily. Feed intake was monitored, and growth and feed conversion were calculated, along with the percentage saving (€/pig) across production.

The performance effects of the inclusion of herbs or inert fibres in place of zinc oxide need further investigation. However, this case study highlights the potential of additives to counter the removal of zinc oxide from pig diets.

At Kris’ farm, the feed containing herb extracts has been used for three months, with a positive effect, and the farm remains antibiotic-free. High doses of zinc oxide have been eliminated without sacrificing the health status of the farm.

NB. There was no estimate of the cost or efficacy of inert fibres provided in this case study.


The price of including herbs was 2.3% higher than the standard diet. 


  • Improved average daily gain, feed conversion rate and weaner survivability was observed when feeding herbs 
  • The mortality rate of weaners fed inert fibres declined, in line with the herb-based diet 
  • The overall effect of these improvements reduced production costs by 2.4%