Oregano essential oil and purple garlic have been used by humans since ancient times for their health properties, including helping to boost immunity and improving gut health.

However, now scientists have found these ingredients could be used in pig feed as an alternative to zinc oxide, which is administered to weaning piglets to prevent and reduce digestive problems.

Zinc oxide, which is a pollutant for the environment and contributes to the development of antimicrobial resistance, is in the process of being banned in many countries.

The study, by researchers in Scotland and Spain, found oregano essential oil and purple garlic offer similar or superior results to zinc oxide when added to feed in terms of the effects on the structure of the intestine, bacterial species present in the intestine and resistance to antimicrobials of indicator bacteria.

Several groups of weaned piglets received different concentrations of oregano essential oil and purple garlic powder, zinc oxide or a combination of both. A control group, which received none of these compounds in the feed, was also present for comparison.

The researchers found the piglet groups which received the highest doses of oregano essential oil and purple garlic powder had the best results for the measured parameters, and the results were similar or superior to those for the group that received zinc oxide.

The research was carried out in the Murcia region of Spain by scientists from Scotland's Rural College (SRUC), the University of Murcia and the Institute for Agricultural and Environmental Development (IMIDA), in collaboration with the pig producing company Dalland Hybrid Espana S.A..

It was conducted on a commercial farm to replicate the conditions found in a typical farm in order to facilitate the direct application of the results.

Jorge Rivera Gomis, Research Associate at SRUC's Centre for Epidemiology and Planetary Health in Inverness, said: "The weaning period is a critical step in pig production.

"This research on the use of oregano essential oil and purple garlic powder as alternatives to zinc oxide will help make pig production more resilient and sustainable by tackling current challenges such as antimicrobial resistance; reducing environmental contamination; meeting consumer demands of sustainably produced food; and adapting to new regulations and trends in animal production."