Management of post-weaning diarrhoea and the implications for AMR in response to the upcoming ban on zinc supplementation in pigs.

Piglet weaning is a critical life-stage, associated with high vulnerability to diarrhoeal disease and poor weight gain. Post-weaning diarrhoea (PWD) is a condition that causes considerable economic loss to the pig industry due to the impact on this most pivotal phase of a pig's production cycle. Zinc oxide (ZnO) is currently used as a feed additive at pharmacological levels of 2500 ppm to mitigate the challenges during weaning, reducing diarrhoeal incidence while improving production measures such as weight gain. However, there is an environmental impact of high ZnO usage, which is also associated with an increase in antimicrobial resistance within the pig gut microbiota. From mid-2022, ZnO supplementation of weaner/post-weaning piglet diets will not be permitted above a maximum level of 150 ppm. It is anticipated that this will result in an increase in PWD, impacting pig productivity, animal health and welfare. This project will have two main objectives, the first the establishment of a bio-bank of pre- and post-ban faecal samples for microbial analysis to elucidate the impact of the ZnO ban on pathogen occurrence, antimicrobial resistance indicator genes and microflora composition in weaning and later aged pigs. The second, an epidemiological analysis of data from participating farms to identify potential risk factors affecting diarrhoeal disease, together with on-farm motivations and barriers towards management of health throughout the weaning period. The immediate months prior to implementation of the June 2022 ban, together with the period of withdrawal, present a unique opportunity to objectively compare the pre- and post-ban experience of PWD within the UK pig sector. Directly working with stakeholders, this project aims to identify practical measures for on-farm implementation to reduce disease occurrence and improve productivity, whilst providing information to help offset the uncertainty accompanying the transition to "zero zinc".