Pig farming

The ban on Zinc and the reoccurrence of Oedema Disease

Historically the pig industry used antimicrobials in the diets of young pigs to control disease, such as post weaning diarrhoea (PWD), however the UK pig industry has now drastically reduced its reliance on antimicrobial use. We do currently have a very effective non-antibiotic method for prevention of PWD and that is inclusion of zinc oxide (ZnO) in the diet. Zinc is a heavy metal, and when a pig has absorbed sufficient amounts for its own body’s requirements the rest is excreted in the faeces. Unfortunately, this means the environment can then be contaminated with Zinc when slurry is spread. This is the main reason that the EU has announced a ban on ZnO inclusion into pig diets by 2022.

Zinc is such a common addition into the feed of young pigs it is likely that we will see a big increase in PWD after its removal. Another condition which is likely to increase is Oedema Disease. Oedema disease used to be seen quite commonly, but Zinc is normally very good at preventing it. Oedema Disease is caused by an infection with a particular strain of E. coli, that produces toxins which affect the vascular system of the pig, and produces a distinctive set of clinical signs:

  • Swelling around the eyes and forehead
  • A peculiar squeal/squeak
  • Incoordination
  • Breathing difficulties
  • Recumbency
  • There is usually no diarrhoea or fever

This disease is normally seen in the few weeks post weaning, and the signs may be confused with meningitis, but the swollen “puffy” eyes are normally a good indication that Oedema Disease is the cause. Your vet can confirm this by postmortem examination and culture of the E. coli from the pig’s gut.

The ban on inclusion of ZnO remains controversial. The scientific basis for the environmental contamination is not clear and, considering the addition of ZnO is chiefly in young pigs which produce a very small amount of slurry, the extent of it is not believed to be large. The other issue about the removal of ZnO is that, although there could be some small environmental benefits, it will probably be accompanied by an increase in antimicrobial use to control PWD and Oedema Disease which would be a big step backwards in the industry’s efforts to reduce its antimicrobial use.

For further information please contact please contact Zoetis UK Limited, First Floor, Birchwood Building, Springfield Drive, Leatherhead KT22 7LP. www.zoetis.co.uk. Customer Support: 0845 300 8034. Use medicines responsibly (www.noah.co.uk/responsible). Date of preparation: September 2020 MM-10501