Gastro-intestinal tract (GIT) disorders, infections and diarrhoea increase at
the time of weaning in young pigs. This causes large economic losses in the pig
industry. Preventive use of antibiotic growth promoters and metal trace
elements (Cu, Zn) in weaning diets has contributed largely to alleviate these
problems for approximately half a century. However, increased concerned on
bacterial resistance to antibiotics in humans and animals, as well as developing
environmental pollution caused by high copper levels in animal slurry have
progressively led to a partial and then a total ban on the preventive use of such
antibiotics in feed. Despite this, medicated weaning feed are still common
practice due to the lack of completely satisfactory alternative solutions for
keeping post-weaning (PW) disorders under control. Antibiotic growth
promoters have been shown to act through many different mechanisms