The immediate postweaning period in pigs is often characterised by a reduced and variable food intake and poor growth and development, reducing lifetime performance. At present the effects of the postweaning growth check are reduced by the use of antibiotic growth promoters (AGPs), copper sulphate and zinc oxide to enhance the efficiency of feed conversion and hence maximise nutrient capture. However from January 2006 the routine use of in feed AGPs is to be banned and, due to concern over environmental pollution, levels of inclusion of heavy metals are likely to be further reduced. Weaning pigs from the sow at an older age, when their digestive systems are more mature, has been suggested as an approach to reduce the potential negative effect of the AGP ban on the national herd. The objective of the AGEWEAN programme of research is to investigate the effects of weaning age (4, 6 and 8 weeks) in both an indoor and outdoor lactation environment on biological and economic efficiency of a production system where diets contain no AGPs and lower levels of copper (<25ppm added) and zinc (<100ppm added).