241 - Towards More Sustainable Use of Trace Elements in Pig and Poultry Feeding

Abstract: Copper and zinc are essential trace elements, which play an important role in a large number of biological functions, including immunity and protection from oxidative stress. When supplied at pharmacological level, they may improve gut health and animal performance, especially during stressful periods. However, because of their low retention, most of the Cu and Zn ingested is excreted, contributing to harmful environmental impacts, such as accumulation in soils and water ecosystems, and toxicity to soil microorganisms and plants. A high level of Zn in feed may also contribute to the development of antibiotic resistance. Finally, Cu and Zn are limited natural resources that should be preserved and better recycled. To find a compromise between the positive and negative effects of Cu and Zn, we need a holistic approach considering animal performance and health, risk of microbial resistance, and risk for the environment. In that perspective, reducing dietary Cu and Zn supplies whilst maintaining satisfactory animal performance appears the most effective approach. However, to safely reduce Cu and Zn supplies, their requirements should be better evaluated and the dietary factors and mechanisms that significantly affect their bioavailability better understood. Improved manure management is another way to better control the risk of soil contamination, by concentrating these elements in organic fertilizers that might be transferred to regions with soil deficiency. In the recent years, the EU regulation on Cu and Zn content of animal feed and organic fertilizers played a major role in reducing their utilization in pig and poultry. For instance in pigs, compared to before 2003, Zn and Cu excretion was reduced by 65% (from 80 to 30 g/pig) and 80% (from 38 to 8 g/pig), respectively, as well as their concentration in excreta (from 2500 to 1000 mg Zn /kg DM ppm and from 1000 to 250 mg Cu /kg DM).