SUPPLEMENT ARTICLE Effect of weaning and in-feed high doses of zinc oxide on zinc levels in different body compartments of piglets R. Davin 1 , E.G. Manzanilla 1 , K.C. Klasing 2 and J.F. P erez 1 1 Grup de Nutrici  o, Maneig i Benestar Animal, Departament de Ci encia Animal i dels Aliments, Universitat Aut onoma de Barcelona, Bellaterra, Barcelona, Spain, and 2 Department of Animal Science, University of California, Davis, CA, USA Summary High doses of Zn are widely used for prevention and treatment of diarrhoea in weaning piglets; however, the mechanism of action of Zn against diarrhoea is still not well understood. The objective of this study was to evalu- ate whether weaning induces Zn deficiency in piglets. Eight litters of primiparous sows were selected for the experiment, and 3 piglets presenting similar weights were selected within each litter. Two of the three selected piglets from each litter were weaned at 21d of age and fed two different diets: a commercial control diet (WCt) and the same diet plus 2000 ppm of Zn as ZnO (WZn). The third selected pig from each litter was kept unweaned (Uw) with the sow and the rest of the litter. All 24 selected animals were killed at 28 d of age, and blood, gastro- intestinal content, liver, pancreas and spleen were sampled for Zn, Fe and Cu analysis (mg/kg or L of sample). Data were analysed using ANOVA including treatment as a fixed factor. Weaned pigs fed WCt diet presented a lower Zn concentration in plasma than Uw animals (0.76  0.091 vs. 1.10  0.099 mg/L, p = 0.05). Zinc levels in liver, pancreas and spleen were not affected by weaning. Total concentration of Zn was higher in gastrointesti- nal contents of weaned animals fed WCt diet than in Uw pigs (p  0.001 for stomach, jejunum, ileum, caecum and colon). Supplementation with high doses of ZnO increased levels of Zn in gastrointestinal content (p < 0.001), liver (p < 0.001) and pancreas (p < 0.001) compared to WCt diet. It also increased plasma Zn to non-deficient levels (1.32  0.086), but the increase was not as marked as in other locations and final concentra- tion was not different than that in Uw animals (p = 0.231). Weaning creates a Zn deficiency situation in weaned pigs as observed by plasma Zn concentrations. ZnO supplementation counteracts Zn deficiency. Keywords deficiency, intestinal content, pig, plasma, weaning, zinc Correspondence R. Davin, Grup de Nutrici o, Maneig i Benestar Animal, Departament de Ci encia Animal i dels Aliments, Edifici V, Universitat Aut onoma de Barcelona, 08193 Cerdanyola del Vall es, Barcelona, Spain. Tel: +34 935811556; Fax: +34 935811494; E-mail: roger.davin@gmail.com Received: 15 March 2012; accepted: 26 July 2012 Introduction Use of in-feed pharmacological levels of zinc (Zn, 2000–2500 ppm) as zinc oxide (ZnO) is widely accepted in pig industry for prevention and treatment of diarrhoea in early weaned pigs, especially in some EU countries after the antibiotic growth promoter ban in 2006 (European Commission, 2010). However, this practice has raised concerns about its environmental impact and it has to be eventually reduced (EFSA, 2010). The use of Zn for diarrhoea control is mainly empirical, and understanding its mode of action would provide important information to find alterna- tives or reduce the high doses currently used. For many years, high in-feed doses of ZnO were perceived as an antimicrobial treatment that could decrease en- terotoxigenic E. coli colonization and bacterial popula- tion in the gastrointestinal tract (Fairbrother et al., 2005). However, some studies indicate that 2500– 3000 mg/kg of dietary ZnO does not always modify or even may increase E. coli population in the GIT (Højberg et al., 2005; Molist et al., 2011). Alterna- tively, other hypotheses have proposed that Zn may improve the intestinal barrier function (Li et al., 2001), avoid bacterial adhesion to the epithelium (Roselli et al., 2003) and modulate the expression of genes encoding various stress response proteins (heat, inflammation, infection, oxidative stress) in entero- cytes (Sargeant et al., 2011). These new hypothesis raise the role of Zn as a nutrient involved in many Journal of Animal Physiology and Animal Nutrition 97 (2013) 6–12 © 2013 Blackwell Verlag GmbH 6 DOI: 10.1111/jpn.12046