Estimation of digestible zinc and copper in pigs: a meta-analysis approach

The objective of this study was to quantify the impact of Zn and Cu supplementation and nutritional factors on the digestible content of these minerals using a meta-analysis approach. A database derived from 24 publications and describing 142 experimental treatments was compiled. A model showed that positive effects of chelated, (linear and quadratic, P < 0.01) and inorganic Zn supplementation (P < 0.05) (linear and quadratic, P < 0.01), Zn from ingredients (linear, P < 0.01) and a negative linear effect of dietary Cu concentration (P = 0.067; R-2= 94%) on digestible Zn content. In other model, addition of phytase showed linear improvement of digestible Zn (P < 0.01; R-2= 96%). For digestible Cu, a model showed that chelated and inorganic Cu supplementation (P < 0.01) linearly increased digestible Cu while dietary Zn level decreased it (P < 0.01; R-2 = 93%). Dietary phytase did not impact digestible content of Cu. The digestibility of Zn and Cu depends on dietary supplementation of these minerals in diets but also on the interaction between these minerals. Finally, phytase supplementation improves digestible Zn content but not Cu.