In the perspective of reducing environmental impacts, this study aimed to assess impacts of reduced dietary copper (Cu) and zinc (Zn) supplementation on the growth performance and mineral status of fattening pigs. Ninety-six pigs weaned at 21 days of age were assigned one of four dietary treatments: a diet with no Cu or Zn supplementation (WS, 5 mg Cu and 29 mg Zn per kg feed); a diet supplemented with Cu and Zn oxides at an intermediate level (OINT, 7.4 mg Cu and 47.5 mg Zn per kg feed); and two diets supplemented with Cu and Zn oxides (OREG) or Cu and Zn sulphates (SREG) at levels reaching the maximum levels authorized in the European Union (25 mg Cu and 120 mg Zn per kg feed). The pigs were raised in individual pens until slaughter. Over the entire experimental period, growth performance was not influenced by the dietary Cu and Zn content, nor by the Cu and Zn source used for supplementation. Plasma Cu and Zn contents were not influenced by the treatments. Liver Cu content increased (P < 0.05) as dietary Cu content increased. Bone Cu and Zn contents and bone physical characteristics were not influenced by the dietary treatments. As expected, faecal Cu and Zn contents decreased (P < 0.01) as dietary Cu and Zn contents decreased. Thus, excretion of Cu and Zn in faeces could be decreased by decreasing dietary supplementation of these elements for fattening pigs, without influencing growth performance or mineral status. However, these results need to be validated on commercial farms with group housing and more diverse sanitary conditions.
