Excreted Cu and Zn can accumulate in the upper soil layer and harm its fertility. Thus, managing dietary contents in pig diets should reduce such risk. However, a limited supply of these essential trace elements to pig requires a better knowledge. This study aimed to evaluate the effect of three levels and two sources of Cu and Zn on performance and mineral status of fattening pigs. Four dietary treatments were compared including a negative control (NC) corresponding to the basal growing and finishing diets, without Zn and Cu supplementation (5 and 29 mg/kg Cu and Zn respectively); an intermediate level (O1) supplemented with Cu and Zn oxides (Cu2O and ZnO; CoRouge® and Hizox®, Animine, France), which provided on average 7.4 mg/kg Cu and 47.5 mg/kg Zn; two diets were supplemented with oxides (O2) or sulphates (PC, positive control) at maximal EU regulation levels (25 and 120 mg/kg for total Cu and Zn, respectively). Ninety-six pigs (24.3±3.3 kg BW) were allocated to one of the four experimental treatments and raised in individual pens during 14 weeks (up to 110.3±8.9 kg). Animal performance were measured and samples of plasma (at d1, d41 and d90), bones and liver (at slaughter) were collected. Every third week, samples of faeces were obtained to determine the dynamic of Cu and Zn excretion. Over the whole experimental period feed intake, body weight and feed conversion ratio were not affected by the level nor the source of Cu and Zn. Plasma Cu was not affected neither by treatment nor period, whereas plasma Zn increased with period but did not differed between treatments. Hepatic Cu increased (P<0.05) with dietary content, and a tendency for increase of bone Zn with dietary content (P<0.10) was observed. Faecal Cu and Zn decreased significantly (P<0.01) with dietary content. Although it seems possible to reduce dietary Cu and Zn without affecting performance, these results require to be validated in commercial farms with more challenging health constraints.
