Relationship between potentiated zinc oxide and monovalent copper in a dietary administration for weanling piglets

The aim of this study was to evaluate different dietary level of inclusion of Zn and Cu according to banned, European and non-European levels at 14d after weaning of piglets. The endpoints considered were growth performance, serum Zn status, faecal score, blood biomarkers of intestinal integrity and faecal microbial composition to elucidate if Zn and Cu novel formulations could induce modifications of the gut microbial community. A total of 120 piglets (7.143 ± 0.924 kg) were divided into 4 experimental treatments: positive control (PC, 2500 ppm of Zinc through ZnO) and 3 treatments in which Cu and Zn supplemented through potentiated ZnO and Cu2O according to different European and non-European levels of inclusion: EU (120 ppm of Zn; 140 ppm of Cu), non-EU+ (300 ppm of Zn; 200 ppm of Cu) and non-EU- (300 ppm of Zn; 140 ppm of Cu). Performance data were analysed using the MIXED procedure of SAS. Zn and Cu serum concentrations were evaluated through a GLM procedure of SAS. Serum concentrations of diamine oxidase (DAO) as indirect markers of intestinal permeability and Zn/Cu levels were analysed through a MIXED procedure of SAS at 0d and 14d. Fecal samples (14d) were collected and the V3–V4 hypervariable regions of the bacterial 16S gene were sequenced in one MiSeq (Illumina) run. BW, ADG, ADFI, FCR and FE were not affected by the experimental treatments. The faecal score suggests that during the first 14 days of trial the consistency of the faeces tended to be lower in the three treatment groups while in PC the high concentration of zinc favoured a better faecal consistency. The initial serum Zn and Cu concentrations at 0d was similar for the dietary treatment groups. Zinc serum concentration was significantly higher in the PC (15.71 ± 6.25 µg/L, p<0.05). No differences were highlighted in serum zinc concentration between the treatment groups. Copper concentrations revealed statistically significant results (P<0.05) on day 14 after weaning in T1, T2 and T3 groups that showed a higher concentration (17.65 ± 5.49 µmol/l, 17.73± 3.46 µmol/l 18.33 ± 4.13 µmol/l) of copper compared to CTR (11.87 ± 3.60 µmol/l). These results suggested that the European level of inclusion of both potentiated Zn and monovalent Cu is enough to reach the same Cu and Zn plasma levels of non-EU treatments. Plasma DAO was negatively (p<0.05) affected in non-EU- treatment. Firmicutes and Bacteroidetes were the most abundant phyla in fecal microbiota. Non-EU- contributed to a significant decrease in biodiversity in fecal microbiota as depicted with Shannon for diversity and Simpson for evenness indexes (p<0.05). In faecal samples collected on day 14the presence of genera linked to a higher disrupt of the gut barrier (Escherichia-Shigella) was depicted in non-EU- indicating significant modifications of the microbial community. These results suggest the need of a balanced supplementation of Cu and Zn through more bioavailable sources. The use of potentiated ZnO and Cu2O according to European levels could represent a valid strategy to replace pharmacological ZnO, enhancing gut health of weanling piglets and reducing the environmental impact.