The 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 Zinc (Zn) and Copper (Cu) supplementation according to European and non-European levels on the health and performance of pigs 14 d after weaning. A total of 120 piglets [initial body weight = 7.14 ± 0.92 kg] were divided into 4 experimental treatments: positive control (PC, 2,500 ppm of Zn, ZnO) and 3 treatments in which Zn and Cu were added 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). Growth performance, serum Zn and Cu concentrations, fecal score, blood biomarkers of intestinal integrity, and fecal microbial composition were examined and analyzed using GLM and MIXED procedures of SAS. Fecal samples at 14 d were collected and the V3–V4 hypervariable regions of the bacterial 16S gene were sequenced in one Illumina MiSeq run. Body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), feed conversion ratio (FCR) and (feed efficiency (FE) were not affected by the experimental treatments. The fecal score suggests that during the first 14d, the consistency of the feces tended (P < 0.10) to be less in the three treatment groups while in PC, the greatest concentration of Zn favored a better fecal consistency. The initial serum Zn and Cu concentrations were similar for all dietary treatment groups. After 14 d, serum Zn concentration was significantly greater in PC (15.71 ± 6.25 µg/L, P < 0.05). No differences were highlighted in serum Zn concentration among the other 3 treatment groups. Serum Cu concentrations revealed statistically significant results (P < 0.05) on 14 d after weaning in EU, non-EU+ and non-EU- groups, showing greater concentrations of Cu (17.65 ± 5.49 µmol/L, 17.73± 3.46 µmol/L 18.33 ± 4.13 µmol/L, respectively) compared with PC (11.87 ± 3.60 µmol/L). These results suggested that the EU level of inclusion of both potentiated Zn and monovalent Cu is enough to reach the same Cu and Zn plasma concentrations of non-EU treatments. Plasma DAO was negatively (P < 0.05) affected in non-EU-. Firmicutes and Bacteroidetes were the most abundant phyla in fecal microbiome. 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 fecal samples, the presence of genera linked to a greater disruption of the gut barrier (Escherichia-Shigella) was depicted in non-EU- group, indicating significant modifications of the microbial community. These results suggest the need for 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 enhance weanling piglets gut health and to reduce the environmental impact.