Potentiated zinc and monovalent copper oxide as dietary supplements for weanling piglets: effects on systemic and mucosal immunity, gut permeability and fecal microbiota composition

Luca Marchetti^1*Raffaella Rebucci^1*Paola Cremonesi²Filippo Biscarini²Bianca Castiglioni²Davide Lanzoni¹Alessandra Monteiro³Yron Joseph Yabut Manaig³Valentino Bontempo¹

• ¹Department of Veterinary Medicine and Animal Sciences (DIVAS), University of Milan, Lodi, Italy
• ²Institute of Agricultural Biology and Biotechnology (IBBA), National Research Council (CNR), Lodi, Italy
• ³Animine Precision Minerals, Annecy, France

The ban on pharmacological zinc oxide dosages intended for weanling piglets has enhanced attention to the biological interplay between copper and zinc during the weaning period. The present study hypothesized the possibility to modulate piglets gut health parameters through different zinc/copperZn/Cu ratios administered via specialty oxide sources. A total of 84 piglets were selected after weaning and divided into 4 experimental treatments and the trial lasted 28 d. During the initial phase (days 0–14), the positive control (PC) received 2500 ppm of zinc provided as conventional zinc oxide (ZnO). In parallel, three additional treatment groups were applied, in which copper (Cu) and zinc (Zn) were supplemented using potentiated zinc oxide (Pot-ZnO) and monovalent copper oxide (Cu2O), at both European and non-European recommended inclusion levels: 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). The second phase (15-28 d) was characterized by lower Zn/Cu ratios. Better fecal score was detected on day 4 in PC group when compared to EU (p<0.01). Serum immunoglobulin AIgA increased in Non-EU- vs PC (p<0.05) at 14 d, while serum diamine-oxidase was lower in PC and Non-EU+ vs Non-EU- (p<0.05). Jejunal secretory immunoglobulins A (sIgA) increased in PC vs Non-EU- (p<0.01) at 28 d. Zn was higher in PC fecal samples (p<0.01) whereas fecal Cu was conditioned by treatments (p<0.05) at 14 d. Analysis of fecal microbiota showed a decreased Observed, Shannon and Simpson metricsbiodiversity in Non-EU-when compared to EU (p<0.05). Beta diversity highlighted a significant separation among groups at 14 d (p<0.01). Differential abundances evaluated at genus level revealed notable differences in terms of genera composition at 14 d among groups (Pp<0.05). In conclusion, Pot-ZnO and Cu2O administered within European levels of inclusion may represent a valid strategy to enhance gut health of piglets during the first two weeks after weaning.