Adding a bio-response modifier and zinc oxide to piglet weaner diets influences immunological responses to weaning

Abstract

The effect of zinc oxide (ZnO) and a Mycobacterium smegmatis-derived bio-response modifier (BRM) supplementation on blood neutrophil functions, high-mobility group box 1 (HMGB1) protein and pro-inflammatory cytokine responses was studied in early weanling piglets. In total, 45 piglets were placed in the following five groups: basal diet only (I), supplemented with ZnO (II), supplemented with BRM (III), supplemented with ZnO plus BRM (IV) in basal diet and basal diet without weaning from dam (V). The phagocytic activity, superoxide anion and myeloperoxidase production in blood neutrophils and the concentrations of HMGB1, TNF-α, IFN-γ and IL-1β in blood plasma were measured before and after weaning. The neutrophil functions were impaired and the concentrations of HMGB1, inflammatory cytokines, were elevated in piglets during the post-weaning period. The neutrophil functions were not improved until Day 7 of weaning (P > 0.05) and pronounced elevation (P < 0.05) in the concentration of pro-inflammatory cytokines and HMGB1 was observed until Days 14 and 21 respectively, in Groups II and III. The addition of BRM plus ZnO in basal diet improved superoxide anion and myeloperoxidase production on Day 2 (P < 0.05) and decreased the TNF-α and IFN-γ concentrations on Day 7 (P < 0.05), with no significant change in the level of IL-1β and HMGB1 in Group IV. Finally, it is concluded that addition of ZnO plus BRM in the diet induced the neutrophil functions and reduced the inflammatory cytokine response much earlier to stimulate innate immunity than did ZnO or BRM alone.