title: Dose-dependent effects of dietary zinc oxide on bacterial communities and metabolic profiles in the ileum of weaned pigs.
abstract: Pharmacological levels of zinc oxide (ZnO) can improve the health of weaning piglets and influence the intestinal microbiota. This experiment aimed at studying the dose-response effect of five dietary concentrations of ZnO on small intestinal bacteria and metabolite profiles. Fifteen piglets, weaned at 25 ± 1 days of age, were allocated into five groups according to body weight and litter. Diets were formulated to contain 50 (basal diet), 150, 250, 1000 and 2500 mg zinc/kg by adding analytical-grade (>98% purity) ZnO to the basal diet and fed ad libitum for 14 days after a 7-day adaptation period on the basal diet. Ileal bacterial community profiles were analysed by denaturing gradient gel electrophoresis and selected bacterial groups quantified by real-time PCR. Concentrations of ileal volatile fatty acids (VFA), D- and L-lactate and ammonia were determined. Species richness, Shannon diversity and evenness were significantly higher at high ZnO levels. Quantitative PCR revealed lowest total bacterial counts in the 50 mg/kg group. Increasing ZnO levels led to an increase (p = 0.017) in enterobacteria from log 4.0 cfu/g digesta (50 mg/kg) to log 6.7 cfu/g digesta (2500 mg/kg). Lactic acid bacteria were not influenced (p = 0.687) and clostridial cluster XIVa declined (p = 0.035) at highest ZnO level. Concentration of total, D- and L-lactate and propionate was not affected (p = 0.736, p = 0.290 and p = 0.630), but concentrations of ileal total VFA, acetate and butyrate increased markedly from 50 to 150 mg/kg and decreased with further increasing zinc levels and reached low levels again at 2500 mg/kg (p = 0.048, p = 0.048 and p = 0.097). Ammonia decreased (p < 0.006) with increasing dietary ZnO level. In conclusion, increasing levels of dietary ZnO had strong and dose-dependent effects on ileal bacterial community composition and activity, suggesting taxonomic variation in metabolic response to ZnO.
authors.affiliation: Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Pieper
authors.forename: W
authors.initials: W
authors.lastname: Vahjen
authors.forename: K
authors.initials: K
authors.lastname: Neumann
authors.forename: A G
authors.initials: AG
authors.lastname: Van Kessel
authors.forename: J
authors.initials: J
authors.lastname: Zentek
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D004032:Diet / Q000662:veterinary*; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects; D005232:Fatty Acids, Volatile / Q000378:metabolism; D007082:Ileum / Q000382:microbiology* / Q000502:physiology; D019344:Lactic Acid / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D013552:Swine / Q000502:physiology*; D015034:Zinc Oxide / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D004269:DNA, Bacterial; D005232:Fatty Acids, Volatile; D000644:Quaternary Ammonium Compounds; D019344:Lactic Acid; D015034:Zinc Oxide