Increased dietary zinc oxide changes the bacterial core and enterobacterial composition in the ileum of piglets

Abstract

This study was conducted to investigatethe effects of increased dietary ZnO on the bacterialcore and enterobacterial composition in the smallintestine of piglets that were fed diets containing a totalof 124 or 3,042 mg of Zn per kilogram of diet, respectively.Zinc was supplemented to the basal diet asZnO. Bacterial 16S rRNA genes of ileal DNA extractswere PCR-amplified with 2 bar-coded primer sets andsequenced by 454 pyrosequencing. The bacterial corespecies were calculated from the relative abundances ofreads present in 5 of 6 samples per group and at a minimumof 5 sequences per sample. The reference databaseSILVA was used to assign sequence reads at an alignmentminimum of 200 bases and 100% identity. Lacticacid bacteria dominated the bacterial core, but showeddiverse responses to dietary ZnO. Of the dominant Lactobacillusspp., Lactobacillus reuteri was reduced dueto increased dietary ZnO (44.7 vs. 17.9%; P = 0.042),but L. amylovorus was not influenced. However, thechanges of relative abundances of other lactic acid bacteriawere more noteworthy; Weissella cibaria (10.7 vs.23.0%; P = 0.006), W. confusa (10.0 vs. 22.4%; P = 0.037), Leuconostoc citreum (6.5 vs. 14.8%; P = 0.009),Streptococcus equinus (0.14 vs. 1.0%; P = 0.044), andS. lutetiensis (0.01 vs. 0.11%; P = 0.016) increased inrelative abundance. Nonlactic acid bacteria that wereinfluenced by increased dietary ZnO included the strictanaerobic species, Sarcina ventriculi, which showed astrong numerical decrease in relative abundance (14.6vs. 5.1%). Species of the Enterobacteriaceae increasedtheir relative abundance, as well as species diversity, inthe high dietary ZnO experimental group. Bacterial diversityindices were increased due to increased dietaryZnO (P < 0.05), which was traced back to the increaseof sequences from subdominant species. Increased dietaryZnO led to an increase of less prominent speciesand, thus, had a major impact on the bacterial compositionand diversity in piglets. This effect may helpto stabilize the intestinal microbiota in the sensitivepostweaning period. © 2011 American Society of Animal Science. All rights reserved.