Intestinal microbiota modulation and improved growth in pigs with post-weaning antibiotic and ZnO supplementation but only subtle microbiota effects with Bacillus altitudinis

Abstract

The objective was to evaluate the effect of dietary Bacillus altitudinis spore supplementation during day (D)0-28 post-weaning (PW) and/or D29-56 PW compared with antibiotic and zinc oxide (AB + ZnO) supplementation on pig growth and gut microbiota. Eighty piglets were selected at weaning and randomly assigned to one of five dietary treatments: (1) negative control (Con/Con); (2) probiotic spores from D29-56 PW (Con/Pro); (3) probiotic spores from D0-28 PW (Pro/Con); (4) probiotic spores from D0-56 PW (Pro/Pro) and (5) AB + ZnO from D0-28 PW. Overall, compared with the AB + ZnO group, the Pro/Con group had lower body weight, average daily gain and feed intake and the Pro/Pro group tended to have lower daily gain and feed intake. However, none of these parameters differed between any of the probiotic-treated groups and the Con/Con group. Overall, AB + ZnO-supplemented pigs had higher Bacteroidaceae and Prevotellaceae and lower Lactobacillaceae and Spirochaetaceae abundance compared to the Con/Con group, which may help to explain improvements in growth between D15-28 PW. The butyrate-producing genera Agathobacter, Faecalibacterium and Roseburia were more abundant in the Pro/Con group compared with the Con/Con group on D35 PW. Thus, whilst supplementation with B. altitudinis did not enhance pig growth performance, it did have a subtle, albeit potentially beneficial, impact on the intestinal microbiota.

Figure 1

Shannon α-diversity of the faecal microbiota of pigs supplemented with Bacillus altitudinis WIT588 spores during 1st stage and/or 2nd stage weaning or with antibiotic (AB) + ZnO during 1st stage weaning or un-supplemented during both stages. Treatments (1st stage weaning period/2nd stage weaning period) are as follows: Con/Con, Con/Pro, Pro/Con, Pro/Pro, and AB + ZnO; where Con = control, Pro = probiotic and AB + ZnO = antibiotic + ZnO. Colours indicate the time point post-weaning at which pigs were sampled. Significant differences between treatments within each sampling time point are indicated as ** (P ≤ 0.01), * (0.01 < P ≤ 0.05) and † (0.05 < P ≤ 0.1).

Figure 2

(A) PCoA plot of the Bray Curtis distances of the faecal microbiota of pigs on all five treatments across all sampling time points. (B–F) PCA plots of the intergroup variation for amplicon sequence variant (ASV) representation at the genus level of the faecal microbiota of Con/Con and AB + ZnO treatments during five time points post-weaning (PW): (B) Day 13 PW, (C) Day 27 PW, (D) Day 35 PW, (E) Day 55 PW, and (F) Day 100 PW. Shapes indicate the day PW that pigs were sampled. Colours indicate the treatments as follows (1st stage weaning period/2nd stage weaning period): Con/Con, Con/Pro, Pro/Con, Pro/Pro, and AB + ZnO; where Con = control, Pro = probiotic and AB + ZnO = antibiotic + ZnO.

Figure 3

Phylogenetic trees showing pairwise comparisons of the relative abundances of all bacterial families (including those at < 1% relative abundance) within the faecal microbiota between treatments at D27 post-weaning (treatments indicated along the top of the figure are compared with those listed down the right-hand side). Taxa that are relatively more abundant in the treatments indicated at the top of the figure compared to those on the right are indicated in brown, while those that are less abundant are shown in green. The colour gradient indicates the difference in fold change between treatments for the relative abundance of a certain taxon. Treatments (1st stage weaning period/2nd stage weaning period) are as follows: Con/Con, Con/Pro, Pro/Con, Pro/Pro, and AB + ZnO; where, Con = control; Pro = probiotic and AB + ZnO = antibiotic + ZnO.

Figure 4

Mean relative abundances (%) of bacterial phyla (A), 20 most abundant families (B), and 20 most abundant genera (C) within the faeces of pigs across all sampling days and treatments (n = 262). Treatments are as follows (1st stage weaner period/2nd stage weaner period): Con/Con, Con/Pro, Pro/Con, Pro/Pro, and AB + ZnO; where Con = control; Pro = probiotic and AB + ZnO = antibiotic + ZnO.