A mixture of quebracho and chestnut tannins drives butyrate-producing bacteria populations shift in the gut microbiota of weaned piglets

Abstract

Weaning is a critical period for piglets, in which unbalanced gut microbiota and/or pathogen colonisation can contribute to diseases that interfere with animal performance. Tannins are natural compounds that could be used as functional ingredients to improve gut health in pig farming thanks to their antibacterial, antioxidant, and antidiarrhoeal properties. In this study, a mixture of quebracho and chestnut tannins (1.25%) was evaluated for its efficacy in reducing the negative weaning effects on piglet growth. Microbiota composition was assessed by Illumina MiSeq 16S rRNA gene sequencing of DNA extracted from stools at the end of the trial. Sequence analysis revealed an increase in the genera Shuttleworthia, Pseudobutyrivibrio, Peptococcus, Anaerostipes, and Solobacterium in the tannin-supplemented group. Conversely, this dietary intervention reduced the abundance of the genera Syntrophococcus, Atopobium, Mitsuokella, Sharpea, and Prevotella. The populations of butyrate-producing bacteria were modulated by tannin, and higher butyrate concentrations in stools were detected in the tannin-fed pigs. Co-occurrence analysis revealed that the operational taxonomic units (OTUs) belonging to the families Veillonellaceae, Lachnospiraceae, and Coriobacteriaceae occupied the central part of the network in both the control and the tannin-fed animals. Instead, in the tannin group, the OTUs belonging to the families Acidaminococcaceae, Alcaligenaceae, and Spirochaetaceae characterised its network, whereas Family XIII Incertae Sedis occupied a more central position than in the control group. Conversely, the presence of Desulfovibrionaceae characterised the network of the control group, and this family was not present in the network of the tannin group. Moreover, the prediction of metabolic pathways revealed that the gut microbiome of the tannin group possessed an enhanced potential for carbohydrate transport and metabolism, as well as a lower abundance of pathways related to cell wall/membrane/envelope biogenesis and inorganic ion transport. In conclusion, the tested tannins seem to modulate the gut microbiota, favouring groups of butyrate-producing bacteria.

Fig 1

(A) Principal coordinate analysis (PCoA) plot based on Bray–Curtis distances of the intestinal microbial communities of weaning piglets fed on a diet with tannin (TAN) and the control group receiving a basal diet (CTR). (B) Observed species index (p = 0.03), (C) Shannon index (p = 0.02), and (D) Simpson index (p = 0.001). The index values are graphically presented by box plots, each of which represents the interquartile range, whereas the line inside the box represents the median.

Fig 2. Relative abundances of phyla (A), families (B), and genera (C) observed in the tannin-supplemented group (TAN) compared with those of the control group (CTR).

Only the top taxa are represented in the graphs.

Fig 3. Relative abundance of fecal bacterial populations at phylum (A), family (B) and genus (C) levels in tannin-fed (TAN) and control (CTR) piglets.

Only taxa with a mean relative abundance higher than 0.002% are shown. p value significance levels were reported as * p ≤ 0.05; ** p ≤ 0.01; *** p ≤ 0.001.

Fig 4. The most discriminant genera between the control- and tannin-sample sequences as sorted by Random Forest analysis using the mean decrease in accuracy.

Fig 5. Proportion of short-chain fatty acids in control (CTR) and tannin-fed (TAN) piglets.

The * indicates a p value ≤0.05.

Fig 6. SparCC co-occurrence network analysis at the family level of the control (A) and the tannin (B) group microbiota.

The node size represents the relative abundance of families. Lines represent correlations between the nodes they connect. The green colour of an edge indicates positive correlations, whereas the red colour denotes negative correlations. The colour intensity and line thickness indicate the correlation magnitude. Only significant correlations (p < 0.05) are shown.

Fig 7. Significant different orthologous groups of proteins between the tannin (TAN) and control (CTR) piglets.

p value significance levels were reported as * p ≤ 0.05; ** p ≤ 0.01; *** p ≤ 0.001.