Early social contact alters the community structure and functions of the faecal microbiome in suckling-growing piglets

From mother to piglet: the lasting influence of the maternal microbiome

BACKGROUND

Given their crucial roles in agriculture and biomedical research, promoting pig health is essential. A balanced gut microbiota is vital for immune development, metabolism and pathogen resistance, and requires optimal initial colonization by beneficial bacteria. This becomes particularly evident during early life stages, like suckling and weaning, where disruptions can lead to long-term health issues. Understanding the factors influencing microbiome development during these phases is fundamental for enhancing pig health. On these basis, rectal swab samples from eighteen sow-piglet pairs were collected at multiple time points from 7 days after birth to 10 days post-weaning, and analyzed through 16S rRNA gene sequencing. This study aims to understand the maternal influence on piglet microbiota development during the suckling-weaning period, exploring microbial diversity, composition and additional influencing factors such as age, piglet and weaning.

RESULTS

α diversity significantly increased with piglet age (p < 0.001) and stabilized upon weaning, with maternal influence and differences between individual piglet affecting variability before weaning. Post-weaning α diversity was influenced by the pen environment (contributing to 14.5-16% of the variability between piglets) rather than age. Both the sow (~ 9.6%) and age of the piglets (20-30%) had a significant impact on the microbial β diversity over the entire timeframe. Moreover, at 10 days post-weaning a significant influence of the cage mates on piglets microbial β diversity was observed (~ 24.6%). Source-tracking analysis revealed a significant maternal contribution to piglet microbiome at 7 days (31.68%), which decreased over time but remained at 13.33% post-weaning. Piglet microbiome exhibited consistency across time, with 22.55-61.23% of bacteria retained from previous stages. Cage mates contributed 53.54% to the microbiome at 10 days post-weaning. Additionally, 68.32% of piglets microbiome at 7 days was derived from sources not included in the study, decreasing to 37.6% by 10 days post-weaning. ASV-level analysis showed that the majority of maternally transmitted ASVs pre-weaning persisted until the last time point, with both beneficial bacteria and pathobionts being transmitted.

CONCLUSIONS

This study highlights the significant influence of maternal microbiota on piglet gut microbiome development, affecting both diversity and composition. Beneficial bacteria are transmitted from mothers to offspring and persist through early developmental stages, thereby emphasizing the long-lasting impact of maternal microbiome and the importance of early microbial colonization for piglet health.

Effects of dustbathing environment on gut microbiota and expression of intestinal barrier and immune-related genes of adult laying hens housed individually in modified traditional cage

Litters, the composition of sand and peat rich in microbiota, are essential to trigger the dustbathing behavior of chickens. To investigate the effects of a dustbathing environment (DE) on the intestinal health, gut microbiota, and immune responses of laying hens, a total of 72 healthy Hy-Line Brown laying hens at 69 wk of age (WOA) were housed individually in modified traditional cages and randomly divided into 2 groups: one group had free access to litters (CT), while the other one was restricted from litters (CC). The experiment lasted for 42 d. At the end of the experiment, the intestinal histomorphology and immune status of laying hens were determined, and the 16S rRNA sequencing method was used to assess the composition of the intestinal microbial community of birds. Intestinal histomorphology changed, including villus height and villus-to-crypt ratio significantly increased in the CT group (P < 0.01). DE reshaped the microbial community and increased the microbial richness with the higher indicators of Chao1 and observed species and the comparatively abundant beta diversity (P < 0.05). Ten genera, including Faecalibacterium and Coprococcus, declined in laying hens from the CT group (P < 0.05), while Alistipes increased in CT hens (P < 0.05) compared to those hens from the CC group. The expression levels of intestinal barrier-related genes of claudin-1, claudin-4, occludin, ZO-1, and ZO-2 and immune-related genes of IL-4, IL-6, IL-8, IFN-γ, IgA, TLR-2, and TLR-4 were significantly upregulated in the intestine of laying hens in CT group (P < 0.05). DE also increased the serum levels of IL-4, IL-6, IL-8, IFN-γ, and IgA (P < 0.01). The alteration of the gut microbiota by DE is closely related to host immune responses, including Lactobacillus positively correlated with IL-4 and IgA. Thus, a dustbathing environment can improve the welfare of laying hens by changing the intestinal histomorphology, immune response, and the gut microbial community.

Effects of improved early-life conditions on health, welfare, and performance of pigs raised on a conventional farm

Nowadays, most pigs are raised indoors, on intensive farms providing a poor environment. In these conditions, the risk of the occurrence of damaging behaviours is high, with dramatic consequences for animal health and welfare as well as economic losses for farmers. Early-life conditions may predispose individuals to develop damaging behaviours later in life. In contrast, reinforcing affiliative behaviours between piglets before weaning might help to prevent tail-biting episodes. In this field study, we aimed at improving early-life conditions of piglets on a commercial farm by completely suppressing painful procedures and staggering their exposure to weaning stress factors. The alternative early-life management strategy combined housing in free-farrowing pens with temporary crating of the sow, socialisation during the lactation period with whole-life maintenance of the hierarchical groups, and delayed transfer to the postweaning room after sow removal. Control conditions included birth in farrowing crates, tail docking, absence of socialisation during the lactation period, abrupt weaning with immediate transfer to the postweaning room and mixing with non-littermates. We evaluated the health, welfare, and performance of alternatively raised pigs (n = 80) as compared to controls (n = 75). Visits were made throughout the lifespan of individuals to evaluate their growth and health status. Body and tail lesions were scored as proxy measures of aggressiveness and impaired welfare. Blood and bristle samples were periodically collected to evaluate stress, inflammation and immune competence. While the whole-life performance of pigs was similar among groups, the alternative early-life conditions prevented the growth slowdown usually observed after weaning. In addition, alternatively raised pigs displayed more neutrophils, eosinophils and monocytes the day after weaning, as well as higher C-Reactive Protein levels. One week later, their monocytes displayed greater phagocytic capacity. Altogether, these data suggest an enhanced innate immune competence for alternatively raised pigs around weaning. Piglets reared under alternative conditions also exhibited fewer and less severe body lesions than standard pigs, one week after weaning. In contrast, they showed more tail lesions on days 36 and 66 associated with greater levels of acute phase proteins (C-Reactive Protein and haptoglobin). To conclude, alternative early-life management better prepared piglets for weaning. However, the whole-life maintenance of early-established social groups was not sufficient to prevent the occurrence of damaging behaviours in undocked pigs.

Socializing Models During Lactation Alter Colonic Mucosal Gene Expression and Fecal Microbiota of Growing Piglets

The enrichment of the social environment during lactation alleviates the stress of weaned piglets. It is significant to understand how the enriched social environment improves the weaning stress of piglets. RNA sequencing (RNA-seq) of colonic mucosa, 16S rRNA sequencing of feces, and short-chain fatty acids (SCFAs) of colonic content were used to determine the effects of social contact during lactation. In this study, thirty litter lactating piglets were divided into intermittent social contact (ISC) group that contacted with neighbors intermittently, continuous social contact (CSC) group that contacted with neighbors starting at day (D) 14 after birth, and control (CON) group in which piglets were kept in their original litter. The piglets were weaned at D35 and regrouped at D36. The colonic mucosal RNA-seq, fecal microbes, and SCFAs of colonic contents of 63-day-old piglets were analyzed. The results of RNA-seq showed that compared with the CON group, the pathways of digestion and absorption of minerals, protein, and vitamins of piglets were changed in the ISC group, whereas the pathways of retinol metabolism and nitrogen metabolism in the colonic mucosal were affected and stimulated the immune response in the CSC group. Compared with the CON group, the abundances of pernicious microorganisms (Desulfovibrio, Pseudomonas, Brevundimonas, etc.) in the CSC group and pernicious microorganisms (Desulfovibrio, Neisseria, Sutterella, etc.) and beneficial bacteria (Bifidobacterium, Megamonas, and Prevotella_9) in the ISC group were significantly higher (p < 0.05). The abundances of proinflammatory bacteria (Coriobacteriaceae_unclassified, Coprococcus_3, and Ruminococcus_2) in the CSC group were significantly increased (p < 0.05), but the abundances of SCFAs producing bacteria (Lachnospiraceae_UCG-010, Parabacteroides, Anaerotruncus, etc.) and those of anti-inflammatory bacteria (Eubacterium, Parabacteroides, Ruminiclostridium_9, and Alloprevotella) were significantly reduced (p < 0.05) in the CSC group. Compared with the CON group, the concentrations of microbial metabolites, acetate, and propionate in the colonic contents were reduced (p < 0.05) in the ISC group, whereas the concentration of acetate was reduced (p < 0.05) in the CSC group. Therefore, both ISC and CSC during lactation affected the composition of fecal microbes and changed the expression of intestinal mucosal genes related to nutrient metabolism and absorption of piglets.