Effect of riboflavin deficiency on intestinal morphology, jejunum mucosa proteomics, and cecal microbiota of Pekin ducks

Respiratory Exposure to Agriculture Dust Extract Alters Gut Commensal Species and Key Metabolites in Mice

Exposure to agricultural dust containing antimicrobial-resistant pathogens poses significant health risks for workers in animal agriculture production. Beyond causing severe airway inflammation, pollutants are linked to intestinal diseases. Swine farm dust is rich in ultrafine particles, gram-positive and gram-negative bacteria, and bacterial components such as lipopolysaccharides (LPS; endotoxins). In our previous study, we demonstrated that intranasal exposure of male and female C57BL/6J mice to 12.5% hog dust extract (HDE, containing 22.1-91.1 EU/mL) for 3 weeks resulted in elevated total cell and neutrophil counts in bronchoalveolar lavage fluid and increased intestinal permeability compared to saline controls. Now, we report that 16S and metagenomic analyses of Week 3 stool samples from HDE-treated mice indicate a reduced abundance of the beneficial species Akkermansia muciniphila and Clostridium sp. ASF356 and Lachnospiraceae bacterium. Bacterial alpha diversity showed increased species evenness in fecal samples from HDE-treated mice (Pielou's evenness, p = 0.047, n = 5-6/group). Metabolomic analysis also indicated significant reductions in key metabolites involved in energy metabolism, including riboflavin (p = 0.027, n = 11) and nicotinic acid (p = 0.049, n = 11), as well as essential amino acids, such as inosine (p = 0.043, n = 11) and leucine (p = 0.018, n = 11). While HDE exposure does not robustly alter overall microbial abundance or community structure, it leads to specific reductions in beneficial bacterial species and critical metabolites necessary for maintaining intestinal homeostasis by supporting energy metabolism, gut barrier function, microbiota balance, and immune regulation. The results of this study underscore the potential risks for gut health posed by inhalation of agricultural dust.

Phloretin supplementation ameliorates intestinal injury of broilers with necrotic enteritis by alleviating inflammation, enhancing antioxidant capacity, regulating intestinal microbiota, and producing plant secondary metabolites

The present study aimed to explore the effects of dietary phloretin (PT) on growth performance, immune response, and intestinal function in broilers with necrotic enteritis (NE). A total of 288 1-day-old Arbor Acres chicks were assigned to 3 groups, with 8 replicates per group and 12 chicks per replicate. Over 6 weeks, birds were fed a basal diet or the same diet supplemented with 200 mg/kg phloretin. Birds in the challenged groups were inoculated with coccildia during d 7 to 9 and Clostridium perfringens(CP) during d 14 to 18. Results showed that CP and coccidia challenge reduced the average daily gain and average daily feed intake, increased the feed conversion ratio of broilers, induced inflammation and oxidative stress, and inhibited mRNA expression levels for genes associated with intestinal barrier and nutrient transporters (P < 0.05). PT addition to the feed improved growth performance at early phase improved intestinal morphology, and elevated antioxidant capacity via increasing the activity of total antioxidant capacity and superoxide dismutase in the ileum in broilers with necrotic enteritis (P < 0.01). Dietary PT regulated the intesetinal immune function as observed by the increases in the content of secretory IgA in the ileum and decreased cytokines (Interleukin-1β, Interleukin-10) (P < 0.05). Moreover, NE infection significantly disrupted the balance of intestinal flora, and led to a lower level of short-chain fatty acids such as butyric acid concentration in the ileum, while PT improved the microbiota structure, and increased the intestinal acetic acid and butyric acid concentration (P < 0.001). Furthermore, metabolomics analysis indicated PT treatment improve plant secondary metabolites contents like phloretin 2'-o-glucuronide. Additionally, we observed a significant positive correlation among PT, Ligilactobacillus and butyric acid, and a positive correlation between Ligilactobacillus and plant secondary metabolites. Overall, PT supplementation could improve growth performance and ameliorate intestinal injury in broilers with necrotic enteritis by enhancing the antioxidant capacity and immune function, regulating intestinal flora structure and producing plant secondary metabolites.

Riboflavin ameliorates intestinal inflammation via immune modulation and alterations of gut microbiota homeostasis in DSS-colitis C57BL/6 mice

While there have been advancements in understanding the direct and indirect impact of riboflavin (B2) on intestinal inflammation, the precise mechanisms are still unknown. This study focuses on evaluating the effects of riboflavin (B2) supplementation on a colitis mouse model induced with 3% dextran sodium sulphate (DSS). We administered three different doses of oral B2 (VB2L, VB2M, and VB2H) and assessed its impact on various physiological and biochemical parameters associated with colitis. Mice given any of the three doses exhibited relative improvement in the symptoms and intestinal damage. This was evidenced by the inhibition of the pro-inflammatory cytokines TNF-α, IL-1β, and CALP, along with an increase in the anti-inflammatory cytokine IL-10. B2 supplementation also led to a restoration of oxidative homeostasis, as indicated by a decrease in myeloperoxidase (MPO) and malondialdehyde (MDA) levels and an increase in reduced glutathione (GSH) and catalase (CAT) activities. B2 intervention showed positive effects on intestinal barrier function, confirmed by increased expression of tight junction proteins (occludin and ZO-1). B2 was linked to an elevated relative abundance of Actinobacteriota, Desulfobacterota, and Verrucomicrobiota. Notably, Verrucomicrobiota showed a significant increase in the VB2H group, reaching 15.03% relative abundance. Akkermansia exhibited a negative correlation with colitis and might be linked to anti-inflammatory function. Additionally, a remarkable increase in n-butyric acid, i-butyric acid, and i-valeric acid was reported in the VB2H group. The ameliorating role of B2 in gut inflammation can be attributed to immune system modulation as well as alterations in the gut microbiota composition, along with elevated levels of fecal SCFAs.

High-Throughput Sequencing Reveals a Dynamic Bacterial Linkage between the Captive White Rhinoceros and Its Environment

Soil is an essential part of the animal habitat and has a large diversity of microbiota, while the animal body was colonized by a complex bacterial community; so far, the relationship between the animal host microbial community and the soil microbial ecosystem remains largely unknown. In this study, 15 white rhinoceros from three different captive grounds were selected and the bacterial community of the gut, skin, and environment of these rhinoceros were analyzed by 16S rRNA sequencing technology. Our results showed that Firmicutes and Bacteroidota were the predominant phyla in the gut microbiome, whereas skin and environment samples share similar microbiome profiles and are dominated by the phyla of Actinobacteriota, Chloroflexi, and Proteobacteria. Although the bacterial composition of the gut differs from that of the skin and environment, the Venn diagrams showed that there were 22 phyla and 186 genera shared by all the gut, skin, and environmental microbes in white rhinoceroses. Further cooccurrence network analysis indicated a bacterial linkage based on a complex interaction was established by the bacterial communities from the three different niches. In addition, beta diversity and bacterial composition analysis showed that both the captive ground and host ages induced shifts in the microbial composition of white rhinoceroses, which suggested that the bacterial linkage between the captive white rhinoceros and its environment is dynamic. Overall, our data contribute to a better understanding of the bacterial community of the captive white rhinoceros, especially for the relationship between the environment and animal bacterial communities. IMPORTANCE The white rhinoceros is one of the world's most endangered mammals. The microbial population plays a key role in animal health and welfare; however, studies regarding the microbial communities of the white rhinoceros are relatively limited. As the white rhinoceros has a common behavior of mud baths and thus is in direct contact with the environment, a relationship between the animal microbial community and the soil microbial ecosystem appears possible, but it remains unclear. Here, we described the characteristics and interaction of bacterial communities of the white rhinoceros in three different niches, including gut, skin, and environment. We also analyzed the effects of captive ground and age on the composition of the bacterial community. Our findings highlighted the relationship among the three niches and may have important implications for the conservation and management of this threatened species.

Assessing the effects of a mixed Eimeria spp. challenge on performance, intestinal integrity, and the gut microbiome of broiler chickens

A mixed Eimeria spp. challenge model was designed to assess the effects of challenge on broiler chicken performance, intestinal integrity, and the gut microbiome for future use to evaluate alternative strategies for controlling coccidiosis in broiler chickens. The experimental design involved broiler chickens divided into two groups: a control group (uninfected) and a positive control group, infected with Eimeria acervulina (EA), Eimeria maxima (EM), and Eimeria tenella (ET). At day-of-hatch, 240 off-sex male broiler chicks were randomized and allocated to one of two treatment groups. The treatment groups included: (1) Non-challenged (NC, n = 5 replicate pens); and (2) challenged control (PC, n = 7 replicate pens) with 20 chickens/pen. Pen weights were recorded at d0, d16, d31, d42, and d52 to determine average body weight (BW) and (BWG). Feed intake was measured at d16, d31, d42, and d52 to calculate feed conversion ratio (FCR). Four diet phases included a starter d0-16, grower d16-31, finisher d31-42, and withdrawal d42-52 diet. At d18, chickens were orally challenged with 200 EA, 3,000 EM, and 500 ET sporulated oocysts/chicken. At d24 (6-day post-challenge) and d37 (19-day post-challenge), intestinal lesion scores were recorded. Additionally, at d24, FITC-d was used as a biomarker to evaluate intestinal permeability and ileal tissue sections were collected for histopathology and gene expression of tight junction proteins. Ileal and cecal contents were also collected to assess the impact of challenge on the microbiome. BWG and FCR from d16-31 was significantly (p < 0.05) reduced in PC compared to NC. At d24, intestinal lesion scores were markedly higher in the PC compared to the NC. Intestinal permeability was significantly increased in the PC group based on serum FITC-d levels. Cadherin 1 (CDH1), calprotectin (CALPR), and connexin 45 (Cx45) expression was also upregulated in the ileum of the PC group at d24 (6-day post-challenge) while villin 1 (VIL1) was downregulated in the ileum of the PC group. Additionally, Clostridium perfringens (ASV1) was enriched in the cecal content of the PC group. This model could be used to assess the effect of alternative coccidiosis control methods during the post-challenge with EA, EM, and ET.