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Objectives: This study was aimed to evaluate the effects of dietary supplementation with the microalgae Arthrospira platensis (Ap) and Chlorella vulgaris (Cv) on growth performance, oxidative stress, immune-related cytokines gene expression, cecal fermentation, microbial population, and protein profile changes in growing rabbits. Materials and Methods: Seventy-five male rabbits aged five-week were randomly allocated to five groups (n = 15). The control group received a basal diet without supplementation, whereas the remaining four groups were received basal diets supplemented with Ap or Cv at levels of 300 mg/kg or 500 mg/kg diet for 56 days. Results: Phytochemical analysis revealed that both microalgae were rich in bioactive compounds including flavonoids, terpenoids and tannins exhibiting strong antioxidant activity. Dietary supplementation with Ap and Cv significantly improved BWG and FCR, while decreasing feed consumption. Oxidative stress markers, including malondialdehyde and hydrogen peroxide, were significantly decreased in algal-supplemented groups, accompanied by enhanced antioxidant status. Immune responses were favorably modulated through the upregulation of anti-inflammatory cytokines, particularly (IL-10 and IL-4). In addition, dose-dependent changes in protein expression profiles were observed in serum, liver and spleen tissues. Cecal fermentation parameters were improved, as evidenced by increased total volatile fatty acids, acetic and propionic acids, as well as Lactobacillus spp., along with reduced NH₃-N and pathogenic bacterial populations of E. coli, Staphylococcus spp., Enterococcus spp., and total coliforms (p < 0.05). Conclusions: Dietary supplementation with A. platensis and C. vulgaris improves growth performance, antioxidant capacity, immune function, and cecal health in growing rabbits, supporting their use as feed additives.

Quercetin, a ubiquitous flavonoid, is known to have antibacterial effects. The purpose of this study was to investigate the effect of quercetin on cecal microbiota of Arbor Acre (AA) broiler chickens in vivo and the bacteriostatic effect and antibacterial mechanism of quercetin in vitro. In vivo, 480 AA broilers (1 day old) were randomly allotted to four treatments (negative control and 0.2, 0.4, or 0.6 g of quercetin per kg of diet) for 42 days. Cecal microbial population and distribution were measured at the end of the experiment. The cecal microflora in these broilers included Proteobacteria, Fimicutes, Bacteroidetes, and Deferribacteres. Compared with the negative control, quercetin significantly decreased the copies of Pseudomonas aeruginosa ( P < 0.05), Salmonella enterica serotype Typhimurium ( P < 0.01), Staphylococcus aureus ( P < 0.01), and Escherichia coli ( P < 0.01) but significantly increased the copies of Lactobacillus ( P < 0.01), Bifidobacterium ( P < 0.01), and total bacteria ( P < 0.01). In vitro, we investigated the bacteriostatic effect of quercetin on four kinds of bacteria ( E. coli, P. aeruginosa, S. enterica Typhimurium, and S. aureus) and the antibacterial mechanism of quercetin in E. coli and S. aureus. The bacteriostatic effect of quercetin was stronger on gram-positive bacteria than on gram-negative bacteria. Quercetin damaged the cell walls and membranes of E. coli (at 50 × MIC) and S. aureus (at 10 × MIC). Compared with the control, the activity of the extracellular alkaline phosphatase and β-galactosidase and concentrations of soluble protein in E. coli and S. aureus were significantly increased (all P < 0.01), and the activity of ATP in S. aureus was significantly increased ( P < 0.01); however, no significant change in ATP activity in E. coli was observed ( P > 0.05). These results suggest that quercetin has potential as an alternative antibiotic feed additive in animal production.

IntroductionDue to the anti-inflammatory, antioxidant, and antibacterial properties of olive leaf powder (OLP), it may serve as a beneficial feed supplement for birds. This study aimed to evaluate the effect of adding OLP to feed on growth efficiency, carcass traits, blood parameters, antioxidant activity, and cecal microbial load in growing Japanese quail.MethodsThree hundred and seventy-five one-day-old quail chicks were randomly assigned to five experimental groups, each containing five replicates of 15 birds: a control group fed a basal feed and four experimental groups given 3, 4, 5, and 6% OLP per kg of quail diets for the 6 weeks.ResultsThe results showed a significant (P < 0.05) improvement in growth performance, with increased live body weight (LBW) and an insignificantly improved feed conversion ratio in the 6% OLP group. Carcass yield and total edible meat also substantially improved (P < 0.05). Blood parameters showed improved (P < 0.05) protein and lipid levels and increased liver enzyme activity; moreover, the use of the OLP led to a decrease in TC, TG, LDL, and VLDL levels, as well as an increase in HDL. Additionally, the activity of antioxidant enzymes increased (P < 0.001), along with higher levels of GSH and SOD activity. All meat quality attributes, including cooking loss %, water-holding capacity, PH values, and meat color, improved (P < 0.05) with the use of OLP. Furthermore, intestinal microbiota analysis showed a significant improvement in Lactobacillus count and a decrease in pathogenic bacteria (total bacterial count, coliforms, E. coli, and Salmonella). However, the Bacillus count was not significantly affected by OLP supplementation.DiscussionThe findings of this study demonstrate that OLP is a promising natural feed additive for growing Japanese quail, enhancing growth performance and the gut microbiome, thereby establishing it as a safe and natural growth promoter.

The gastrointestinal microbiota plays a vital role in ensuring the maintenance of host health through interactions with the immune system. The Heterophil/Lymphocyte (H/L) ratio reflects poultry’s robustness and immune system status. Chickens with low H/L ratio are superior to the chickens with high H/L ratio in survival, immune response, and resistance to Salmonella infection, but the underlying mechanisms remain unclear. This study aimed to identify microorganisms associated with resistance to Salmonella Enteritidis infection in chickens based on the H/L ratio. The 16S rRNA and metagenomic analysis were conducted to examine microbiome and functional capacity between the 2 groups, and Short Chain Fatty Acids (SCFAs) and histopathology were conducted to explore the potential difference between susceptible and resistant groups at 7 and 21 days post-infection (dpi). The microbiome exploration revealed that low H/L ratio chickens, compared to high H/L ratio chickens, displayed a significantly higher abundance of Proteobacteria ( Escherichia coli ) and Bacteroidetes ( Bacteroides plebeius ) at 7 and 21 dpi, respectively. Anaerostipes (r = 0.63) and Lachnoclostridium (r = 0.63) were identified as bacterial genus significantly correlated with H/L (P < 0.001). Interestingly, Bacteroides was significantly and positively correlated with bodyweight post-infection (r = 0.72), propionate (r = 0.78) and valerate (r = 0.82) contents, while Salmonella was significantly and negatively correlated with bodyweight post-infection (r = − 0.67), propionate (r = − 0.61) and valerate (r = − 0.65) contents (P < 0.001). Furthermore, the comparative analysis of the functional capacity of cecal microbiota of the chickens with high and low H/L ratio revealed that the chickens with low H/L ratio possess more enriched immune pathways, lower antibiotic resistance genes and virulence factors compared to the chickens with high H/L ratio. These results suggest that the chickens with low H/L ratio are more resistant to Salmonella Enteritidis, and it is possible that the commensal Proteobacteria and Bacteroidetes are involved in this resistance against Salmonella infection. These findings provide valuable resources for selecting and breeding disease-resistant chickens.

Background Improving feed efficiency is the most important goal for modern animal production. The regulatory mechanisms of controlling feed efficiency traits are extremely complex and include the functions related to host genetics and gut microbiota. Short-chain fatty acids (SCFAs), as significant metabolites of microbiota, could be used to refine the combined effect of host genetics and gut microbiota. However, the association of SCFAs with the gut microbiota and host genetics for regulating feed efficiency is far from understood. Results In this study, 464 broilers were housed for RFI measuring and examining the host genome sequence. And 300 broilers were examined for cecal microbial data and SCFA concentration. Genome-wide association studies (GWAS) showed that four out of seven SCFAs had significant associations with genome variants. One locus (chr4: 29414391–29417189), located near or inside the genes MAML3 , SETD7 , and MGST2 , was significantly associated with propionate and had a modest effect on feed efficiency traits and the microbiota. The genetic effect of the top SNP explained 8.43% variance of propionate. Individuals with genotype AA had significantly different propionate concentrations (0.074 vs. 0.131 μg/mg), feed efficiency (FCR: 1.658 vs. 1.685), and relative abundance of 14 taxa compared to those with the GG genotype. Christensenellaceae and Christensenellaceae_R-7_group were associated with feed efficiency, propionate concentration, the top SNP genotypes, and lipid metabolism. Individuals with a higher cecal abundance of these taxa showed better feed efficiency and lower concentrations of caecal SCFAs. Conclusion Our study provides strong evidence of the pathway that host genome variants affect the cecal SCFA by influencing caecal microbiota and then regulating feed efficiency. The cecal taxa Christensenellaceae and Christensenellaceae_R-7_group were identified as representative taxa contributing to the combined effect of host genetics and SCFAs on chicken feed efficiency. These findings provided strong evidence of the combined effect of host genetics and gut microbial SCFAs in regulating feed efficiency traits. 6SQoLRD3ZqDatjTJpeYTJE Video Abstract

Clostridium butyricum (CB) can enhance antioxidant capacity and alleviate oxidative damage, but the molecular mechanism by which this occurs remains unclear. This study used enterotoxigenic Escherichia coli (ETEC) K88 as a pathogenic model, and the p62-Keap1-Nrf2 signaling pathway and intestinal microbiota as the starting point to explore the mechanism through which CB alleviates oxidative damage. After pretreatment with CB for 15 d, mice were challenged with ETEC K88 for 24 h. The results suggest that CB pretreatment can dramatically reduce crypt depth (CD) and significantly increase villus height (VH) and VH/CD in the jejunum of ETEC K88-infected mice and relieve morphological lesions of the liver and jejunum. Additionally, compared with ETEC-infected group, pretreatment with 4.4×10 6 CFU/mL CB can significantly reduce malondialdehyde (MDA) level and dramatically increase superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels in the serum. This pretreatment can also greatly increase the mRNA expression levels of tight junction proteins and genes related to the p62-Keap1-Nrf2 signaling pathway in the liver and jejunum in ETEC K88-infected mice. Meanwhile, 16S rDNA amplicon sequencing revealed that Clostridium disporicum was significantly enriched after ETEC K88 challenge relative to the control group, while Lactobacillus was significantly enriched after 4.4×10 6 CFU/mL CB treatment. Furthermore, 4.4×10 6 CFU/mL CB pretreatment increased the short-chain fatty acid (SCFA) contents in the cecum of ETEC K88-infected mice. Moreover, we found that Lachnoclostridium , Roseburia , Lactobacillus , Terrisporobacter , Akkermansia , and Bacteroides are closely related to SCFA contents and oxidative indicators. Taken together, 4.4×10 6 CFU/mL CB pretreatment can alleviate ETEC K88-induced oxidative damage through activating the p62-Keap1-Nrf2 signaling pathway and remodeling the cecal microbiota community in mice.

Background Eimeria spp. are responsible for chicken coccidiosis which is the most important enteric protozoan disease resulting in tremendous economic losses in the poultry industry. Understanding the interaction between the avian cecal microbiota and coccidia is of interest in the development of alternative treatments that do not rely on chemotherapeutics and do not lead to drug resistance. Methods We utilized 16S rRNA gene sequencing to detect the dynamics of the cecal microbial community in AA broilers challenged with Eimeria tenella . Histopathological analysis of the cecum was also conducted. Results We found that microbial shifts occur during the infection. Lactobacillus , Faecalibacterium , Ruminococcaceae UCG-013, Romboutsia and Shuttleworthia decreased in abundance. However, the opportunistic pathogens Enterococcus and Streptococcus increased in abundance over time in response to the infection. Conclusions Eimeria tenella disrupts the integrity of the cecal microbiota and could promote the establishment and growth of potentially pathogenic bacteria. Defining bacterial populations affected by coccidial infection might help identify bacterial markers for intestinal disease as well as populations or species that could be beneficial in maintaining and restoring gut homeostasis during and after infection with E. tenella .

Improving growth performance is vital in poultry production. Although several studies have established associations between gut microbiota and growth, the direct impacts remain unclear. A total of 120 1-day-old Sansui ducks were randomly assigned to the FMT and CON groups. From the 1st day, ducks in the FMT group were orally administrated with 0.5 mL fecal microbiota suspension for three consecutive days, while sterile PBS solution was used as a substitute in the CON group. The results revealed that FMT improved average daily gain (ADG) ( P  < 0.001) and body weight (BW) ( P  < 0.001), with a tendency for a better feed conversion rate (FCR) ( P  = 0.062). LEfSe analysis indicated a significant increase in the abundance of the Lactobacillus ( P  < 0.001), Bifidobacterium ( P  = 0.006), Megamonas ( P  = 0.008), and Subdoligranulum ( P  = 0.005) in the FMT group. Similarly, the phyla Firmicutes/Bacteroidetes ratio was higher in the FMT group compared to the CON group. Additionally, the ACE, Chao, and Shannon indices were also significantly higher in the FMT group ( P  < 0.001). To sum up, FMT enhanced growth performance, which could be associated with reducing proinflammatory pathogen colonization in the duck cecum. This modulating effect likely results from increased microbial diversity and the enrichment of beneficial bacteria.

Background The chicken gut microbiota is an important and complicated ecosystem for the host. They play an important role in converting food into nutrient and energy. The coding capacity of microbiome vastly surpasses that of the host’s genome, encoding biochemical pathways that the host has not developed. An optimal gut microbiota can increase agricultural productivity. This study aims to explore the composition and function of cecal microbiota in Dagu chicken under two feeding modes, free-range (outdoor, OD) and cage (indoor, ID) raising. Results Cecal samples were collected from 24 chickens across 4 groups (12-w OD, 12-w ID, 18-w OD, and 18-w ID). We performed high-throughput sequencing of the 16S rRNA genes V4 hypervariable regions to characterize the cecal microbiota of Dagu chicken and compare the difference of cecal microbiota between free-range and cage raising chickens. It was found that 34 special operational taxonomic units (OTUs) in OD groups and 4 special OTUs in ID groups. 24 phyla were shared by the 24 samples. Bacteroidetes was the most abundant phylum with the largest proportion, followed by Firmicutes and Proteobacteria. The OD groups showed a higher proportion of Bacteroidetes (>50 %) in cecum, but a lower Firmicutes/Bacteroidetes ratio in both 12-w old (0.42, 0.62) and 18-w old groups (0.37, 0.49) compared with the ID groups. Cecal microbiota in the OD groups have higher abundance of functions involved in amino acids and glycan metabolic pathway. Conclusion The composition and function of cecal microbiota in Dagu chicken under two feeding modes, free-range and cage raising are different. The cage raising mode showed a lower proportion of Bacteroidetes in cecum, but a higher Firmicutes/Bacteroidetes ratio compared with free-range mode. Cecal microbiota in free-range mode have higher abundance of functions involved in amino acids and glycan metabolic pathway.

Gut microbiota regulates broilers’ gastrointestinal functions, digestion, metabolism, and immune responses. Modulating the microbiota in the early stage could present a promising approach for the poultry industry. Embryonic thermal manipulation (TM) constitutes a promising strategy for sustainable broiler production. Our previous research has yielded significant insights into the impact of TM on embryonic thermotolerance, metabolism, post-hatch growth performance, microbial diversity, and immunity. This follow-up study utilized a subset of birds from our previous study to investigate the effects of TM on early cecal microbiota composition, predicted metabolic pathways, and ileum immunity-related genes. A total of 600 fertile Cobb 500 eggs were incubated for 21 d. After candling, 238 eggs underwent TM at 38.5 °C with 55% relative humidity (RH) from embryonic day (ED) 12 to 18, then were transferred to a hatcher at 37.5 °C from ED 19 to 21, while 236 eggs were incubated at 37.5 °C throughout until 21 d. After hatching, 60-day-old unsexed chicks were housed in 12 pens (10 birds/pen, 6 replicates per treatment). The treatments included 1) Control and 2) TM. All birds were raised under standard conditions (22-24 °C) for the first 21 d. This study evaluated the effects of embryonic TM on four parameters: the composition of cecal microbiota (relative abundance at multiple taxonomic levels), microbial diversity indices (both alpha and beta diversity), predicted microbial metabolic pathways, and the expression of ileal immune-related genes on days 7, 14, and 21. TM significantly increased ( P  < 0.05) microbial beta diversity (Bray-Curtis, Jaccard and, unweighted UniFrac) and metabolic microbial pathways at days 7, 14, and 21. In the ileum, at d 7, the mRNA expression of IL10, IL12 , IL18, TLR1, TLR2A, TLR4, TLR21, TBK1, TGFb, TGFb3, IFNg , NFkB, and CD3 was significantly lower ( P  < 0.05) in the TM group compared to the Control group. There was no significant difference ( P  < 0.05) between the treatment groups at d 14. However, at d 21, IL4, IL6, AvBD6, and IFNg were significantly lower ( P  < 0.05), and TLR2A and TGFb3 expression were significantly higher ( P  < 0.05) in the TM group compared to the Control group. Embryonic TM significantly increased cecal microbial diversity and predicted metabolic pathways, thereby improving ileum immunity in the early stages of life in broiler chickens.