Poultry fed on wheat-based diets regularly ingest wheat germ agglutinin (WGA) that has toxic effects in vitro on intestinal epithelial cells (IEC) obtained from 14-d-old broilers. Cytotoxicity and the potential role of 14 intestinal bacterial strains in the removal of bound lectins in epithelial cell cultures were investigated. Cytotoxicity was dependent on time and lectin concentration; the lethal dose (LD) was 8.36 µg/ml for IEC exposed for 2 h to WGA. Complementary sugars to WGA were detected on the surface of one Enterococcus and 9 Lactobacillus strains isolated from poultry. These strains were evaluated as a lectin removal tool for cytotoxicity prevention. Incubation of lactic acid bacteria with WGA before IEC-lectin interaction caused a substantial reduction in the percentage of cell deaths. The protection was attributed to the amount of lectin bound to the bacterial surfaces and was strain-dependent. L. salivarius LET 201 and L. reuteri LET 210 were more efficient than the other lactic acid bacteria assayed. These results provide a basis for the development of probiotic supplements or cell-wall preparations of selected lactic acid bacteria intended to avoid harmful effects of a natural constituent of the grain in wheat-based diets.

The gut microbiota is viewed as the "second genome" of animals, sharing intricate relationships with their respective hosts. Because the gut microbial community and its diversity are affected by many intrinsic and extrinsic factors, studying intestinal microbes has become an important research topic. However, publications are dominated by studies on domestic or captive birds, while research on the composition and response mechanism of environmental changes in the gut microbiota of wild birds remains scarce. Therefore, it is important to understand the co-evolution of host and intestinal bacteria under natural conditions to elucidate the diversity, maintenance mechanisms, and functions of gut microbes in wild birds. Here, the existing knowledge of gut microbiota in captive and wild birds is summarized, along with previous studies on the composition and function, research methods employed, and factors influencing the avian gut microbial communities. Furthermore, research hotspots and directions were also discussed to identify the dynamics of the avian gut microbiota, aiming to contribute to studies of avian microbiology in the future.

The present study investigated the effect of Bacillus subtilis DSM 29784 (Ba) and enzymes (xylanase and β-glucanases; Enz), alone or in combination (BE) as antibiotic replacements, on the growth performance, digestive enzyme activity, immune response and the intestinal barrier of broiler chickens. In total, 1200 1-d-old broilers were randomly assigned to five dietary treatments, each with six replicate pens of forty birds for 63 d as follows: (a) basal diet (control), supplemented with (b) 1 × 109 colony-forming units (cfu)/kg Ba, (c) 300 mg/kg Enz, (d) 1 × 109 cfu/kg Ba and 300 mg/kg Enz and (e) 250 mg/kg enramycin (ER). Ba, Enz and BE, similar to ER, decreased the feed conversion rate, maintained intestinal integrity with a higher villus height:crypt depth ratio and increased the numbers of goblet cells. The BE group exhibited higher expression of claudin-1 and mucin 2 than the other four groups. BE supplementation significantly increased the α-diversity and β-diversity of the intestinal microbiota and markedly enhanced lipase activity in the duodenal mucosa. Serum endotoxin was significantly decreased in the BE group. Compared with those in the control group, increased superoxide dismutase and glutathione peroxidase activities were observed in the jejunal mucosa of the Ba and BE groups, respectively. In conclusion, the results suggested that dietary treatment with Ba, Enz or BE has beneficial effects on growth performance and anti-oxidative capacity, and BE had better effects than Ba or Enz alone on digestive enzyme activity and the intestinal microbiota. Ba or Enz could be used as an alternative to antibiotics for broiler chickens.

The intake of antinutritional factors produce impairment on the intestinal digestive function, impeding the efficient use of nutrients. Probiotics could be useful in poultry breeding to prevent negative effects of antinutritional factors, like the dietary lectins soybean agglutinin (SBA) and wheat germ agglutinin (WGA). Therefore, this investigation aimed to verify that SBA and wheat, which contains WGA, exert harmful effects on the intestinal mucosa and the digestive system of young poultry, and determine if the administration of probiotics able to capture lectins could counteract their effects. The trials performed demonstrated that a mixture of Bifidobacterium infantis CRL 1395, Enterococcus faecium LET 301, Lactobacillus salivarius LET 201, L. reuteri LET 210, and Propionibacterium acidipropionici LET 103, strains with ex vivo ability to interfere with the interaction of lectins and epithelial cells, has no negative effect on young chickens health. Middle levels of SBA, as well as wheat as a source of WGA, resulted in lower activities of intestinal and brush border enzymes and alterations in the integrity and morphological parameters of the chicks jejunal mucosa. The bacteria blend increased the activity of several digestive enzymes and the intestinal maturation marker alkaline phosphatase in birds fed with a conventional diet. Besides, it partially countered the deleterious effects of increased content of SBA, as well as the negative effect of a dietary source of WGA, on digestive enzymes activity and intestinal mucosa integrity. The results highlight the capability of multifunctional bacterial mixtures to protect the digestive system of avian against residual dietary lectins.

An experiment was conducted to investigate the supplementation of two commercially available multistrain probiotics as an alternative to antibiotics on growth performance, intestinal morphology, lipid oxidation and ileal microflora in broiler chickens. A total of 280-day-old ROSS 308 mixed-sex broiler chickens with an average initial body weight of 42 ± 0.5 g were randomly divided into four treatments with five replicate cages of 14 birds each cage in a completely randomized design and fed with the following diets for 42 day: (a) control (CON) (antibiotic-free diet), (b) antibiotic (ANT) (CON + Avilamycin 150 g/ton feed), (c) probiotic A (CON + Protexin 150 g/ton feed) and (d) probiotic B (CON + Bio-Poul 200 g/ton feed). The results showed the broilers fed the ANT diet had greater average daily gain than broilers fed the CON diet during day 1-14 (p < 0.05). At day 42, two birds were randomly selected per replicate for evaluation intestinal morphology, lipid oxidation and ileal microflora. birds fed diet supplemented with probiotic A and probiotic B increased villus height and goblet cells numbers in the jejunum and villus height to crypt depth ratio and villus height in the ileum as compared to birds fed CON diet (p < 0.05). The malondialdehyde value was reduced (p < 0.05) in the ANT, probiotic B and probiotic A groups compared with the CON group. The Lactobacillus population was increased and Clostridium spp. population decreased in the ileum of broilers fed diets containing the probiotic B and probiotic A compared with those fed CON diet (p < 0.05). The results from this study indicate that the probiotic A (Protexin ) and probiotic B (Bio-Poul ) used in this trial may serve as alternatives to ANT.

This study investigated the effects of dietary Paenibacillus xylanexedens ysm1 supplementation on growth performance, intestinal morphology, immune response, and cecal microbiota of broiler chickens challenged with Escherichia coli K88. A total of 320 one-day-old male broiler chicks were randomly allocated to 4 treatments (8 floor pens, 10 birds/pen) including 1) negative control (NC) birds fed a basal diet and not challenged with E. coli K88; 2) positive control (PC) birds fed a basal diet and challenged with of E. coli K88; 3) P. xylanexedens ysm1 treatment (PRO) birds fed a basal diet supplemented with 1 × 10P. xylanexedens ysm1 cfu/kg feed and challenged with E. coli K88; and 4) antibiotic treatment (ANT) birds fed a basal diet supplemented with 20 mg of colistin sulphate/kg of feed and challenged with E. coli K88. The E. coli challenge decreased (P < 0.05) BWG in PC birds compared with the ANT birds on days 21 and 28. The FCR was higher (P < 0.01) in PC birds compared with the NC, PRO, and ANT birds on days 14, 21, and 28. Compared with the NC, PRO, and ANT birds on day 28, PC birds had shorter villi and higher number of goblet cells in both jejunum and ileum (P < 0.001). Irrespective of the dietary treatments, the E. coli challenge reduced the number of PCNA-positive cells in both the jejunum and ileum on day 28. Paenibacillus xylanexedens ysm1 treatment resulted in higher concentration of mucosal sIgA in the jejunum as compared to the other treatment groups on days 14 and 28. The numbers of cecal E. coli were reduced (P = 0.017) in broilers treated with P. xylanexedens ysm1 or antibiotic in comparison with the PC group on day 28. In conclusion, the present study demonstrated that dietary supplementation of this new probiotic bacteria P. xylanexedens ysm1 improved broiler performance by modulating intestinal morphology, enhancing immune response, and reducing the number of E. coli in the cecum.

Epithelial damage and loss of barrier integrity occur following intestinal infections in humans and animals. Gut health was evaluated by electron microscopy in an avian model that exposed birds to subclinical necrotic enteritis (NE) and fed them a diet supplemented with the probiotic Bacillus amyloliquefaciens strain H57 (H57). Scanning electron microscopy of ileal mucosa revealed significant villus damage, including focal erosions of epithelial cells and villous atrophy, while transmission electron microscopy demonstrated severe enterocyte damage and loss of cellular integrity in NE-exposed birds. In particular, mitochondria were morphologically altered, appearing irregular in shape or swollen, and containing electron-lucent regions of matrix and damaged cristae. Apical junctional complexes between adjacent enterocytes were significantly shorter, and the adherens junction was saccular, suggesting loss of epithelial integrity in NE birds. Segmented filamentous bacteria attached to villi, which play an important role in intestinal immunity, were more numerous in birds exposed to NE. The results suggest that mitochondrial damage may be an important initiator of NE pathogenesis, while H57 maintains epithelium and improves the integrity of intestinal mucosa. Potential actions of H57 are discussed that further define the mechanisms responsible for probiotic bacteria's role in maintaining gut health.

The topic about the interactions between host and intestinal microbiota has already caught the attention of many scholars. However, there is still a lack of systematic reports on the relationship between the intestinal flora and intestinal physiology of birds. Thus, this study was designed to investigate it. Antibiotic-treated specific pathogen-free (SPF) bird were used to construct an intestinal bacteria-free bird (IBF) model, and then, the differences in intestinal absorption, barrier, immune, antioxidant and metabolic functions between IBF and bacteria-bearing birds were studied. To gain further insight, the whole intestinal flora of bacteria-bearing birds was transplanted into the intestines of IBF birds to study the remodeling effect of fecal microbiota transplantation (FMT) on the intestinal physiology of IBF birds. The results showed that compared with bacteria-bearing birds, IBF birds had a lighter body weight and weaker intestinal absorption, antioxidant, barrier, immune and metabolic functions. Interestingly, FMT contributed to reshaping the abovementioned physiological functions of the intestines of IBF birds. In conclusion, the intestinal flora plays an important role in regulating the physiological functions of the intestine.