Effects of dietary supplementation by modified palygorskite and essential oil/palygorskite complex on growth performance and intestinal flora composition of broilers with diarrhea.

With the development trend of the industry, it can be seen that the substitution of antibiotics and reduction of zinc oxiden is still the hot spot of the industry. Diarrhea and inflammation occur frequently during livestock and poultry production, which is difficult to control. This experiment aimed to explore the effects and mechanisms of dietary supplementation of modified palygorskite (Mpal) and essential oil/ palygorskite composite (EO-PGS) on disease resistance and intestinal inflammatory damage in diarrhea broiler. In this experiment, there were a total of 420 broilers of 10-day-old selected and divided into 7 groups (n = 60), which were the nondiarrhea group fed with basal diet (normal control, NC), the diarrhea group fed with basal diet (diarrhea control, DC), and the rest were the diarrhea test group (diarrhea), supplemented with 1 kg/t, 2 kg/t and 4 kg/t of essential oils/ palygorskite complex (EO-PGS 1kg/T, EO-PGS 2kg/T, EO-PGS 4kg/T) in the basal diet, respectively, and 2 kg/t, 4 kg/t modified palygorskite group (Mpal 2kg/T, Mpal 4kg/T) in the basal diets, respectively. The experiment lasted for 8 d. The results showed that compared to normal broilers, the diarrhea index of diarrhea broilers remained around 2.0 with persistent mild diarrhea during the test period. The duodenal epithelial cells were damaged and shed, goblet cells increased, inflammatory cells infiltrated, diffuse congestion and hemorrhage in lamina propria, the serum lipopolysaccharides (LPS) content, and malondialdehyde (MDA) content increased significantly (P < 0.05). The serum superoxide dismutase (SOD) activity and immunoglobulin-M (IgM) levels significantly decreased, while serum immunoglobulin-G (IgG) and complement 3 (C3) levels significantly increased (P < 0.05). The expression of inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and nuclear factor κB (NF-κB) in duodenal epithelial cells was significantly upregulated on d 5 (P < 0.05). The abundance of Bacteroides in the duodenum of diarrhea broilers was significantly decreased, while the abundance of Proteobacteria was significantly increased (P < 0.05). Feeding diets supplemented with EO-PSG and 4 kg/t Mpal increased the average weight of diarrhea broilers (P < 0.05), reduced diarrhea index, improved immunity by increasing serum IgG, IgM, C3 and complement 4 (C4) levels (P < 0.05), enhanced the activity of serum antioxidant enzyme glutathione peroxidase (GSH-PX) and SOD activity, reduced serum MDA content, serum LPS levels, and decreased the expression of proinflammatory factors in the duodenal epithelial cell on d 5 (P < 0.05), alleviated duodenal epithelial cell injury, hemorrhage, inflammation infiltration and intestinal injury of diarrhea broilers from d 5 to d 8. Meanwhile, supplemented with EO-PSG and Mpal in diets regulated the intestinal microbiota, significantly increased the abundance of Bacteroidetes and decreased the abundance of Proteobacteria at the phylum level (P < 0.05). Microbial richness and diversity of microbiota were significantly increased by feeding the diet supplemented with 2 kg/t EO-PGS. In the beta diversity of the intestinal flora of the diets supplemented with 4 kg/t Mpal and 2 kg/t EO-PGS, the microbial community composition could be relatively easily distinguished with NC and DC groups. As a result of LEfSe analysis, the diets supplemented with 2 kg/t EO-PGS f_Clostridiaceae and g_Coprococcus were enriched in the caecum of diarrhea broilers, and the diets supplemented with 4 kg/t Mpal o_Bacteroidales, f_Rikenllaceae and g_Peptococcus were enriched in caecum of diarrhea broilers, between normal and diarrhea broilers (P<0.05). In conclusion, dietary supplementation with EO-PGS and Mpal could improve disease resistance and alleviate intestinal inflammatory damage in diarrhea broilers, but the effect of 2 kg/t Mpal was not significant. It was recommended that 2 kg/t EO-PGS or 4 kg/t Mpal be added to the broilers' diet according to the degree of diarrhea, and continuous feeding for more than 5 d.