The study aims to investigate the effects of adding different proportions of Codonopsis radix compound crude extracts to the rabbit diet on growth performance,immune status,intesti-nal enzyme activity,structure,and microbial composition.A total of 96 5-week-old New Zealand White rabbits were randomly divided into 4 groups,with 6 replicates per group.The control group(BC)was fed a basal diet,while the experimental groups(CM-H and CM-L)were fed a basal diet supplemented with 1 000 mg/kg and 500 mg/kg of Codonopsis radix compound crude extracts,re-spectively.The antibiotic group(CK)was fed a basal diet supplemented with 300 mg/kg of keto-tifen.The experimental period was 42 days.Blood samples were collected at days 21 and 42,and se-rum biochemical and immune markers were determined.Intestinal segments and contents were col-lected at day 42 for analysis of intestinal health.The results showed that compared with the BC group,the average daily gain,feed-to-gain ratio,and diarrhea rate were significantly higher(P＜0.05)in the CM-H and CM-L groups.The total cholesterol(Tchol)content in the serum was sig-nificantly lower in the CM-H group at day 21 and the CM-L group at day 42(P＜0.05).The high-density lipoprotein(HDL)was significantly higher in the CM-H and CM-L groups than in the CK group at day 42(P＜0.05),and the total protein(TP)in the serum was significantly higher in the CM-H and CM-L groups than in the BC group(P＜0.05).The IgG and IgM levels in the serum were significantly higher in the CM-H and CM-L groups than in the BC group(P＜0.05).In the CM-H and CM-L groups,the content of acetic acid in the colon was significantly higher than that in the BC group(P＜0.05).The content of propionic acid in the colon of the CM-L group was also significantly higher than that in the BC group(P＜0.05).The content of α-amylase in the duode-num,the content of trypsin in the duodenum,the pancreas,and the ileum of the CM-H group were significantly higher than those in the BC group(P＜0.05),and the content of trypsin in the duode-num of the CM-H group was significantly higher than those in the BC group and the CM-L group(P＜0.05).Compared with the BC group,the content of GPX1 in the ileum and jejunum of the CM-L group and the ileum of the CM-H group was significantly increased(P＜0.05),and the length of the villi in the duodenum of the CM-H group was significantly increased(P＜0.05).Compared with the BC group,the expression level of ZO-1 in the ileum of the CM-H group was significantly upregulated(P＜0.05),and the expression level of Claudin in the jejunum of the CM-H group and the CM-L group was significantly higher than that in the CK group(P＜0.05).The high-throughput sequencing results showed that the Sob index was significantly higher in the CM-L group compared to the BC group(P＜0.05).At the phylum level,the Firmicutes and Bacteroid-ota phyla were the main phyla.At the genus level,Akkermansia and Ruminococcus were the main genera.The relative abundance of Papillibacter and Eubacterium_ruminantium_group in the CM-L group was significantly higher than that in the CK group(P＜0.05).In summary,adding a Codonopsis radix compound crude extract to the diet can improve the growth performance,immu-nity,antioxidant capacity,integrity of intestinal mucosal structure,enzyme activity in the intestine,and increase the diversity of microorganisms in the blind intestine when the diet is supplemented with 500 mg/kg of Codonopsis radix compound crude extract.

The study aims to investigate the effects of adding different proportions of Codonopsis radix compound crude extracts to the rabbit diet on growth performance,immune status,intesti-nal enzyme activity,structure,and microbial composition.A total of 96 5-week-old New Zealand White rabbits were randomly divided into 4 groups,with 6 replicates per group.The control group(BC)was fed a basal diet,while the experimental groups(CM-H and CM-L)were fed a basal diet supplemented with 1 000 mg/kg and 500 mg/kg of Codonopsis radix compound crude extracts,re-spectively.The antibiotic group(CK)was fed a basal diet supplemented with 300 mg/kg of keto-tifen.The experimental period was 42 days.Blood samples were collected at days 21 and 42,and se-rum biochemical and immune markers were determined.Intestinal segments and contents were col-lected at day 42 for analysis of intestinal health.The results showed that compared with the BC group,the average daily gain,feed-to-gain ratio,and diarrhea rate were significantly higher(P＜0.05)in the CM-H and CM-L groups.The total cholesterol(Tchol)content in the serum was sig-nificantly lower in the CM-H group at day 21 and the CM-L group at day 42(P＜0.05).The high-density lipoprotein(HDL)was significantly higher in the CM-H and CM-L groups than in the CK group at day 42(P＜0.05),and the total protein(TP)in the serum was significantly higher in the CM-H and CM-L groups than in the BC group(P＜0.05).The IgG and IgM levels in the serum were significantly higher in the CM-H and CM-L groups than in the BC group(P＜0.05).In the CM-H and CM-L groups,the content of acetic acid in the colon was significantly higher than that in the BC group(P＜0.05).The content of propionic acid in the colon of the CM-L group was also significantly higher than that in the BC group(P＜0.05).The content of α-amylase in the duode-num,the content of trypsin in the duodenum,the pancreas,and the ileum of the CM-H group were significantly higher than those in the BC group(P＜0.05),and the content of trypsin in the duode-num of the CM-H group was significantly higher than those in the BC group and the CM-L group(P＜0.05).Compared with the BC group,the content of GPX1 in the ileum and jejunum of the CM-L group and the ileum of the CM-H group was significantly increased(P＜0.05),and the length of the villi in the duodenum of the CM-H group was significantly increased(P＜0.05).Compared with the BC group,the expression level of ZO-1 in the ileum of the CM-H group was significantly upregulated(P＜0.05),and the expression level of Claudin in the jejunum of the CM-H group and the CM-L group was significantly higher than that in the CK group(P＜0.05).The high-throughput sequencing results showed that the Sob index was significantly higher in the CM-L group compared to the BC group(P＜0.05).At the phylum level,the Firmicutes and Bacteroid-ota phyla were the main phyla.At the genus level,Akkermansia and Ruminococcus were the main genera.The relative abundance of Papillibacter and Eubacterium_ruminantium_group in the CM-L group was significantly higher than that in the CK group(P＜0.05).In summary,adding a Codonopsis radix compound crude extract to the diet can improve the growth performance,immu-nity,antioxidant capacity,integrity of intestinal mucosal structure,enzyme activity in the intestine,and increase the diversity of microorganisms in the blind intestine when the diet is supplemented with 500 mg/kg of Codonopsis radix compound crude extract.

An isolated virulence Riemerella anatipestifer strain passaged 200 times on TSB agar were used for the virulent to avirulent conversion. The effects of passage on biological properties of outer membrane proteins (OMPs) were investigated using the virulent and avirulent strains. Transmission electron microscopy demonstrated that the avirulent strain produced lower amounts of outer membrane vesicles and the outer membrane decreased, the cytoplasmic appearance jumbled. The OMPs of the virulent strain agglutinated only in RA serotype 2 antisera, whereas the OMPs of the avirulent strain agglutinated in antisera of RA 1, 2, 10 and 11. SDS-PAGE Analysis showed the OMPs profiles of both strains were similar but the immunoblotting profiles were different. The protective immunity against Riemerella anatipestifer infection was investigated by immunizations with OMPs in ducks. ELISA results showed that the OMPs induced the production of antibodies in immunized ducks, but the OMPs of virulence strain induced higher antibody titers than the attenuated strain (P < 0.05). RA2 group showed significantly higher survival rates (100%) than RA200 group (0%) after challenged with the homologous virulent strain. The ompA gene of both stains were also amplified by PCR, nucleotide homology was 99.9%. In conclusion, OMPs of virulent RA strain are suitable candidates for vaccine development. Biological properties of OMPs undergoes significant changes during serial passage and suggest that vigilance should be used when extrapolating data obtained from the study of high-passage strains.
Animals ; Bacterial Outer Membrane Proteins ; chemistry ; genetics ; immunology ; Ducks ; Flavobacteriaceae ; chemistry ; classification ; immunology ; Flavobacteriaceae Infections ; immunology ; microbiology ; veterinary ; Serotyping

In order to identify virulence factors of the pathogen, the outer membrane proteins of virulent and avirulent strains of Riemerella anatipestifer were compared by a proteome analysis. Three protein spots differentially expressed between the two strains were observed by 2-DE gels, and were further analyzed using in gel tryptic digestion and peptide mass fingerprinting. Three proteins were identified. W1 was Hsp20, W2 and W3 were transposon. Although the exact role of these proteins has not been characterized, the exclusive expression in virulent strain may indicate that they play an important role in the pathogenesis of Riemerella anatipestifer infection. Although only two virulence factors identified, it opens a path to the further analysis of virulence factors of Riemerella anatipestifer.