Establishment of the model of broilers infected with E.coli O157:H7 by tracheal instillation
The purpose was to establish a broiler model infected by enterohemorrhagic Escherichia coli O157:H7.One hundred one-day-old Mahuang broilers were randomly divided into 6 groups:control group,group A(1×107 cfu/mL E.coli infection group),group B(1×108 cfu/mL E.coli infection group),group C(1×109 cfu/mL E.coli infection group),group D(1×1010 cfu/mL E.coli infection group)and group E(1×1011 cfu/mL E.coli infection group),with 3 replicates per group and 5 broilers per replicate.Feeding to 7 days of age,broilers in E.coli groups were infected with 0.5 mL E.coli by tracheal instillation,while those in the control group were given the same volume of phosphoric acid buffer(PBS).The body weight before the experiment and 7 days after E.coli infection and the feed intake were recorded,and the clinical changes were observed during the experiment.7 days after infection,blood sample was collected from the jugular vein to detect liver function.The organ index of liver and spleen were calculated.The bacteria carrying capacity and histopathology were observed in liver,spleen and colon.Compared with control group,feed to gain ratio,liver index and spleen index in E.coli broilers were significantly increased(P<0.05).E.coli was detected in liver and spleen,and the number of E.coli in colon increased significantly.Compared with control group,the content of ALT(alanine aminotransferase)and T-bilirubin(total bilirubin)in all E.coli groups were significantly enhanced(P<0.05),and AST(aspartate aminotransferase)content also increased and the TBA(total bile acid)decreased in group D and group E(P<0.05).The histopathological results showed that the broiler liver color in groups C,D and E was greenish brown with white necrotic spots,serous exudation and infiltration of red blood and inflammatory cells by microscopy.The spleen in group E showed obvious capillary hyalinosis and capillary congestion.Intestinal villi atrophy and intestinal wall thinning were observed in groups C,D and E,and capillary congestion was observed in groups D and E.Tracheal instillation can be used to establish a model of E.coli in chickens,which can cause obvious liver and colon damage.
enterohemorrhagic Escherichia colitracheal instillationbroileranimal model
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