Effects Of Pathogenic E.coli On Blood Biochemical Indexes?Antioxidant Capacity And Intestinal Morphology Of Newborn Calves

The purpose of this study was to investigate the effects of pathogenic E.coli O1 on blood biochemical parameters,antioxidant capacity,immune function and intestinal health in newborn calves.The results of this study provide a theoretical basis for the subsequent control and treatment of diarrhea caused by pathogenic E.coli O1 in calves.The experiment was designed by random group,64 healthy newborn Holstein Calves weighing 40?43 kg were selected and randomly divided into 2 groups,that is,the natural control group(NC)received the same dose of normal saline and the experimental group(EC)with the infusion of pathogenic E.coli O1(2.50 × 1011 CFU/mL,100 mL/head).Each group of 32 calves,the trial period is 30 days.At 12 h,24 h,36 h,48 h,72 h,5 d,10 d and one month,blood samples were collected from jugular vein of each group of calves,and supernatant was taken after centrifugation to determine serum biochemical indicators,antioxidant and immune indicators.Calves were selected for slaughter in each group at 24 h,72 h and 10 d.The test results are as follows:(1)The pathogenic E.coli O1 had some negative effects on the blood glucose and lipid metabolism of the calves,and the serum levels of ALT and AST of the test group significantly increased(P<0.05),which caused some damage to the kidney function and liver of the calves.(2)The pathogenic E.coli O1 significantly reduced the contents of SOD,GSH-Px and CAT in calf serum(P<0.05),and significantly reduced the content of SOD in calf serum at 48 h(P<0.01).This indicates that the antioxidant system of calves has been damaged to a certain extent.(3)At 10 d,compared with the control group,the quantity of E.coli in the rectum of calves in the test group was significantly increased(P<0.05);The content of lactic acid bacteria was significantly reduced(P<0.05).At 24 h in the duodenum and jejunum,the recess depth of the test group was significantly increased(P<0.05),but the V/C value was significantly decreased(P<0.05).At 72 h,the pathogenic E.coli O1 had the most serious effect on the ileal mucosal structure,and the ileal villi height and V/C value were significantly reduced(P<0.01).(4)The pathogenic E.coli O1 caused increased the contents of IL-6 and TNF-? in serum of calves,decreased the contents of IL-10 and IFN-? in serum,and there was a significant difference in the contents of inflammatory factors between the two groups between 24 h and 48 h(P<0.05).The content of 5-HT in the experimental group was significantly higher than that in the control group(P<0.05).