الفهرس 
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Abstract
Neonatal calf diarrhea (NCD) is a major disease worldwide leading to dehydration and various body fluid changes also it affects the immunological state of calves. Therefore, this study is carried out to:1- Isolate, detect and serotype E.coli and Salmonella isolates with special reference to E.coli K99. 2- Detect the incidence of members of family Enterobacteriaceae in calf diarrhea. 3- Detect the gene coding enterohemolysin (hly) of E. coli isolated from diarrheic calves. 4- Measure non specific immune response parameters as lysozyme, free radicals (NO & MDA) and TAC. 5- Correlate between the parameters and types of microbial infection. 6- Use the electrophoretic technique as a useful tool for diagnosis of neonatal calf diarrhea through the comparison between the general protein patterns of serum samples of some healthy and diseased calves using polyacrylamide gel electrophoretic technique. In this study a total of 132 faecal swabs and blood samples (124 and 8 of diarrheic and healthy calves, respectively) were collected from governmental and private farms in different localities in El-Bohira governorate, on the 5th day after birth and at age 1 month. The serum was obtained from whole blood, non-homogenised. Bacteriological investigation revealed that the most common bacterial isolate was E.coli (92.74%) followed by Proteus mirabilis (31.45%), Proteus vulgaris (22.6%), Pseudomonas aeruginosa (11.3%), Shigella spp.(5.65%),Enterobacter aerogenes (5.65%), Enterobacter cloacae(4.03%), Citrobacter fruendii (2.42%), Citrobacter diversus (0.8%), Salmonella Pietersburg (0.8%) and Klebsiella pneumonia (0.8%). Also a total of 66 cases of mixed E. coli isolates with other bacteria were recorded (53.2%). Serotyping of E. coli isolates revealed O146, O1, O18 and O158 with an incidence of 42.9%, 28.6%, 14.3% and 14.3%, respectively. Only E. coli O146 was positive for K99. In the present study hly gene was detected in 1 out of 5 E. coli isolates which selected randomly with an incidence of 20% using PCR technique. Also serotyping of Salmonella isolate revealed Salmonella Pietersburg (O3,15;269; 1,7). Regarding to non specific immune response, NO concentration increased significantly (P<0.0008) in diseased vs normal control calves, also lysozyme increased significantly over the control (P<0.001), by increased secretion of killing molecules due to bacterial infections, MDA secreted as a result of cell lipid peroxidation, on the other hand TAC concentrations in sera of diseased calves were significantly lower than that in sera of normal control. from our result we detected that in case of severe bacterial infection the concentration of lysozyme, MDA and NO parameters significantly increased than other cases of bacterial infection, also TAC decreased in severe cases of bacterial infection than other cases of bacterial infection. There is a negative weak correlation in lysozyme ( -0.16) between mean of infected calves vs its control. Meanwhile, there is a positive weak correlation between mean of NO (0.21), MDA (0.17), and TAO (0.196) in sera of infected calves vs. their control. By measuring of serum total protein and fractionation of serum proteins by means of zone electrophoresis, serum total protein increased in diarrheic calves than normal healthy cases, also albumin level increased in diarrheic calves than healthy control cases but gamma globulin decreased in severe cases of diarrhea. Alpha globulin slightly increased in severely diarrheic calves. Nearly there is no significant difference in level of betta globulin between diseased and healthy calves. Finally A/G ratio increased in diarrheic calves than healthy control cases.