Dr. Chintu RavishankarSARITHA BABY2024-04-022024-04-022023-03-25https://krishikosh.egranth.ac.in/handle/1/5810208033Neonatal calf diarrhea (NCD) is a major threat to cattle farmersworldwide. It causes huge financial losses mainly due to morbidity andmortality of the calves. The etiology of NCD is complex disease in which both infectious agents and non infectious factors are involved. A comprehensiveanalysis was carried out to detect the major bacterial and viral agentsresponsible for NCD in Kerala and also to assess non-infectious factors thatcontribute to the condition. A total of 120 diarrhoeic faecal samples collected from different cattle farms in Thrissur and Wayanad districts of Kerala duringthe period from October 2019 to September 2022 were used for the study.Each farm has its own management practices that were found to influence the onset of diarrhoea. In the study it was observed that unhygienic conditions, overcrowding and changes in nutrition were the major predisposing factors for NCD. The incidence of diarrhoea was higher in farms housing large number of animals. Calves below one month of age were affected the most and the maximum number of diarrhoeic calves (26 per cent) was found in the 22-30 days age group. Among the infectious agents, E. coli, Salmonella, rotavirus and coronavirus were focused in the current investigation. The isolated bacteria were characterized by biochemical testing and E. coli was found to be the main infectious agent associated with the condition with a prevalence of 84.17 per cent. From the 120 samples, a total of 101 isolates of E. coli could be isolated. None of the samples were found to be positive for Salmonella. Antibiotic sensitivity testing revealed that the all E. coli. isolates were resistant to Penicillin G, Cefotaxime/Clavulanic acid and Cefpodoxime. The percentage of isolates resistant to Amoxicillin/sulbactam and Enrofloxacin, Ciprofloxacin, Co-Trimoxazole and Tetracycline, Gentamicin, and Nitrofuratonin were 92.08 per cent, 85.15 per cent, 80.2 per cent, 77.23 per cent, and 72.25 per cent respectively. Only 53.47 and 51.49 per cent of the isolates were resistant to chloramphenicol and streptomycin, respectively. When the E. coli isolates were subjected to phylogrouping using a quadruplex PCR, it was observed that B1 was the most prevalent group in this study with 28 isolates. Group A, D, C, E, F and clade I were also detected but with a lower prevalence. The fimbrial genes are responsible for virulence of E. coli and played a role in causing diarrhoea. The presence of fimbrial genes F5, F41 and F17 was also tested employing PCR. Of the isolates tested ten were detected as positive for F17 with a positivity of 16.13 per cent. Fimbrial genes F5 and F41 were not detected in any of the isolates. Reverse transcriptase polymerase chain reaction (RT-PCR) was employed for the detection of the viral agents. For rotavirus and coronavirus, VP6 gene and N gene were targeted respectively. Out of the 120 samples, 14 (11. 67 per cent) were found to be positive for rotavirus. The diarrhoeic faeces of calves infected with rotavirus were gray or creamy white and watery and all the affected calves were above one week of age. Coronavirus could not be detected in any of the samples. The results of the study indicate that diarrhoea in calves in Kerala was caused by both bacterial and viral agents. Varying degrees of antibiotic resistance were also detected against the common antibiotics. Good care of the new born calves and hygienic practices in farms will go a long way in control of the conditionEnglishThesis