To Isolate and Identify Escherichia coli and Salmonella Species from Faecal Samples of Diarrhoeic Calves

Abstract

Calf diarrhoea is one of the most important diseases affecting neonatal calves and is a major cause of morbidity, mortality and economic losses in the dairy industry worldwide. Among the bacterial pathogens associated with neonatal calf diarrhoea, Escherichia coli and Salmonella spp. are considered the principal aetiological agents. The present study was undertaken to determine the occurrence of calf diarrhoea and to isolate and identify Escherichia coli and Salmonella spp. from diarrhoeic cattle calves. The study was conducted over a period of six months from November 2025 to April 2026 at the Veterinary Clinical Complex, Livestock Farm Complex Adhartal, organised dairy farms and unorganised dairy sectors of Jabalpur, Madhya Pradesh. A total of 100 cattle calves were screened for diarrhoea based on clinical examination, faecal consistency and frequency of defecation. Of the 100 calves, 32 were found positive for diarrhoea, indicating an overall occurrence of 32.00 per cent. Eighteen diarrhoeic calves were subsequently selected for therapeutic evaluation, and faecal samples collected from these calves were processed for bacteriological examination. Samples were enriched in selective enrichment broths and cultured on MacConkey agar, Eosin Methylene Blue (EMB) agar, Rappaport vasidalis agar and Xylose Lysine Deoxycholate (XLD) agar for the isolation of Escherichia coli and Salmonella spp. The suspected isolates were further characterised by colony morphology, Gram staining and standard biochemical tests, including catalase, oxidase, urease and IMViC reactions using the KB001 HiIMViC™ biochemical identification kit. Bacteriological analysis revealed that Escherichia coli was isolated from 9 (50.00%) of the 18 diarrhoeic calves, whereas Salmonella spp. were not detected in any of the faecal samples examined. The findings indicate that E. coli was the predominant bacterial isolate recovered from the examined diarrhoeic calves based on culture and biochemical identification during the study period, while Salmonella spp. did not contribute to the disease during the study period.