Abstract: [Objective]To determine the main pathogens causing diarrhea in calves and their antibiotic resistance in a large-scale dairy farm in Shihezi area, and to propose reasonable measures against calf diarrhea, providing a reference for the prevention and treatment of calf diarrhea in the farm. [Methods]This study conducted on-site epidemiological examinations, aseptically collected 15 diarrheal samples from calves, and performed pathogen isolation and purification. The pathogens causing calf diarrhea were identified through biochemical tests and molecular biology identification. Antibiotic sensitivity tests were conducted to determine the drug resistance of the pathogens. [Results]Through biochemical tests and molecular biology identification, Escherichia coli was isolated from 12 out of 15 calf diarrhea samples. The antibiotic sensitivity test results showed that the highest resistance rate of 13 E. coli strains was to streptomycin at 46.15% (6/13), followed by penicillin and ampicillin at 38.46% (5/13), with most sensitive strains being moderately or weakly sensitive; the sensitivity to tetracycline was 76.92% (10/13), and the highest sensitivity among the 13 strains was to ceftiofur and vancomycin at 84.62% (11/13), with most strains being multidrug-resistant. [Conclusion]This study provides a reference for the diagnosis and treatment of calf diarrhea in the farm by conducting pathogen isolation and identification, and antibiotic sensitivity tests on diarrheal calves.

Key words: calves diarrhea, Colibacillus, separation identification, drug resistance