Associations among antimicrobial use, calf management practices, and antimicrobial resistance in Escherichia coli from a pooled fecal sample in calves on Canadian dairy farms: A cross-sectional study

• Published in: Journal of dairy science 2024-07, Vol.107 (7), p.4961-4972
• Main Authors: Uyama, T., Kelton, D.F., Morrison, E.I., de Jong, E., McCubbin, K.D., Barkema, H.W., Dufour, S., Fonseca, M., McClure, J.T., Sanchez, J., Heider, L.C., Renaud, D.L.
• Format: Article
• Language: English
• Subjects: ampicillin; antibiotic; antibiotic resistance; azithromycin; calves; cefoxitin; ceftriaxone; chloramphenicol; ciprofloxacin; colostrum; cross-sectional studies; dairy science; Escherichia coli; farms; feces; gentamicin; hay; heifers; herds; litter; multiple drug resistance; nalidixic acid; passive immunity; phenotype; regression analysis; sawdust; straw; streptomycin; sulfisoxazole; tetracycline; treatments
• ISSN: 0022-0302; 1525-3198; 1525-3198
• DOI: 10.3168/jds.2023-24262

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The objective of this cross-sectional study was to determine associations between calf management practices, the number of antimicrobial treatments, and antimicrobial resistance in preweaning heifers on Canadian dairy farms. A composite of 5 fecal samples from preweaning calves was collected from 142 dairy farms in 5 provinces and analyzed for phenotypic antimicrobial susceptibility with the microbroth dilution method. Questionnaires were used to capture herd characteristics and calf management practices used on the farm. Calf treatment records were collected during the farm visits. Escherichia coli was isolated from all 142 fecal samples with the highest resistance to tetracycline (41%), followed by sulfisoxazole (36%), streptomycin (32%), chloramphenicol (28%), ampicillin (16%), trimethoprim-sulfamethoxazole (15%), ceftriaxone (4.2%), cefoxitin (2.8%), amoxicillin-clavulanic acid (2.1%), ciprofloxacin (2.1%), nalidixic acid (2.1%), azithromycin (1.4%), and gentamicin (1.4%). Multidrug resistance was observed in 37% of E. coli isolates. Three-quarters of farms used fresh colostrum as the most common type of colostrum fed to calves. Colostrum quality was checked on 49% of farms, but the transfer of passive immunity was only checked on 32% of farms in the last 12 mo. Almost 70% of farms used straw or hay or a combination as the bedding material for calves. Among the 142 farms, a complete set of calf records were collected from 71 farms. In a multivariable logistic regression model, farms with ≥1.99 to 32.57 antimicrobial treatments/calf-year were 3.2 times more likely to have multidrug resistant E. coli in calf feces compared farms with