Antimicrobial drug use and risk factors associated with treatment incidence and mortality in Swiss veal calves reared under improved welfare conditions

• Published in: Preventive veterinary medicine 2016-04, Vol.126, p.121-130
• Main Authors: Lava, M., Schüpbach-Regula, G., Steiner, A., Meylan, M.
• Format: Article
• Language: English
• Subjects: Agriculture; Animal Welfare; Animals; Anti-Infective Agents - therapeutic use; Cattle; Cattle Diseases - drug therapy; Cattle Diseases - epidemiology; Cattle Diseases - mortality; Defined daily dose; Drug Utilization Review; Female; Group treatment; Incidence; Individual treatment; Male; Quarantine; Red Meat; Retrospective Studies; Risk Factors; Switzerland; Treatment intensity; Vaccination
• ISSN: 0167-5877; 1873-1716
• DOI: 10.1016/j.prevetmed.2016.02.002

•Overall mean treatment incidence in Swiss veal calves was 21 days/calf/year.•Health check and quarantine were associated with reduced treatment incidence.•Shared air space among groups was associated with increased treatment incidence.•Vaccination, beef breed, and small homogeneous groups reduced the mortality risk.•The principles of prudent use of antimicrobials were insufficiently applied. Ninety-one Swiss veal farms producing under a label with improved welfare standards were visited between August and December 2014 to investigate risk factors related to antimicrobial drug use and mortality. All herds consisted of own and purchased calves, with a median of 77.4% of purchased calves. The calves’ mean age was 29±15days at purchasing and the fattening period lasted at average 120±28 days. The mean carcass weight was 125±12kg. A mean of 58±33 calves were fattened per farm and year, and purchased calves were bought from a mean of 20±17 farms of origin. Antimicrobial drug treatment incidence was calculated with the defined daily dose methodology. The mean treatment incidence (TIADD) was 21±15 daily doses per calf and year. The mean mortality risk was 4.1%, calves died at a mean age of 94±50 days, and the main causes of death were bovine respiratory disease (BRD, 50%) and gastro-intestinal disease (33%). Two multivariable models were constructed, for antimicrobial drug treatment incidence (53 farms) and mortality (91 farms). No quarantine, shared air space for several groups of calves, and no clinical examination upon arrival at the farm were associated with increased antimicrobial treatment incidence. Maximum group size and weight differences >100kg within a group were associated with increased mortality risk, while vaccination and beef breed were associated with decreased mortality risk. The majority of antimicrobial treatments (84.6%) were given as group treatments with oral powder fed through an automatic milk feeding system. Combination products containing chlortetracycline with tylosin and sulfadimidine or with spiramycin were used for 54.9%, and amoxicillin for 43.7% of the oral group treatments. The main indication for individual treatment was BRD (73%). The mean age at the time of treatment was 51 days, corresponding to an estimated weight of 80–100kg. Individual treatments were mainly applied through injections (88.5%), and included administration of fluoroquinolones in 38.3%, penicillines (amoxicillin or benzylpenicillin) in 25.6%, macrolides in 13