[Usage of antimicrobials on seven farms of beef producers in Switzerland].

INTRODUCTION: It was the objective of this study to evaluate morbidity, mortality, use of veterinary drugs and production output on seven representative Swiss beef fatteners, who bought on a regular basis batches of calves from traders (mean age and weight: 31 day, 75 kg) and practised an all in-all out system. From March 2015 until May 2016, 51 batches with a total of 1307 calves were included. The use of drugs during the first eight weeks following delivery of calves from the trader, casualty rate and carcass performance of 837 bulls. The administration of antimicrobials was calculated per calf as the number of days with effective therapeutic concentrations (daily doses per animal; DD/A). The average weight of the calves at arrival on the fattening unit was 75 kg and the age 31 days. The group size was between 13 to 47 calves (median 22, Q1 = 21, Q2 = 30). In 36 batches (70,6 %), a veterinary entry examination was performed which demonstrated that at admission 20 % of the calves suffered from a relevant disease. The median for the number of DD/A was 16 for the first 56 days on the farm (Q1 = 11, Q3 = 21); 68 % of these DD/A were attributed to metaphylactic medications after delivery. Thereafter, pneumonia (54 %), diarrhea (33 %) and otitis (10 %) were the most frequent indications for subsequent therapeutic interventions. Over all batches, a median of 71 % (Q1 = 47, Q3 = 85) of all DD/A were due to critically important antimicrobials (CIM) and drugs containing several antibiotics including a CIM. The losses due to death or euthanasia averaged 3,7 % of all calves. The median for daily weight gain for the total fattening period (median 354 days; Q1 = 328, Q3 = 379) accounted for 1325 g (Q1 = 1216, Q3 = 1425). The profound variation between the farms in respect to the results of drug use and production output reveals evidence for the strong impact of farm-specific factors (such as pen space per calf, barn climate, vaccination protocol, supervision). Concurrently, the remarkable differences between the results of different batches on one farm depict that there are further important risk factors which are beyond the control of the farmer (in particular season of the year, transport). It is concluded that a systematic minimization of risk factors as part of a continuous veterinary consultation is useful two improve herd health and to reduce the input of drugs in the production of beef.