Antimicrobial usage in 60 Swedish farrow-to-finish pig herds

- Treatment incidences vary considerably between Swedish pig herds.
- Most treatments were applied to suckling piglets.
- Individual treatment, mainly consisting of injectables, was most common.
- Injectable benzylpenicillin was the most commonly applied antimicrobial substance.
- Oral formulations of tylosin was the most commonly applied treatment for weaners.

The aim of this study was to quantify antimicrobial consumption in Swedish farrow-to-finish pig herds. Sixty herds with 100 sows or more producing more than 500 fatteners per year participated in a study where data on antimicrobial consumption over a period of one year were collected. Data on antimicrobial use were collected by substance, administration route and per age category. Antimicrobial use was measured as defined daily doses and expressed as treatment incidence (TI) per 1000 pig-days at risk. The TIs for growing pigs varied between herds, from 1.6 to 116.0 with a median of 14.3. The highest TI was recorded for suckling piglets with a median of 54.7 (range; 1.6-367.9), while the median TIs for weaners, fatteners and adults were 6.2, 2.8 and 8.4, respectively (range; 0.0-260.5; 0.0-64.9; 0.0-45.0, respectively). The within herd TIs for the different age categories were not correlated. Individual treatment, mainly consisting of injectables, was the most common form of application except for weaners for which a majority (54.8%) of the treatments were group treatments. Benzylpenicillin was the most commonly applied substance except for weaners for which oral formulations of tylosin were most common. For fatteners, group treatments constituted 8.4% of the total TI. Group treatments with oral colistin were applied to suckling piglets in five herds. Group treatments were not applied to adult pigs. The TI for weaners was significantly lower for specific pathogen-free herds. The results show that the overall antimicrobial use in Swedish farrow-to-finish pig herds varied to a great extent, and the between-herd variation indicates that there is room for improvement of pig health. Targeting suckling piglets may be most beneficial, but further studies are required to identify specific focus areas which may reduce the need for antimicrobials in this particular age group.