Risk factors associated with Brachyspira hyodysenteriae PCR-positivity in East-European pig production units

The objective of the present study was to determine the risk factors for swine dysentery in East-European middle-to-large sized, farrow-to-finish units, with separate breeding and grower-finisher facilities. Samples of faeces from 10 breeding animals (3-10% of the female inventory) and 10 grower finisher pigs (80-140 days of age) were collected for polymerase chain reaction testing (PCR) for Brachyspira hyodysenteriae (B. hyo). Of 139 farrow-to-finish units, 51 (36.7%) were positive, 49 (35.3%) were negative, and 39 (28.1%) were inconclusive for B. hyo by PCR. In breeding subunits, twelve variables passed the screening criterion for risk factors (P < .2) for B. hyo PCR positivity. The odds of the breeding subunits being B. hyo PCR positive were 3.5 times greater when the grower-finisher subunit was positive and the fibre content of the diet was > 6%. Use of 'all-in-all-out' farrowing policy and having >60% multiparous sows each reduced the odds of being B. hyo PCR-positive by 4-fold. In grower-finisher subunits, fourteen variables passed the screening criterion for risk factors (P < .2) for B. hyo PCR positivity. B. hyo PCR-positive status of the breeding subunits and higher fibre content of the diet were the most influential variables, with the odds of the grower-finisher subunits being B. hyo PCR positive being almost 8 times greater when the breeding subunit was also B. hyo PCR positive. Grower-finisher B. hyo PCR positivity was also associated with the percentage of pigs housed on concrete slats, with the odds of being positive being 7.5-times higher for subunits where more that 70% of the animals were kept on concrete slats compared with all other floor types. There was a strong association between grower-finisher status and whether the animals were on outdoor lots, with the odds of being B. hyo PCR positive being substantially lower for pigs on outdoor lots compared with all other surfaces. IN CONCLUSION: All-in-all-out management in the breeding units, B. hyo negativity of adjacent grower-finisher units, high fibre content of the diet, and older parity structure in a sow herd may reduce the risk of swine dysentery. In grower-finisher units, slatted flooring is associated with a higher risk, while B. hyo negativity of the breeding units, the fibre content of the diet, and outdoor production are associated with lower risk of swine dysentery.