Assessment of fluralaner as a treatment in controlling Dermanyssus gallinae infestation on commercial layer farms and the potential for resulting benefits of improved bird welfare and productivity

Abstract Background Poultry red mite (PRM) ( Dermanyssus gallinae ) infestations are a cause of anaemia, impaired productivity and stress-related behaviours linked to reduced hen welfare. A study investigated the potential health, welfare benefits following fluralaner treatment eliminate PRM from infested hens. Methods PRM-infested layer house was selected on free-range farm (5400 hens) an aviary (42,400 hens). Fluralaner (Exzolt ® ; 0.5 mg/kg body weight) administered twice, 7 days apart (Weeks 0 1), via drinking water. Mite populations were monitored by traps. Cameras recorded nighttime weekly, pre- post-treatment. On farm, daytime also weekly. For post-treatment corticosterone assessments, eggs randomly collected both farms, blood samples 50 Production parameters assessed using records. Results Throughout period, efficacy against > 99% farms. followed significant increases in proportion resting hens P < 0.0001; = 0.0175, respectively). Significant versus pre-treatment reductions observed head shaking (aviary, 0.0233) preening 0.0032; 0.0018) bouts 0.0108), vertical wing 0.0002), scratching 0.0335), gentle feather pecking 0.0001). there 0.0001), 0.0492) 0.0012). Relative standard production parameters, no differences detected but laying rate decline with increasing age less than expected increase egg weight greater expected. Post-treatment plasma suggestive stress factors addition infestation. Red cell counts haematocrit increased treatment. Conclusion eliminated challenge, leading improved based restoration anaemia-inducing effects feeding. Graphical