Laying hen production and welfare in a cage-free setting is impacted by the northern fowl mite

The northern fowl mite (Ornithonyssus sylviarum) is a common blood-feeding ectoparasite of poultry that can cause decreased egg production and reduced hen welfare. The blood-feeding behavior of the northern fowl mite (NFM) elicits an immune response in hens that leads to decreased egg production, anemia, irritation to flocks and personnel, profit loss, and death to hens in extreme cases. As the egg industry moves toward extensive housing systems, it is important to consider management implications of this switch, such as the impact of NFM infestations. In the present study, hens were infested with NFM in two trials. Production and welfare parameters were monitored throughout the duration of the trials, beginning at 18 wk of flock age, and ending at 47 and 49 wk of age for Trials 1 and 2, respectively. A cannibalism issue in Trial 1 resulted in a severe loss of hens by the end of the trial and a low overall NFM infestation, while Trial 2 had consistent NFM infestation levels. In Trial 1, NFM negatively affected hen-day percentage, body weight, and feather coverage of some body regions. In Trial 2, the NFM infestation negatively affected hen-day percentage, mortality, body weight, shell thickness, and feather coverage of some body regions.