Adapting ectoparasite control to welfare-driven changes in poultry production systems

A profound challenge for animal agriculture is adapting to animal welfare concerns. Public opinion and legislators are pressuring poultry producers to switch from conventional “battery” cages to “furnished” cages or cage-free housing. Simultaneously, commonly used pesticides are being banned or disallowed. Pesticide restrictions and housing changes dramatically impact ectoparasite control options.

The northern fowl mite (NFM) is a key ectoparasite of U.S. poultry. NFM limit egg production, cause irritation to hens, and result in significant blood loss. Management of poultry ectoparasites has involved two main tactics: prevention (biosecurity) and pesticide use. In conventional cages, high-pressure pesticide sprays from below wet the vent feathers, where mites live. Chickens on solid floors, or in furnished cages, cannot be sprayed this way due to physical barriers. Typical pesticides also are prohibited for organic egg production.

Dustbathing is a natural behavior performed by birds in fine substrate to improve feather condition, and is being encouraged in newer production systems for welfare reasons. Diatomaceous earth (DE) is an environmentally-friendly, organic approved insecticide that can be mixed with sand or other materials in dustboxes. It suppresses mites, but does not completely exclude them, potentially allowing natural development of mite immunity. We are testing whether hens with access to DE-filled dustboxes before NFM are introduced (prophylactic use) will keep mites below economically damaging thresholds. Dustboxes were removed 6 and 10 weeks after mite introduction to test for protective hen immunity resulting from exposure to low mite numbers over time. Preliminary results show mite levels below suggested economic injury thresholds when DE-filled dustboxes are present. However, mite suppression is not sustained after boxes are removed.