The cost of parasitism: Metabolic aspects of the northern fowl mite-hen interaction

The northern fowl mite, Ornithonyssus sylviarum, is the main ectoparasite on egg-laying hens. Pesticide restrictions and housing changes are impacting available control options. One possible new target is breeding for mite-resistance. We tested the impact of both mite infestation and resistance on hen basal metabolic rates and egg production factors. Two distinct haplotypes linked to the major histocompatibility complex in white leghorn chickens were previously identified as either mite-resistant or mite-susceptible. Basal metabolic rates and related aspects such as skin inflammation of both haplotypes were tested before, during, and after a mite infestation. Weekly mite scores and economic parameters were recorded. Using metabolic and economic data we will determine which is more metabolically costly; an ectoparasite infestation or an immune response.