Influence of northern fowl mite populations of parent chickens on their F1 progeny.

Roosters and hens that had carried either light (less than 100 mites/chicken) or heavy (greater than or equal to 10,000 mites/chicken) populations of northern fowl mites (NFM), Ornithonyssus sylviarum (Canestrini and Fanzago), for five consecutive months were mated to determine if their F1 progeny would carry similar population levels of NFM. The realized heritability estimates for the F1 progeny were .18 at 2 weeks, .40 at 4 weeks, .39 at 6 weeks, and .18 at 8 weeks postinfestation. Genetic selection either for or against NFM cannot be accomplished in one generation but steady progress from selection in either direction should be possible.