The effect of ambient temperature on turkey embryonic development at oviposition

Stage of embryonic development at oviposition was measured in turkey breeder hens maintained in relatively warm and cool environments. The premise was that variations in embryonic development at oviposition might account for the decreased hatchability associated with warm summer temperatures. No treatment effect was found, as judged by somite counts after 52 h of incubation. Variation in embryonic development was as great within a hen as between hens, indicating that causative factor(s) other than stage of development at oviposition is the reason for reduced hatch of fertile eggs during periods of relatively high environmental temperature.