Embryonic malpositions in broiler chickens and bobwhite quail

One of the factors contributing to failure of avian embryos to hatch is the positioning of the embryo at the end of incubation in such a manner that emergence from the egg is inhibited. Abnormal positions, or malpositions, may also be associated with other problems without directly affecting the ability of the chick to hatch. The effect of strain, breeder age, and gender of embryo on incidence of malpositions before hatching was determined in broiler embryos. The effect of strain, breeder age, pre-incubation egg storage, setting orientation, and turning during incubation on incidence of malpositions before hatching was determined in bobwhite quail embryos. Although there were variations among strains and between genders for incidence of malpositions, they were not statistically significant. Differences among settings and evaluators were as great as strain effects. No significant strain or breeder age effect on malposition incidence was found in quail. Long-term pre-incubation storage increased the incidence of quail embryos with head between the thighs, possibly related to delayed embryonic development. Setting quail eggs with the small end up resulted in 75% of the embryos with head in the small end of the egg. Eggs set normally but not turned had increased incidences of head in small end, beak away from air cell, and head over wing embryonic malpositions. Therefore, in these studies, the incidence of malpositions was affected by pre-incubation egg storage, egg orientation, and turning, whereas it was not affected by strain, embryo gender, and breeder age.