The Tremendous Turkey by Dr. Karl Nestor
Parthenogenesis in Turkeys
Karl E. Nestor
Turkeys reproduce by natural mating or commercially are mated using artificial insemination. Is there another way in which turkeys can reproduce? Lower animals can sometimes reproduce by a process termed parthenogenesis in which unfertilized eggs develop. Parthenogenesis does not usually occur in higher animals but has been shown to occur in chickens and turkeys. Parthenogenetic development in chickens ceases long before the embryo develops to full term, therefore few chicks have been obtained by parthenogenetic development. Patricia Sarvella obtained one parthenogen chicken from a chicken hen that was not mated.
The same is not true for the turkey. Dr. M. W. Olsen working for the United States Department of Agriculture extensively studied the development of parthenogenesis in turkeys. He worked with a small variety of turkeys called Beltsville Small Whites. He found that the onset of parthenogenetic development in turkeys takes place three or four hours prior to ovulation or soon after ovulation of the ovarian follicle from the ovary. In Dr. Olsen’s early studies, the parthenogenetic development in eggs from nonmated hens would only proceed though the development of membranes and early blood formation by the embryo. He bred a strain of Beltsville Small Whites for a higher incidence of parthenogenesis in unfertilized eggs. As selection continued, the incidence of the condition increased and parthenogenic development proceeded to more advanced stages until an embryo that developed parthenogenetically from an unfertilized egg. The first poult that hatched by this method was moved, for safe keeping, from the research farm to Dr. Olsen’s basement. Unfortunately, his dog killed the turkey.
Dr. Olsen’s continued selection for increased incidence of parthenogenesis resulted in almost half of unfertilized eggs showing some development and some 8% of the embryos (200) hatched in the final year of selection, all were males. All of the parthenogenetic males were indistinquishable from males produced by natural or artificial mating and were capable of natural mating or producing semen for artificial inseminations. Research has shown turkey parthenotes start as haploids, they then become diploid due to inhibition of cell division or cell fusion. In birds females are the heterogametic sex (ZW) and males are the homogametic sex (ZZ), this is the opposite of mammals. WW parthenotes would not develop as this condition is not viable.
Several factors affect the frequency of parthenogenesis in chickens or turkeys. Vaccination with live virus vaccines such as Newcastle disease, fowl pox, and Rous sarcoma viruses increases the incidence of parthenogenesis. In general, parthenogenesis develops more from younger hens than older hens. Hormonal factors may be involved because housing females in sight or sound of males increases the incidence.
In summary, normal male turkeys can be hatched from unfertilized eggs by parthenogenesis. The incidence of the condition can be greatly increased by selection and can be increased by vaccinating the birds with live virus vaccines or having the nonmated females housed in sight of males.