The incidence of parthenogenesis in turkey eggs can be influenced by environmental and genetic factors.
Age of the hen and the laying season. The overall incidence of parthenogenesis is higher in young hens (Olsen, 1967). These hens have a higher incidence of parthenogenetic developmentin infertile eggs in the first year than they experience during the second year of production. The laying season itself does not significantly affect the occurrenceof parthenogenesis (Olsen, 1968).
Live viruses. An increased occurance of parthenogenesis was observed in eggs from Beltsville Small Whitre turkey hens exposed to New Castle Disease, Fowl Pox (Olsen and Buss, 1967), and Rous Sarcoma viruses (Olsen and Poole, 1962). Vaccination of turkey hens with killed viruses did not increase the occurance of parthenogenesis (Olsen, 1962).
Feed. Some additives combined with the feed to enhance reproductive efficiency, such as a yeast culture of Saccharomyces cerevisiae, have stimulated parthenogenetic development. The increased expression of parthenogenetic development resulting from the yeast culture was influenced by the hen's genotype (Savage et al., 1993).
Inactivated sperm. Use of irradiated sperm to inseminate hens is another example of enhancing the incidence of parthenogenesis (Sarvella, 1971). The sperm used in the study although inactivated by irradiation (i.e. unable to contribute genetic material) remained motile.
Preincubation storage temperature. Elevated pre-incubation egg storage temperature can increase the incidence of parthenogenesis (Schom et al., 1982).
Strain. There are genetic strain and line differences in the occurance of parthenogenesis. Twenty-four lines and crosses of chickens were investigated for their predisposition to develop parthenogenetically. Olsen (1966) found that some genetic strains had significantly higher incidences of parthenogenetic development.
Genetic selection for parthenogenesis. The incidence of parthenogenesis could be increased by genetic selection. Olsen (1965) successfully selected Beltsville Small White Turkeys over several generations for an increased incidence of parthenogenesis. Associated with the response to selection was a shift from unorganized membranes to a more highly organized type of membrane development.
Selection for semen volume. A significant difference in parthenogenesis was observed between two lines of Medium White Turkey selected for divergent ejaculate volumes (Savage and Harper,1985).
Proceed to Materials and Methods Used