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).
or