Biology
The porcine zona pellucida (PZP) antigens in contraceptive
vaccines such as SpayVac™ cause a treated female mammal to
produce antibodies that adhere to the surface of her own eggs and
prevent sperm from binding, thus blocking fertilization.
Field
Use
Because SpayVac™ is long lasting, it can be administered
whenever fieldwork is most efficiently conducted and when animals
can be captured safely and easily. To avoid treating animals repeatedly,
which would expose them to stress and potential injury, animals can
be marked with ear tags, collars, tattoos, and/or microchip tags.
In hunting areas, these marks enable hunters to discriminate between
treated and untreated animals.
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| Controlling
Wildlife Populations
Controlling overabundant populations of wildlife requires
more than just effective fertility control:
a large proportion of the population must be treated to result in a decline.
As a rule-of-thumb for deer populations, treating 80% of the reproductive females
is necessary. Research on deer populations at the Fire Island National Seashore,
New York(4), and the National Institute of Standards and Technology campus, Maryland(5),
have proven that populations of deer can be controlled with IC. These and other
studies have also shown that PZP is safe for contracepted deer.
Although
SpayVac™ meets the requirement for a single-dose, long-lasting
vaccine, successful use also requires the ability to treat a
large enough proportion of the population to be able to control
the number of animals.
(4) Naugle,
R.E., et al. 2002. Field testing of immunocontraception on white-tailed
deer (Odocoileus virginianus) on Fire Island National
Seashore, New York, USA. Reproduction Supplement 60:143-153.
(5) Rutberg, A.T., et al. in press. Effects of immunocontraception on a
suburban population of white-tailed deer Odocoileus virginianus. Biological
Conservation.
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