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PHYSIOLOGY INSTITUTE - MEDICINE SCHOOL
NATIONAL UNIVERSITY OF CÓRDOBA
ARGENTINA
“Chinchilla lanigera: endocrine and reproductive database for the optimization of
captive breeding”
INTRODUCTION
The Reproduction Laboratory is part of the Physiology Institute of the Medicine School,
National University of Córdoba (www.fcm.unc.edu.ar), and is integrated by a group of
biologists and medical doctors that are interested in the study of Reproductive Physiology of
mammals including man, mouse, bull and chinchilla.
Chinchilla is one of the species with major interest to our Laboratory and, since 1996, we
have been working in several aspects of their reproductive physiology.
We have developed and applied several techniques usually employed reproductive programs
for domestic species. These techniques can now be applied in farms in order to improve the
reproduction of the domestic chinchilla and to facilitate management strategies for the best
production rates.
Some of the techniques that we have successfully applied were:
Electroejaculation: in unanesthetized or anesthetized males, the multiple samples obtained
from each animal were employed for evaluating seminal quality. The effectiveness of the
methodology was 100%, an efficiency not previously reached. Sperm functional parameters
evaluated were: sperm concentration, motility, vitality, tail membrane integrity an acrosomal
status. Results demonstrated that the concentration and quality of the ejaculated sperm were
adequate for utilization in assisted reproduction methodologies (sperm motility and viability >
90 %).
A prerequisite for veterinary or biological studies, is to reduce to a minimum the stressful
factors associated to animal manipulation. Anesthesia can overcome this problem and would
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greatly facilitate electroejaculation of wild/caught chinchillas. However, the success with this
procedure is lower (~ 60%).
Related published articles:
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Activity
of
Chinchilla
laniger
spermatozoa
collected
by
electroejaculation
and
cryopreserved. Theriogenology 50:1239-1249, (1998).
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Functional activity of electroejaculated spermatozoa from anesthetized chinchilla
(Chinchilla lanigera). Research in Veterinary Science 78 (1): 93-97 (2004).
Sperm Cryopreservation: in order to store sperm without important damages to the sperm
functional activity, semen samples were stored at –196º C (liquid nitrogen) or for up to 72 hs
at 4ºC. A permanent source of readily available gametes requires the use of cryopreservation
techniques. The genetic superiority of some outstanding individuals could be preserved for
prolonged periods with the availability of these cryopreservation techniques.
With the cryoprotectant employed, functional activity of the gametes was preserved in a great
percentage, and values were similar to that obtained in fresh samples.
Related published articles:
-
Functional activity of epididymal Chinchilla lanigera spermatozoa cryopreserved in
different extenders. Research in Veterinary Science 64: 239-243 (1998).
-
Storage of Chinchilla lanigera semen at 4° C for 24 or 72 h with two different
cryoprotectants. Cryobiology 42, 301-306 (2001).
Hormonal tracking, non-invasively techniques were employed to detect changes in
endocrine activity related with reproduction or stress.
Related published articles:
-
A non-Invasive method for assessing adrenal activity in the Chinchilla (Chinchilla
Lanigera). Journal of Experimental Zoology. 1:301 (3): 218-27 (2004).
-
Assessment of endocrine testicular activity in Chinchilla lanigera by a non invasive
technique. Animal Reproduction Science (in press), 2004).
We believe that this techniques may be applied to solve some of the actual problems related
to the chinchilla industry, such as fur chewing, reproductive dysfunction (unsuccessful
matting), early pregnancy detection, the lack of rapid multiplication of the most valuable
individuals (i.e. artificial insemination).
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On the other hand, both Chinchilla species are almost extinct in the wild; only a few relict
populations remain in Chile and Argentina. Since 1973, Chinchilla spp. it’s included in the
Appendix I of CITES (CITES, 1973). Although protected in reserves, the number of individuals
is still declining without clear explanations.
It’s clear then, that successful conservation programs must utilize active management
techniques to enhance genetic diversity of the extant population, and that without active
management, funds, research and conservation, wild Chinchilla populations are likely to
become extinct in the near future.
Therefore, all the techniques validated and the basic data obtained about their reproductive
physiology would be of great relevance also for the conservation of the wild chinchilla.
At present, two PhD projects in the Laboratory are being conducted with chinchilla as subject
of the study. This is a very brief description of each:
MALE AND FEMALE ENDOCRINOLOGY DATABASE
In captivity, chinchilla reproduces throughout the year; the male remains fertile while only a
few female may come into estrus during summer; therefore, reproduction is limited by
seasonal breeding patterns. On the other hand reproductive rates in farms are generally low,
being the causes not well understood.
As well as in other species, environmental factors such as light hours, ambient temperature,
food availability and socials cues could affect reproduction of chinchilla. Reproductive
performance is also usually associated with season in nature as well in captivity. In breeding
facilities, where those factors can be controlled, little is known about the impact over
reproduction rates. Therefore, we consider that first, it is necessary to describe how such
factors could affect testicular and ovarian activities during the year in order to offer a
reproductive data-base.
Moreover, information related to reproductive physiology would aid in developing new
management strategies that would help for a more efficient use of both sexes by the fur
industry as well as would ensure the survival of the wild populations.
From a practical perspective, this study would help to design management strategies for
breeders in order to establish i.e., the best time for semen collection to preserve outstanding
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individual genetics, the best environmental conditions to reach maximum reproductive
capacity and finally, to establish the major basis for the accurate control of the sexual cycles.
With this in mind, our study is designed to: 1) describe functional testicular and ovary activity
in captive animals and 2) to evaluate in a monthly basis the sperm functional activity and the
hormonal profile of testosterone, estradiol and progesterone in urine and feces.
FUR CHEWING INCIDENCE AND PHARMACOLOGICAL TREATMENT
Fur chewing has been the object for many investigations and various opinions are given to
the probable cause of this condition. Factors that can induce fur chewing were supposed to
be as diverse as nutritional, genetic, environmental and/or neurological. Yet there has never
been a satisfactory explanation for this problem. Over the years, caring for Chinchillas have
improved greatly which has helped to reduce fur chewing incidence.
From studying Chinchillas it is easy to notice that some are more nervous than others. These
seem to be less likely to adjust to changes in their usual environment. Several factors such as
the weaker appearance of the animal, nervous behavior, unsatisfactory breeding and playing
with or wasting feed, all add to this animal being more susceptible to health and also chewing
problems.
It has been widely described that captivity stress can compromise health and decrease
reproductive function in many wild and domestic species. From all this observations, and from
studies in other domestic animals, it is likely that stress can be the major cause of fur chewing
in chinchillas. However, to our knowledge, no scientific studies have been conducted on this
topic.
On the other hand, the fur-chewing behavior has recently received attention and it was
described in many other domestic species such as mice, rat, guinea pig and hamster (were
this behavior is called “hair and whisker trimming”), parrots (“feather picking”), cats and dogs
(“obsessive compulsive disorder”). All this behaviors has been compared in their nature to the
human pathology known as trichotilomania; they correspond to a general description as
obsessive-compulsive spectrum disorders and in general are triggered by stress (i.e. physical,
psychological, social, etc) in susceptible individuals.
Therefore, we will try to determine whether or not fur chewing is a condition associated with
stress, what factors can induce the incidence of fur chewing, if the behavior is truly an
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obsessive-compulsive disorder, and if the individuals that present this problem have
reproductive dysfunction.
On the other hand, we will apply a pharmacological treatment, employing drugs usually
applied in veterinary science to alleviate and treat the above-mentioned behaviors in domestic
and companion animals.
We are convinced that with the obtained results, the validated techniques and the fulfillment of
the proposed objectives, we will conform a database on physiological aspects, essential for
evaluating individual males and females with respect to stress, fur chewing, reproductive
competence, and in the future for estrus cycles, ovulation timing, estrus length etc. Ultimately,
all these aspects will be useful for the development of protocols for artificial insemination and
ovulation induction.
Financial support from the Chinchilla Industry Council will significantly contribute to carry on
with those ongoing projects.
Dra. Marta Fiol de Cuneo
Professor and Chairman
Biol. Marina F Ponzio
PhD Fellow
Physiology Institute
Santa Rosa 1085
X5000ESU
Córdoba – Argentina
Ph/fax: 351-4332019
mponzio@mater.fcm.unc.edu.ar
Biol. Juan Manuel Busso
PhD Fellow