“Chinchilla lanigera: endocrine and reproductive database for the optimization of captive breeding”
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 greatly facilitate electroejaculation of wild/caught chinchillas. However, the success with this procedure is lower (~ 60%).
Related published articles:
Activity of Chinchilla laniger spermatozoa collected by electroejaculation and cryopreserved. Theriogenology 50:1239-1249, (1998).
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).
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 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 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 CuneoBiol. Marina F Ponzio Biol. Juan Manuel Busso