Caractéristiques et maîtrise de la fonction de reproduction chez les cervidés

Abstract

In recent years, cervidae breeding has been considerably developed in New Zealand, now becoming a profitable industry. Even though some cervidae (fallow deer, red deer) are being domesticated and bred commercially, other species and sub-species of cervidae are threatened by extinction in their natural habitat. The research studies that have been performed in order to better characterise and control the reproduction function of these ruminants are presented in this bibliographic study. It appears that as with our farm ruminants (ovines and caprines), the cervidae coming from temperate zones are generally characterised by the marked seasonality of their reproduction function. These seasonal variations of sexual activity are led by photoperiodic variations and allow the birth of the young at the end of the spring. With the cervidae, the differences between the periods of sexual activity and rest are much more marked in comparison with farm animals. The period of sexual activity is variable from one species to another (summer, autumn, or at the beginning of the winter) but is set for each species. The period of sexual rest translates important modifications in the gonadotrophin secretions and can notably be characterised by total aspermia in males. In the female, the state of anoestrus is deep and associated with an absence of ovulation. The length of gestation is also variable from one species to another but is set for each species. In the cervidae originating from subtropical zones and depending on the species, the variations in sexual activity are discreet, allowing a more or less homogenous distribution of births over the year, including when the animals are led to higher latitudes. For the cervidae species threatened by extinction, the use of reproduction biotechnology and assisted-procreation methods could on the long term help conservation programmes. The classical techniques of in vivo production of embryos based on multiple ovulation, artificial insemination and embryo transfer have been found to be difficult in the cervidae. In addition, current research is focussed on the development of techniques of in vitro production of embryos.