Abstracts - Deutsche Zoologische Gesellschaft

110 Behavioral Biology PostersP BB.11 - ENMaternal characteristics and litter size influence different immune parameters ofjuvenile laboratory rats.Geraldine Prager 1 , Volker Stefanski 2 , Heiko G. Rödel 11Universität Bayreuth; 2 Institut für Zoo- und Wildtierforschung (IZW) BerlinMany small mammals give birth to litters of highly variable sizes. Litter size i.e. the number of littersiblings, together with characteristics of the mother usually affect postnatal growth rates in altricialsmall mammals. In the laboratory rat, postnatal growth is comparatively lower in pups of larger littersbecause those pups get a smaller amount of milk per individual offspring. Mothers also transmitdifferent immune globulins und immune cells via milk supporting the development of the offsprings`immune system. In our study we tested for the effects of litter size, and of parity and body mass ofthe mother on some parameters of the cellular and functional immune system in juvenile Long-Evanslaboratory rats (Rattus norvegicus). Litter sizes were not manipulated and ranged between 2 and 18pups. Short before weaning, blood samples were taken from all pups of the litter and we quantifieddifferent immune cells and measured activity of complement system. We found consistent effects inalmost all immune parameters tested: Lymphocyte numbers and activity of complement system werenegatively correlated with litter size. All immune parameters tested were positively correlated withmaternal body mass and were higher in offspring of primiparous mothers (first litter cycle) than inpups of following litters. In conclusion our study points out that maternal characteristics as well aslitter size influence components of the immune system in juvenile rats around weaning.P BB.12 - ENThe impact of huddling on oxygen consumption of juvenile European rabbits underdifferent simulated weather conditionsMartin Seltmann 1 , Thomas Ruf 2 , Heiko Rödel 11Lehrstuhl Tierphysiologie, Universität Bayreuth; 2 Institut für Wildtierkunde und Ökologie, VeterinärmedizinischeUniversität Wien, ÖsterreichIn many small mammals, post-weaning young frequently stay in close body contact. Such interactionsamong juveniles may occur either in a positive social context, but may also entail thermalbenefits (huddling). Also juvenile European rabbits (Oryctolagus cuniculus L.) frequently show thisbehaviour during the first weeks after leaving the breeding burrow; this was evaluated by us inanother study under field conditions. This behaviour might buffer the negative influence of adverseweather conditions on the thermoregulatory costs of the juveniles. In order to test this, we comparedoxygen consumption of singly housed and pairs of young wild-type rabbits under three differenttemperatures, which reflected the range of ambient temperature conditions in the field. We ran theexperiments under dry and wet conditions where we sprayed the animals with a small amount of water(simulated rain). Ambient temperature and wetness of the fur strongly affected oxygen consumption,with the temperature-dependent increase in oxygen consumption being more pronounced whenthe animals` fur was wet. However, we did not find significant effects of huddling on the juveniles`oxygen consumption, either under cold, warm, dry or wet conditions. In conclusion our study doesnot support that close body contact among juvenile rabbits lowers the costs of thermoregulation. Werather believe that this behaviour may play a role in a social context.