Sandrine1308

Voici une autre étude, datant de 2000 sur un des impacts de la température de l'environnement donc du corps du hamster sur son alimentation (graisses saturées ou non). Pour une fois l'abstract est en anglais et a été traduit en français. En résumé, en environnement frais (sans être trop froid et donc sans rentrer dans le phénomène de torpeur hivernale), le hamster russe choisit naturellement un régime plus riche en graisses non saturées, et se remet à manger plus de graisses non saturées dès qu'il se trouve à des températures "d'été" (22-25°C). Cela démontre clairement que la température de son habitat en captivité a un impact, à minima, sur ses besoins alimentaires. Qu'en conséquence, je me dis qu'à priori, et à étudier plus avant, avoir la possibilité d'augmenter ou de diminuer la température de son habitat pourrait permettre d'adapter, à minima, le régime alimentaire de nos hamsters pour répondre à des situations spécifiques de santé de l'animal (diabète, obésité, maladie, maigreur, etc). C'est pour cela également que j'ai choisi de prendre un tapis chauffant pour mon futur terra à mettre sous le terra. Je pourrais l'enlever si non adapté. Voici l'étude complète et l'abstract (résumé des conclusions de l'étude) : Effect of temperature on preference for dietary unsaturated fatty acids in the Djungarian hamster (Phodopus sungorus) Sara M. Hiebert, Erin K. Fulkerson, Kirstin T. Lindermayer, and Sarah D. McClure Abstract: Previous studies have shown that hibernators preparing for winter prefer a diet rich in unsaturated fat. This study was designed to determine if a daily heterotherm, the Djungarian hamster (Phodopus sungorus), shows a similar preference when given simultaneous access to two diets, one rich in saturated fat and the other rich in unsaturated fat. In two experiments, hamsters that had been exposed to short days for 8–10 weeks were exposed to 8°C for 10 days. When half of these animals were moved to a warm environment (26–29°C), they developed a significantly lower preference for the unsaturated diet than controls that remained at 8°C (P < 0.01). This difference in preference disappeared when the experimental group was returned to 8°C (P = 0.4). Although mean body temperature (Tb) was significantly lower (mean difference = 0.35°C) in experimental animals in the cold environment, most animals did not enter daily torpor at any time during the experiment. Together, these results suggest that the large decreases in core Tb accompanying torpor, originally assumed to necessitate the incorporation of unsaturated fatty acids into cell membranes of hibernators and daily heterotherms, are not necessary to stimulate changes in food choice. Résumé : Des études antérieures ont démontré que les animaux qui entrent en hibernation préfèrent un régime riche en graisses non saturées. Cette étude a été entreprise dans le but de déterminer si un hétérotherme quotidien, le hamster Phodopus sungorus, manifeste cette préférence s’il a le choix entre deux régimes, l’un riche en graisses saturées, l’autre riche en graisses non saturées. Au cours de deux expériences, des hamsters préalablement exposés à des jours courts pendant 8–10 semaines ont été exposés d’abord à une température de 8°C pour 10 jours. Lorsque la moitié des animaux ont été placés dans un milieu chaud (26–29°C), ils ont montré une préférence moins marquée pour le régime riche en graisses non saturées que les hamsters témoins qui sont restés dans le milieu à 8°C (P < 0,01). Cette différence de préférence est disparue quand les animaux du groupe expérimental ont été retournés au milieu maintenu à 8°C (P = 0,4). Bien que la température corporelle moyenne (Tb) ait été significativement plus faible (différence moyenne = 0,35°C) dans le milieu froid, la plupart des animaux ne sont jamais entrés en torpeur quotidienne au cours de l’expérience. Dans l’ensemble, ces résultats indiquent que les diminutions importantes de la température corporelle qui accompagnent la torpeur, diminutions que l’on croyait nécessiter l’incorporation d’acides gras non saturés dans les membranes cellulaires des animaux en hibernation et des hétérothermes quotidiens, ne sont pas nécessaires à la stimulation des changements de choix alimentaires. [Traduit par la Rédaction] 1368 Introduction Hiebert et al. The effects of cold, as well as the adjustments made by organisms in response to cold exposure, may be observed at levels of organization ranging from the molecular to the organismal. At the level of the cell membrane, low temperature decreases membrane fluidity and may induce phase transitions, which may in turn affect cell function by affecting the activity of membrane-associated proteins, the mobility of molecules within the membrane, and the permeability of the membrane to water and ions (Cossins et al. 1987; Aloia 1988; Hazel 1995, 1997; Muramaki et al. 2000). Fluidity at a given temperature is decreased by the presence of saturated fatty acyl residues in the phospholipids that comprise the lipid bilayer and increased by the substitution of unsaturated fatty acids, which may be obtained in the diet (Mead et al. 1986; McMurchie 1988) or by enzymatic desaturation of existing fatty acids. The composition of lipids outside the plasma membrane may also be important because depot fats, which in vertebrates are deposited almost exclusively as triglycerides, need to be fluid to be metabolizable (Mead et al. 1986; Frank and Storey 1995). Here too, unsaturated fats tend to counteract the solidifying effects of low temperature. Heterotherms, animals that hibernate seasonally or enter daily torpor, are of particular interest with regard to lipid composition because body temperature (Tb) in the normothermic and torpid states differs by a median of 25°C in daily heterotherms and 37°C in seasonal hibernators (Geiser and Ruf 1995). Temperature changes of this magnitude would be expected to affect cell-membrane fluidity and lipid mobilization substantially. For hibernators, such as the goldenmantled ground squirrel (Spermophilus lateralis), the chipmunk (Eutamias amoenus), and the marmot (Marmota Can. J. Zool. 78: 1361–1368 (2000) 2000 NRC Canada 1361 Received October 13, 1999. Accepted April 20, 2000. S.M. Hiebert,1 E.K. Fulkerson, K.T. Lindermayer, and S.D. McClure. Biology Department, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081-1390, U.S.A. 1Author to whom all correspondence should be addressed (e-mail: shieber1@swarthmore.edu). flaviventris), consuming the appropriate dietary fatty acids also has indirect energetic advantages. Individuals consuming a diet high in unsaturated fatty acids have a greater incidence of hibernation, lower Tb during bouts of hibernation, lower metabolic rate, and (or) longer hibernation bouts than individuals of the same species consuming a diet low in unsaturated fatty acids (Geiser and Kenagy 1987, 1993; Geiser 1990, 1993; Frank 1992; Geiser et al. 1992, 1994; Florant et al. 1993; Thorp et al. 1994; but see also Frank and Storey 1995; Hill and Florant 2000). The necessity of altering lipid composition in seasonal hibernators is readily apparent because these animals are torpid for many months at a time. Although hibernators normally arouse periodically, most of the hibernation season is spent at very low Tb (Boyer and Barnes 1999). For daily heterotherms, however, the temporal pattern of torpor is different. Even though the propensity for entering daily torpor may be strongly seasonal, daily heterotherms, such as the deer mouse (Peromyscus maniculatus) and the Djungarian hamster (Phodopus sungorus), are normothermic for at least part of each day (Geiser and Ruf 1995). A priori, the need for altering lipid composition in the case of daily heterotherms is therefore not as clear as for hibernators, since daily heterotherms need to function at both high and low temperatures. Nevertheless, studies on deer mice (Geiser 1991), Djungarian hamsters (Geiser and Heldmaier 1995), and the marsupial Sminthopsis macroura (Withers et al. 1996) together demonstrate that individuals fed a diet high in polyunsaturated fatty acids (PUFAs) have significantly higher proportions of these fats in body tissues, including depot fat, total lipids in leg and brain, heart mitochondrial membranes, and brown adipose tissue. Furthermore, individuals consuming PUFA-rich diets increase energy savings during torpor by one or more of the following means: more frequent bouts of torpor, longer bouts of torpor, and lower metabolic rate during torpor. Although many studies have addressed the question of whether dietary fatty acid composition affects the torpor patterns of seasonal and daily heterotherms, far fewer have addressed the question of whether heterotherms confronted with a choice of diets containing different proportions of saturated and unsaturated fatty acids would exercise a preference for the one containing the seasonally appropriate fatty acid composition. In a study with ground squirrels (S. lateralis), Frank (1994) demonstrated that during the fattening period preceding hibernation, the animals preferred a diet containing a higher proportion of unsaturated fatty acids than animals held at high temperatures. The ability of daily heterotherms to exercise thermally appropriate dietary choice has not yet been reported. Methods General methods Maintenance and care of animals The Djungarian hamsters in this study were descendents of animals generously donated to us by Bruce Goldman, whose colony originated in the laboratory of Klaus Hoffmann. From birth, female hamsters were kept at 22 ± 2°C, under a photoperiod of 16 h light (L) : 8 h dark (D). After weaning, hamsters were housed in groups of two or three in opaque plastic cages (18 × 28 × 13 cm) lined with cedar shavings. When hamsters were moved to short-day conditions and ambient temperature (Ta) was reduced to 13°C or less, bedding was supplemented with cotton batting for added insulation. Except during experimental diet manipulation during the two experiments described below, hamsters were fed Purina 5008 rodent chow and provided with water ad libitum. Animal care and experimental methods used in these studies conform to the principles and guidelines of the Canadian Council on Animal Care, as set forth in the Guide to the Care and Use of Experimental Animals (1993). Radio transmitters and implantation surgery After individual calibration, radio-frequency transmitters (XMFH, Mini-mitter, Sunriver, Oregon) were implanted intraperitoneally in hamsters anesthetized with 85 mg/kg pentobarbital sodium (Nembutal , Abbott Laboratories) supplemented with methoxyflurane vapors (Metofane, Mallinckrodt) as needed. The abdominal wall was closed with absorbable suture (Vicryl, Ethicon) and skin incisions were closed with a surgical adhesive (Vetbond, 3M Animal Care Products). Nitrofurazone dressing, 0.2% (Fermenta Animal Health), was applied to the wound closure post surgically and acetaminophen with codeine phosphate solution (Barre National) was added to the water supply for several days as a postsurgical analgesic. Hamsters were kept at 22°C for 4–7 days after surgery and then returned to 13°C for an additional 5 days before the beginning of the experiment. Radio-frequency signals were collected, plotted, and analyzed using Dataquest software (Data Sciences International, St. Paul, Minnesota). Experimental diets Throughout each experiment, hamsters were simultaneously offered two diets. The diets were prepared by marinating Purina 5001 mouse chow (4.5% crude fat) in an amount of beef fat (high in saturated fat) or sunflower oil (high in unsaturated fat) sufficient to produce a 10% increase in pellet mass (Hilditch and Williams 1964; Gunstone et al. 1986; Table 1); this technique was previously used in experiments testing the effect of dietary fatty acids on torpor (Geiser and Kenagy 1987, 1993; Geiser 1991; Geiser et al. 1992, 1994; Geiser and Heldmaier 1995; Withers et al. 1996). Hereinafter, diets will be referred to simply as the unsaturated diet or saturated diet. After marination, experimental diets were stored at –4°C to prevent spoilage. Food hoppers were separated into two compartments by a wiremesh divider. Half the hamsters in each treatment group received the saturated diet on the left side of the hopper and the other half received it on the right side to control for the effects of location and (or) proximity on food choice. Each day, the pellets remaining in each compartment were weighed between 16:00 and 17:00, a time chosen because P. sungorus normally complete their daily bouts of torpor earlier in the day (Bartness et al. 1989). After weighing, pellets were added to the hopper to bring the total mass of pellets in each compartment to 20 g, well over the amount consumed daily ( 0.08 on all days), but experimental hamsters consumed significantly less than controls on every day in phase II (MWU, P < 0.0005 on each day). Preference for the unsaturated diet followed the predicted pattern. In phase I, the unsaturated diet comprised a mean 45.8 ± 1.5% of the total diet of all hamsters. In phase II, after the hamsters had been divided into treatment groups and the experimental group had been moved to 29°C, unsaturated diet accounted for a significantly lower proportion of the total diet in the experimental group (45.5 ± 5.1%) than in the control group (62.1 ± 2.3%) (MWU, P = 0.01) (Fig. 1). In day-by-day comparisons of the treatment groups, diet preference of experimental and control hamsters did not differ significantly on any day in phase I. In phase II, differences tended on some days toward significantly lower preference for the unsaturated diet by experimental hamsters than by controls, but there were no significant differences on any day, nor did the tendencies toward significance follow any clear temporal pattern (Fig. 1). Body mass did not change significantly from the end of phase I (26.9 ± 0.6 g for all hamsters) to the end of phase II (26.2 ± 0.6 and 26.4 ± 0.9 g for control and experimental 2000 NRC Canada 1364 Can. J. Zool. Vol. 78, 2000 hamsters, respectively) (Wilcoxon, P > 0.5 in both cases), suggesting that there were no changes in body mass that could be attributed to the saturation level of the diet. Experiment 2 Food consumption During phase II, mean total daily food consumption for all hamsters was 5.16 ± 0.14 g. As in phase II of experiment 1, total daily food consumption averaged over all of phase II was significantly lower in experimental hamsters at 29°C (3.12 ± 0.16 g) than in control hamsters remaining at 8°C (5.20 ± 0.16 g) (MWU, P < 0.0001). Averaged over all of phase III, total daily food consumption of experimental hamsters was again statistically indistinguishable from that of control hamsters (MWU, P = 0.07) (Fig. 2). Day-by-day comparisons of total food consumption showed that during phase I, there were no significant differences between treatment groups on any day (MWU, P > 0.05 on all days). During phase II, experimental hamsters consumed significantly less food than controls on all but 2 days (MWU, P < 0.002 for significant differences and P ³ 0.06 for nonsignificant differences). During phase III, total daily food consumption was significantly lower in experimental than control hamsters on days 1 and 3 (MWU, P < 0.003) but not on any of the remaining days (MWU, P ³ 0.02 in all cases), suggesting that adjustment of total food intake in a new thermal environment is not immediate but may take several days. During phase I, the mean percentage of unsaturated diet consumed by all hamsters over all 10 days was 72.2 ± 4.3%. During phase II, the mean percentage of unsaturated diet in the control group at 8°C remained in this range (68.5 ± 4.5%), whereas that of the experimental group at 29°C was significantly lower (46.5 ± 5.6%) (MWU, P = 0.005) (Fig. 2). In phase III, when experimental hamsters were returned to 8°C with the control hamsters, there was again no significant difference in diet preference between the control group (63.5 ± 3.6% unsaturated diet) and the experimental group (57.3 ± 6.5% unsaturated diet) (MWU, P = 0.83) (Fig. 2). Day-byday comparisons of diet preference between the two treatment groups showed no significant differences on any day in phase I. In phase II, a significantly lower preference for the unsaturated diet by the experimental hamsters than by the controls did not remain stable until after day 10 (Fig. 2). In phase III, significant differences were again absent on all days, suggesting that dietary adjustments made in response to a sudden shift to high temperature require longer exposure than dietary adjustments made in response to a sudden shift to low temperature. Body temperature In phase I, mean Tb of all hamsters was 36.45 ± 0.05°C. In phase II, however, mean Tb of the experimental group at 26°C (36.57 ± 0.09°C) was slightly but significantly higher than the mean Tb of the control group at 8°C (36.22 ± 0.08°C) (two-sample t test, P = 0.01) (Fig. 2). For the 20 hamsters for which at least partial data were available in phase III, there was again no significant difference in mean Tb between the control (36.37 ± 0.10°C) and experimental (36.32 ± 0.12°C) animals (two-sample t test, P = 0.79). In all three phases of experiment 2, temperature records showed only two bouts of torpor, here defined as excursions of Tb below 28°C (Heldmaier and Steinlechner 1981). Both of these bouts were exhibited by one hamster in the experimental group during phase II, when the experimental group was held at 26°C. Pelage and body mass Pelage color index of all 30 hamsters increased significantly (i.e., fur became lighter) from phase I (1.7 ± 0.1) to phase III (2.0 ± 0.2) (P = 0.04). There was no difference in fur color between treatment groups at the end of phase III (P = 0.8), indicating that the balanced fur color of the treatment groups that was present when the animals were assigned to treatment groups at the beginning of phase II persisted until the end of the experiment. There were no significant differences in body mass between the two treatment groups at any time during the experiment (ANOVA, P = 0.99), but the increase between initial body mass (before the experiment began (26.1 ± 0.5 g)) and subsequent measurements (29.4 ± 0.7 g at the end of phase I, 29.5 ± 0.7 g at the beginning of phase III, and 29.8 ± 0.6 g at the end of phase III) (P < 0.0001) was significant, suggesting that the addition of fat (either saturated or unsaturated) to the diet results in significant mass gain. Discussion The results of these experiments demonstrate that Ta influences diet choice in Djungarian hamsters exposed to short days in such a way that there is a greater preference for a diet high in unsaturated fatty acids at low Ta than at high Ta. Development of diet preference requires at least several days of exposure to a higher Ta and is reversible by returning the animals to a low Ta. Because the energy content of both lipid-enhanced diets was 20 kJ/g (Geiser and Kenagy 1987), the saturation level of dietary fats explains the observed preference better than direct energetic considerations. The potential benefits of this preference are that unsaturated fats, when incorporated into fat depots and cell membranes, should increase fat mobilizability and offset the viscosity-increasing effects of low temperature on cell membranes, respectively. Although a mechanism has not yet been elucidated, previous studies have demonstrated that incorporation of unsaturated fats into somatic tissues also has an indirect energetic benefit because an increase in unsaturated fatty acid content results in increased energy savings during torpor, both in hibernators (Geiser and Kenagy 1987; Geiser et al. 1992, 1994; Frank and Storey 1996) and in daily heterotherms (Geiser 1991; Geiser and Heldmaier 1995; Withers et al. 1996). The hamsters in the present study did not benefit in this way, however, because they did not enter torpor. Torpor is not necessary for the expression of dietary fatty acid preference It was originally hypothesized that the large decreases in Tb during hibernation and daily torpor necessitated adjustments to counteract the viscosity-increasing effects of cold on somatic lipids in fat depots and cell membranes (Raison 2000 NRC Canada Hiebert et al. 1365 and Lyons 1971; Geiser and Kenagy 1987; Geiser 1991). In general, one might propose that reduced physiological function, brought about by increases in membrane viscosity and (or) solidification of depot fats, could be the proximate cue that initiates desaturase activity and (or) stimulates changes in preference for unsaturated dietary fatty acids. The results of the present experiment, however, show that torpor is not necessary for the expression of temperature-influenced changes in preference for dietary-fat composition. This finding may be interpreted in several ways: (1) even very small decreases in Tb (in the present study, less than 0.5°C) are sufficient to stimulate a change in diet preference; (2) a large decrease in Ta (in this study approximately 20°C) is the proximate cue stimulating a change in diet preference; or (3) the regional heterothermy that develops in endotherms during cold exposure, in which skin and appendage temperatures fall well below core Tb (Irving et al. 1957), affects membrane function and (or) lipid mobilization sufficiently to stimulate a change in diet preference. In any case, this finding leads to the prediction that seasonal changes in preference for unsaturated dietary fats should be evident in a wide range of endotherms, not just in those entering daily torpor or seasonal hibernation. Low incidence of torpor Although the lack of torpor observed in this study was unexpected, it does not detract from the general conclusion that thermal environment affects dietary fatty acid choice. Nevertheless, this observation raises the question of why the animals in this study failed to enter torpor more frequently, as observed in other studies of short-day Djungarian hamsters (e.g., Heldmaier and Steinlechner 1981; Bartness et al. 1989; Geiser and Heldmaier 1995). We propose several explanations. First, one might propose that the animals did not have sufficient time to develop spontaneous daily torpor. Prior to each of the experiments reported here, however, hamsters had already been exposed to short days for 8 (experiment 2) or 10 (experiment 1) weeks, which should have been sufficient to induce the expression of torpor (Bartness et al. 1989). Second, the hamsters in this study were exposed to extremely long days (16 h L : 8 h D) before being introduced to short-day conditions in this experiment, and recent studies have shown that such a photoperiodic history may increase the incidence of short-day nonresponsiveness (Gorman and Zucker 1997). Because nonresponders fail to regress the gonads in response to short-day exposure, they continue to maintain high levels of reproductive hormones, such as prolactin and testosterone, which are known to inhibit daily torpor in P. sungorus (Ruby et al. 1993). The significant change in fur color of our animals, however, argues that the animals were responding to short days. Nevertheless, even the animals with the lightest pelage were not entering torpor. One explanation for this combination of observations could be that different components of the winter phenotype (e.g., pelage color and spontaneous daily torpor) are under separate control, so that some traits can be more responsive to short days than others (Hoffmann 1978; Wade and Bartness 1984; Hall and Lynch 1985; Blank and Desjardins 1986; Bartness and Goldman 1988; Smale et al. 1988; Gorman et al. 1993). Third, saturated fat in the diet has been shown to reduce the incidence of torpor in a hibernator (Geiser and Kenagy 1987) as well as in daily heterotherms (Geiser and Heldmaier 1995; Withers et al. 1996). In the experiments reported here, all animals consumed some of the saturated diet. Diet choice in the natural environment Must free-living rodents preparing for winter exercise dietary fatty acid choice in nature? The plants on which these rodents feed are constrained in similar ways by Ta, with the result that exposure to the cold induces an increase in PUFA content; overwintering plant parts, such as seeds, typically have higher PUFA content than other parts of the plant (Hilditch 1951; Gunstone et al. 1986). Thus, a change in diet could conceivably be accomplished without any choice on the part of the animal; it could simply continue eating whatever plant foods were available in the environment and these would increase in PUFA content as winter approached. Dietary shifts toward increased consumption of foods high in unsaturated fats in autumn, such as those reported for pygmy possums (Burramys parvus; Smith and Broome 1992), goldenmantled ground squirrels (Frank 1994), and chipmunks (Tevis 1953), may represent a passive process based primarily on availability in the environment. Only by comparing the composition of gut contents with the composition of foods available in the environment can behavioral preference be implicated in seasonal dietary shifts. It could also be argued that seasonal shifts in dietary preference are driven primarily by high reproductive requirements for protein rather than by fatty acid saturation. According to this argument, animal foods, which incidentally also contain higher proportions of saturated fatty acids, would be more strongly preferred in spring and early summer than in late summer and early autumn. There is evidence, however, that hibernators in nature may play an active role in selecting foods with enhanced unsaturated lipid content in preparation for winter. Yellowbellied marmots (Marmota flaviventris) are reported to extend their home range specifically to include the cow parsnip, Heracleum sp. (Armitage et al. 1976), the plant highest in PUFAs in the marmot’s natural environment (Florant et al. 1990). The present laboratory study is the first to show that daily heterotherms exercise active choice for dietary fatty acid saturation and that choice is influenced by Ta. The question of whether such choice is regularly exercised in nature has yet to be demonstrated. Unlike hibernators, many of which discontinue eating and rely primarily on body fat stores for energy during the winter, daily heterotherms continue to eat during the winter, in many cases consuming food that has been cached in or near the burrow. Previous considerations of food choice for caching have focused on factors such as energy content, nutritional value, perishability, and the energetic costs of acquisition and handling (Smith and Reichman 1984). Evidence from the present and other studies suggests that fatty acid saturation should be included as a criterion influencing food choice for caching. Interestingly, some of the least perishable foods (seeds) also tend to have the highest unsaturated fatty acid content; thus, preference that may previously have been attributed to low perishability may in fact be driven primarily by natural selection favoring the con- 2000 NRC Canada 1366 Can. J. Zool. Vol. 78, 2000 sumption of unsaturated fats by rodents in cold winter climates. Acknowledgements Cynthia Ristine and Rory Alarcon provided excellent animal care and Jessica Cuni oversaw experiment 1 during a holiday break. We are also grateful to Jocelyne Noveral, who assisted with project oversight, John Kelly, who kept our equipment working, and Phil Everson, who provided statistical consulting. The Swarthmore College Biology Department provided funding for supplies and animal care. Generous contributions from the Howard Hughes Medical Institute supported the purchase of the environmental chamber and Mini-mitter data-acquisition system. References Aloia, R.C. 1988. 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Pour l'aeration, je crois que c'est suffisant puisqu'il y a 4 rails de 5cm sur 100cm, ce qui fait 2000cm2 de surface d'aeration sur environ 15.000, soit plus de 13%. Nos habitations d'humains n'ont pas autant d'aeration que cela et le fait que ces rails soient amovibles me permettront d'aerer régulièrement comme on ouvre ses fenêtres. L'ouverture coulissante des façades de 40x100 permettra également une aération complémentaire et un renouvellement rapide d'air. La du forum.

il s'avere que pour le tapis chauffant, j'ai choisi de le mettre quand même en dépis du conseil contraire de Cheshou parce que le veto NAC de la clinique du 12ème m'avait conseillé de mettre une bouillote à Kunu lorsuq'elle était malade avec son problème de bajoues bouchées. Les hamsters ont beaucoup de mal à réguler leur température corporelle et cela plus encore lorsqu'ils sont malades... Et je me dis que ça pourra être utile si elle est malade, ce que je ne lui souhaite pas... Elle ne peut pas se bruler avec et il n'y a aucun fil electrique à l'interieur du terra, puisqu'il se trouve sous le terra. Pour le distrib à grillon, je n'ai peut être pas bien compris le message de Cheshou, mais je ne vois pas le mal que je causerais à Kunu en le mettant, excepté peut être qu'elle pourrait se mettre à chasser le grillon !!!!

Le terra est commandé, a y est !!! Je le recevrais dans 3 semaines, 1 mois. J'espère vraiment qu'il va être top et convenir à Kunu, c'est tout ce que je demande. C'est vraiment du sur-mesure que j'ai vu avec Michel. En résumé : 100x73x68 (h) * 3 bacs à litière différentes avec des passages de l'un à l'autre (22cm max de litière), séparés par 2 plaques en verre * une plateforme amovible au dessus de la litière, posée sur les 2 plaques, avec un décor plat "roche" et un trou (rectangle de 20cm sur 10cm) au milieu pour descendre dans la litière du milieu et l'aerer. Cette plateforme fait 70cm sur les 100cm pour laisser 15cm de chaque côté pour accéder à la litière et aérer celle-ci. * Un décor de fond en roche avec 3 plateformes en roche et un tronc + des deco (champignons, schistes, etc) : - une 1ère, grande de 35x35 environ, qui relie le fond et le côté gauche à 13cm de hauteur de la plateforme basse, - une 2ème longue de 60 et large de 10 environ qui sera au milieu dun fond à 18cm de hauteur de la plateforme basse, - une troisième, grande de 20cm (sur le fond) par 60cm sur le côté droit 23cm de hauteur de la plateforme basse, * un gros tronc de bois qui permettra à Kunu de monter sur la 1ère plateforme et inséré dans le decor du fond, * Un petit toboggan en bambou vernis (bambou de 6cm de diamètre, fendu au 2/3 du diamètre pour ne pas que Kunu puisse tomber sur le côté) qui reliera la 2ème plateforme à la litière, * 4 grilles d'aeration amovibles de 5cm de large : - 1 sous les vitre culissantes de la façade, - 3 sur le toit qui sera pour moitié recouvert (protection de la lumière et de l'effet loupe du verre) et moitié en verre transparent * un systeme d'éclairage infra-rouge, * un tapis chauffant de 15x28cm qui sera collé sous le terra et permettra d'augmenter la température au-dessus de 2-3°C en cas de besoin. Ainsi, elle disposera d'une surface d'environ : * Base (étage bas correspondant à la litière) : 100x73 = 7.300 cm2 * Plateforme au-dessus de la base litière : 70x73 (sur 30cm de haut) = 5.110 cm2, * plateforme 1 : 35x35 = environ 610cm2, * plateforme 2 : 10x60= environ 600cm2, * plateforme 3 : 60x20= 1.200cm2 Ce qui fait environ un total de : 14.820cm2 !!! Le tout posé sur un tapis mousse, lui-même posé sur une planche vernie à roulettes. Je n'en reviens pas moi-même.... En espérant que je n'ai pas commis d'erreur(s) majeure(s).... Et cela grâce à votre aide et vos infos. Maintenant comme on dit, WAIT AND SEE... Et j'ai quand même commandé le distributeur à grillons (taille 1cm environ le grillon, il y a plusieurs tailles de grillons), une boite de grillons, et l'aquagel et la nourriture pour grillons avec... Tant pis si les grillons se planquent et que Kunu ne les voient pas, je tente quand même. J'imagine que dans la nature, les hamsters les attrapent vivants. Peut être ais je tord, mais je ne vois pas la nuisance causée possible pour le hamster. Au pire, j'aurais une réserve à grillons adaptée avec leur nourriture et eau. J'ai également inclus un thermomètre avec 2 sondes que je peux placer, l'une dans la litière et l'autre plus haut pour contrôler la température dans le terra. Je vous tiens au courant et vous envoie des photos dès reception. Et JOYEUSES PAQUES A TOUTES ET TOUS !!!!

Mille merci à vous...

La pauvre !!!! Abandonnée dans le salon... J'espère que tu vas la sauver de cette facheuse situation !!! ;)

Une autre étude trouvée, datant de 2009 et très interessante également, et qui a une connexion avec l'autre étude sur le comportement agressif du male hamster russe en hiver : la période hivernale et ses courtes journées. En résumé, l'abstract dit que les hamsters russes sont moins actifs en hiver, lorsque les périodes de jour sont courtes, ils diminuent leurs dépenses d'énergie et corrélativement mangent moins, donc maigrissent. Cette étude a été réalisée avec des hamsters en captivité sous des conditions de lumière artificielle. Donc, j'en déduirais, au conditionnel of course, que nos chouchous sont sujets à ce genre de modification de comportement lorsque la lumière artificielle de nos habitats ne vient pas ou prou modifier la durée de lumière du jour. Voici l'abstract en question, toujours en anglais je sais, mais bon je n'y souis pour rrrrriennnnn..... Effects of photoperiod on daily locomotor activity, energy expenditure, and feeding behavior in a seasonal mammal Amy Warner, 1,2 Preeti H. Jethwa,1 Catherine A. Wyse,3 Helen I'Anson,4 John M. Brameld,2 and Francis J. P. Ebling1 Schools of 1Biomedical Sciences and 2Biosciences, University of Nottingham, Nottingham, United Kingdom; 3School of Biological Sciences, University of Aberdeen, Zoology Building, Aberdeen, United Kingdom; and 4Biology Department, Washington and Lee University, Lexington, Virginia Corresponding author. Address for reprint requests and other correspondence: A. Warner, Univ. of Nottingham, School of Biomedical Sciences, Queen's Medical Centre, Nottingham, UK (e-mail: mbxaw2@nottingham.ac.uk ). Received May 19, 2009; Accepted March 3, 2010. Copyright 2010 the American Physiological Society Abstract The objective of this study was to determine whether the previously observed effects of photoperiod on body weight in Siberian hamsters were due to changes in the daily patterns of locomotor activity, energy expenditure, and/or feeding behavior. Adult males were monitored through a seasonal cycle using an automated comprehensive laboratory animal monitoring system (CLAMS). Exposure to a short-day photoperiod (SD; 8:16-h light-dark cycle) induced a significant decline in body weight, and oxygen consumption ( O2), carbon dioxide production ( CO2), and heat production all decreased reaching a nadir by 16 wk of SD. Clear daily rhythms in locomotor activity, O2, and CO2 were observed at the start of the study, but these all progressively diminished after prolonged exposure to SD. Rhythms in feeding behavior were also detected initially, reflecting an increase in meal frequency but not duration during the dark phase. This rhythm was lost by 8 wk of SD exposure such that food intake was relatively constant across dark and light phases. After 18 wk in SD, hamsters were transferred to a long-day photoperiod (LD; 16:8-h light-dark cycle), which induced significant weight gain. This was associated with an increase in energy intake within 2 wk, while O2, CO2, and heat production all increased back to basal levels. Rhythmicity was reestablished within 4 wk of reexposure to long days. These results demonstrate that photoperiod impacts on body weight via complex changes in locomotor activity, energy expenditure, and feeding behavior, with a striking loss of daily rhythms during SD exposure.

J'ai lu que les excréments - urines ne dérangeaient pas les hamsters qui parfois s'en nourrissent car remplis d'éléments nutritifs pour eux, en conséquence je crois que c'est normal pour lui, ou plutôt qu'il n'y a pas de pb à déposer son stock à côté de ses pipis. Et cacher son stock dans le sable constitue une bonne planque pour lui, enfin une planque sur peut être plusieurs dans son habitat car ils peuvent en avoir un peu partout. Enfin bon, je ne détiens pas la vérité, mais ce pourrait être un élément de réponse à faire confirmer ou non par les super masterqueen du forum.

snif snif... je vais donc la laisser de côté.... c'est bien dommage... J'aimerais comprendre la différence de difficulté - danger - entre 20 cm de litière à remonter dans cette tour et 20cm de litière à remonter dans un terra par exemple. Les parois sont glissantes elles aussi. Est ce quand il tente de remonter qu'il se coince en se bloquant buttant au toit, en faisant le tour car le trou est au milieu ? La sortie basse est grande et fait 11 cm de large sur un demi cercle de rayon 5cm. J'ai vraiment du mal à comprendre mais prendrait néanmoins mes précautions en ne mettant pas cet objet dans le terra de Kunu. Mais peut être essayer de l'observer dedans quand je la sors pour voir le blème. En tous les cas, merci à toi Mio.

je voulais dire non.... ooouppppsssss..... pour le résineux.... je n'ai écris que des co.....ies. Corrigées fort heureusement par Mio....

As tu des détails stp Mio sur les circonstances des accidents ? Car elle me semble plutôt bien faite, avec grosse ouverture en bas et en haut et ne fait que 20 cm de haut. Cela dépent'il du type de litière, de la hauteur de litière mise dedans ???? Je suis perplexe.... mais attentive à ton information bien sûr. Merci à toi.

si c'est du résineux oui : sapin, pin. Sinon, c'est ok. Vérifie avec Aoko, une des masterchef du forum.;) ou avec Mio, Shechou et j'en oublie plein...

Nouvelle étude super interessante trouvée sur le net sur le comportement agressif des femelles hamsters russes et campbell lorsqu'elles ont des petits. Les femelles russes sont plus agressives que les campbell. Les males campbell jouent un rôle essentiel avec les petits, pas les males russes. Cependant, ils ont noté que laisser le mâle avec la femelle diminue significativement l'agressivité de la femelle lorsqu'elle a des petits chez le hamster russe et campbell. Les types d'attaque portées sont différents chez le campbell et chez le russe. Les coups portés par le campbell sont des attaques de type "boxing" (difficile à traduire mais compréhensible même en anglais) à 50% et 50% de morsures sur le ventre et les flancs. Pour le hamster russe, les attaques sont à mini 90% des morsures sur le ventre et les flancs. De vrais tites guerrieres les nanas russes !!! Je vous joins l'étude ci-dessous en anglais, bien longue, mais l'abstract du début (résumé) est assez concis et suffisant. AGGRESSIVE BEHAVIOR Volume 31, pages 294–302 (2005) High Maternal Aggression in Dwarf Hamsters (Phodopus campbelli and P. sungorus) Stephen C. Gammie1 and Randy J. Nelson2 1Department of Zoology and Neuroscience Training Program, University of Wisconsin, Madison, Wisconsin 2Departments of Psychology and Neuroscience, The Ohio State University, Columbus, Ohio : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : The defense of offspring, termed maternal aggression, is a highly conserved behavior in mammals, including rodents. This study examined relative levels of maternal aggression in two closely related dwarf hamster species, Phodopus campbelli and P. sungorus, that normally inhabit high latitude, boreal environments. When tested with first litters and with the breeder male remaining with the female (for P. campbelli the male is necessary for successful rearing of offspring), both species exhibited high levels of maternal aggression with average duration of aggressive behavior480 sec for a 10 min test. For P. sungorus, males are not required to rear offspring. P. sungorus females with either one or multiple litters (singly housed after impregnation) exhibited significantly higher levels of aggression (4300 sec) relative to females co-housed with the sires. In terms of species differences in attack style, P. campbelli exhibited a boxing or clawing strategy forB50% of total attack time, but for P. sungorus, this form of attack occurredo5% of the time. For P. sungorus, attacks to the vulnerable belly and flank constituted490% of all attacks, but these regions were attacked B50% of the time for P. campbelli. A survey of levels of maternal aggression of rodents in other genera suggests that maternal aggression in Phodopus is at the high end of the spectrum. Results of this study suggest that the presence of the breeder male may actually suppress aggression in P. sungorus. This fact, as well as its high level of aggression and its distant relationship to mice and rats, suggest P. sungorus as a possible model for future studies on the neurobiological basis of maternal aggression. The relationship between the high rates of maternal aggression and life history strategy in Phodopus is discussed. Aggr. Behav. 31:294–302, 2005. r 2005 Wiley-Liss, Inc. : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : Keywords: aggression; Phodopus; nest defense; maternal behavior; parental behavior INTRODUCTION The protection of offspring in mammals can include fierce aggression against intruders, termed maternal aggression. In rodents, infanticide by unrelated conspecifics occurs and aggression (including biting and attacking) towards an intruder is required to protect the Grant sponsor: National Institute of Health; Grant number: MH 57760 (to R.J.N.); Grant sponsor: National Institute of Mental Health National Research Service Award MH; Grant number: 12371–01 (to S.C.G.). nCorrespondence to: Stephen C. Gammie, 1117 W. Johnson St. Department of Zoology, University of Wisconsin, Madison, WI 53706. E-mail: scgammie@wisc.edu Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/ab.20087 r 2005 Wiley-Liss, Inc. pups [Agrell et al., 1998; Wolff 1985, 1993]. Additionally, mouse strains that exhibit high levels of infanticide toward non-related offspring (such as wild house mice and outbred mice) also exhibit high levels of maternal aggression [Parmigiani et al., 1999]. In bank voles (Clethrionomys glareolus) experimental increase in litter size elevates maternal aggression, suggesting that in some rodent species, the level of parental investment also influences maternal aggression [Koskela et al., 2000]. Decreased pup mortality is correlated with increased wounding of the intruder in common voles (Microtus arvalis) [Heise and Lippke, 1997]. These findings indicate an adaptive role of maternal aggression in the protection of offspring. Maternal aggression, then, likely represents an evolutionary trade-off, where expression of the behavior can bring harm to the dam, but it can also dramatically increase the survival and fitness of the offspring [Agrell et al., 1998; Heise and Lippke, 1997; Maestripieri, 1992]. In addition to the rodent species listed above, maternal aggression has been studied in rats and mice, including wild and transgenic mice (for review, see Lonstein and Gammie, 2002); prairie voles (Microtus ochrogaster) [Gammie and Nelson, 2000; Villalba et al., 1997]; and Djungarian hamsters (Phodopus campbelli) [Vasilieva and Sokolov, 1994]. Only latency to attack and percent of time aggressive were documented for P. campbelli. Although an understanding of the neurobiological basis of maternal aggression is being developed in rats and mice [Lonstein and Gammie, 2002], the identification of an additional rodent species (ones distantly related to mice and rats) as a model for studying maternal aggression would provide an excellent opportunity for determining what elements of maternal aggression circuitry are conserved evolutionarily within rodents. The presence of high levels of maternal aggression would be an important criterion for a model system. Phodopus campbelli and P. sungorus, are two related species of dwarf hamster that inhabit high northern latitudes (B50 degree N latitude for both species). For P. campbelli, the mean monthly temperatures never exceed 15 1C, the mean temperatures in January are below
30 1C, and more than half of the annual 210 mm rainfall occurs in July and August [Wynne-Edwards, 1998]. For P. sungorus, the average temperature never falls below
20 1C for any month, and the average rainfall is twice that for P. campbelli [Wynne-Edwards, 1998]. It has been proposed that because of the relatively difficult reproductive environment and short breeding season, as a genus, Phodopus has the most compressed reproductive cycle of any mammal [Newkirk et al., 1997]. Within 36 days of first mating, one litter can become independent, a second litter can be born, and a third litter can be conceived [Newkirk et al., 1997; Parkening and Collins, 1991]. For P. campbelli the presence of the sire is critical for successful rearing of offspring in its environment, whereas for P. sungorus the presence of a sire is not critical. In P. campbelli sires assist during parturition [Jones and Wynne-Edwards, 2000] and help the dam to dissipate heat [Wynne- Edwards, 1998]. The correlation of maternal aggression with levels of investment in offspring (described above) and the limited number of pups produced each year (because of the life history and compressed reproductive cycle of Phodopus) lead to speculation that Phodopus may exhibit high levels of maternal aggression. The aim of this study was to examine maternal aggression in this genus to determine whether Phodopus may be a model system for studying the neurobiological basis of maternal aggression in future studies. Given the differences in the role of sires between the two species, it was also important to determine whether, and if, rearing conditions affected levels of maternal aggression in P. sungorus. Maternal Aggression in Dwarf Hamsters 295 METHODS Animals and Husbandry Adult dwarf hamsters (P. campbelli and P. sungorus) from breeding colonies were used in this study. Colonies were originally established from animals obtained from Katherine Wynne-Edwards (Queens University, Kingston, ON, Canada). Before pairing, animals were group housed with same-sex siblings. Paired animals were housed in polypropylene cages (27.87.513 cm) in a colony room with constant temperature and had constant access to food and tap water. All animals were housed in the same room in LD conditions with a reverse 15:9 light/dark cycle (lights on 2400h Eastern Standard Time). Males are required for the rearing of P. campbelli offspring, so breeder males remained housed with females during lactation. For P. campbelli, 13 lactating females (B2 months old, 1st litter) were tested for maternal aggression. For P. sungorus, three different groups were tested for maternal aggression. 1) 13 lactating females (B2 months old, 1st litter) with breeder males housed with females during lactation (conditions identical as for P. campbelli); 2) 4 lactating females (B2 months old, 1st litter) with breeder males removed from home cage after females became pregnant; 3) 11 lactating females (B6 months old, multiple litters—mean=6.1) with breeder males removed from home cage after females became pregnant. Maternal Aggression Behavioral Testing and Analysis On the 8th day postpartum, the pups (and sire, if present) were removed from the home cage and each female was exposed to a group housed, sexually naive intruder male of the same species (B2 months old) for 10 min between 0800 and 1200 h. In other rodents, peak maternal aggression occurs between day 4 and day 10 postpartum [Svare, 1990]. Intruder males were never used more than once per day, were used forB3 tests each, and did not show aggression towards dams. The pups (and sire) were removed from the cage 3 min prior to the female behavioral test and each test session with an intruder male was recorded on videotape and subsequently analyzed off-line to quantify aggressive behaviors by the female. In mice and hamsters, removal of the pups from a mother just before an aggressive test does not diminish the expression of maternal aggression [Siegel et al., 1983; Svare et al., 1981]. All analyses of behavioral testing were performed by a single individual who was uninformed about experimental conditions and treatments. Video analysis involved using pen and paper and stopping and starting the tape for each attack event. The following features were recorded for each test: latency to first attack, total number of attacks, and total time in aggressive encounters. Further, the form or site of attack was recorded for each attack including whether the attack involved clawing/boxing (directed towards the head) or involved bites to a particular part of the body of the intruder, subdivided into the head/neck, flank, or belly regions. Clawing/boxing occurred when the animal was in an upright position and would either throw single jabs with one paw or throw in quick sequence alternating paws towards the head of the intruder. In most cases, the clawing/boxing did not result in direct contact with the intruder. In these studies, all forms of aggression described above were combined to determine mean time aggressive and latency to first attack was determined from the onset of the test to the first appearance of any form of aggression that was quantified. 296 Gammie and Nelson STATISTICAL ANALYSIS For statistical analysis of behavioral differences among the three P. sungorus groups, a one-way ANOVA was used. If statistical differences were found, pairwise comparisons were made using a multiple comparison pairwise procedure (Student-Newman-Keuls method), for normally distributed data. If the data were not normally distributed, then Dunn’s method for pairwise comparisons was used. For four tests, maternal aggression testing was terminated early due to wounding of the intruder. In each case, the number of attacks and time aggressive was prorated for what would have been a full 10 min test. However, if these numbers exceeded the highest numbers for that group, the individual was assigned instead the maximum for that group to maintain a conservative estimate. In each of the four cases, the prorated amount of aggression exceeded the highest levels assigned for a full 10 min test, so the more conservative estimate was used. Additionally, the percentage of total time attacking was determined for each individual and group was also examined. In the case of time to first bite, if an animal was not aggressive, a time of 600s was assigned (the maximum possible for the test). Mean differences were considered significant if po0.05. RESULTS Phodopus campbelli Twelve out of 13 P. campbelli females exhibited aggression (93%) (Fig. 1A) and the mean latency to first attack was B60 sec (Fig. 1B). Animals showed high levels of aggression with the mean number of attacks greater than 20 (Fig. 1C) and the mean time aggressive greater than 80 sec (Fig. 1D). The majority of attacks took the form of clawing or boxing the intruder (B50% of the total attack time), but attacks to the flank, belly, and head/neck Fig. 1. Levels of maternal aggression in P. campbelli in terms of A) % aggressive; B) time to first attack; C) number of attacks; and D) total time aggressive. Bars represent means7S.E.M. E) provides a percentage breakdown of total aggression by either the manner of attack (clawing/boxing towards the head of the intruder) or the site of biting attacks (flank, head/neck, or belly region of the intruder). Maternal Aggression in Dwarf Hamsters 297 region were also exhibited (Fig. 1E). For the test that was stopped early due to wounding of the intruder, the female attacked the male for 153 out of 168 sec. The mean percentage of total test time spent attacking the intruder was 13.177.1. In terms of number of pups, P. campbelli had an average litter of 5.370.47. Phodopus sungorus P. sungorus females that remained co-housed with the breeder male (as were P. campbelli females) also exhibited high levels of maternal aggression. Eleven of 13 females exhibited maternal aggression (Fig. 2A), the mean number of attacks were B5 (Fig. 2C), and the mean time aggressive was greater than 85 sec (Fig. 2D) for the 10 min test. The mean percentage of total test time spent attacking the intruder was 15.776.1. In terms of number of pups, P. sungorus had an average litter of 5.570.31. Removal of the male after impregnation in P. sungorus, though, resulted in a significant elevation of maternal aggression in three measures of aggression. In terms of time to first attack, females with the first litter with the mate removed attacked in a significantly shorter period of time than first litter females with the male co-housed (Fig. 2B). Both females with the first or multiple litters exhibited a higher mean number of attacks relative to first litter females with the breeding male co-housed (Fig. 2C). Further, mean time aggressive was Fig. 2. Levels of maternal aggression in P. sungorus in terms of A) % aggressive; B) time to first attack; C) number of attacks; and D) time aggressive for three different treatments: (1) 1st litter with breeder male remaining in home cage (except during testing) (white bars); (2) 1st litter with breeder male removed from home cage following impregnation of female (black bars); and (3) females with multiple litters with breeder male removed from home cage after impregnation of female (hatched bars). Bars represent means7S.E.M. E) provides a percentage breakdown of total aggression by either the manner of attack (clawing/boxing towards the head of the intruder) or the site of biting attacks (flank, head/ neck, or belly region of the intruder). n=Po0.05; nn=Po0.01; one-way ANOVA. 298 Gammie and Nelson significantly higher for females from either group with the breeder male removed relative to first litter dams with the breeder male co-housed (Fig. 2D). No differences were observed in any of these measures between first and multiple litter dams when the breeder male was removed following impregnation. Three tests were terminated early due to wounding of the intruder male. For all three females it was their first litter and the mated male had been removed following impregnation of the female. For these three tests, the time attacking the male out of the total test duration was: 126/130 sec; 220/233 sec; and 170/174 sec. The mean percentage of total test time spent attacking the intruder was 52.076.6 for females with first litters and the pups removed and 63.677.6 for females with multiple litters and the male removed. In P. sungorus, belly and flank were the predominant sites of attacks (Fig. 2E) and there were no significant differences between the three groups in terms of percentage of attacks towards different regions (P40.05, one-way ANOVA). DISCUSSION P. campbelli and P. sungorus exhibited comparable high levels of maternal aggression (mean time aggressive480 sec for both) when the mated males remained co-housed with the females. The main distinction between the two species was observed in the pattern of attack. For P. campbelli, the majority of attacks involved clawing or boxing the intruder, but for P. sungorus (across all three groups), clawing or boxing comprised B4% of the attacks (Figs. 1E and 2E). In contrast, for P. sungorus (across all three groups) B93% of the attacks hit either the belly or flank region. It is difficult to speculate why differences in attack style exist between these species. P. sungorus females normally mate successfully with multiple males, dominate males, and form stable intra-sexual dominance hierarchies, whereas P. campbelli females remain in stable socially-monogamous relationships [Wynne-Edwards and Lisk, 1987]. The differences in attack approach could relate to the different social structure or it could have developed as a result of genetic drift and isolation of the two species. Males of P. campbelli, but not males of P. sungorus, assist in the delivery and care of pups [Scribner and Wynne-Edwards, 1994; Wynne-Edwards and Lisk, 1987]. The continued presence of P. sungorus males in the home cage following impregnation does not affect pup survival [Wynne-Edwards, 1998; Wynne-Edwards and Lisk, 1987]. However, results suggest that although the presence of the male does not alter pup survival, it likely has a significant negative effect on the full expression of maternal aggression. In terms of latency to attack, number of attacks, and mean time aggressive (Figs. 2B–2D), maternal aggression was elevated in females housed singly, compared to those that remained housed with their mate, even if all other test conditions, including litter number, were identical. Application of stressors to mice decreases levels of maternal aggression [Maestripieri et al., 1991; Pardon et al., 2000], leading to speculation that the lower levels of maternal aggression in P. sungorus females that remained co-housed with the breeder males may reflect an elevated stress response in the dams produced by the male. The extent to which glucocorticoid levels in lactating females are affected by the continued presence of a mated male, however, requires further studies. This study did not test a group of females with multiple litters in which the sire remained with the dam, so therefore we cannot determine whether it was lack of the sire or the effect of multiple litters that contributed to the high levels of maternal aggression in these dams. One Maternal Aggression in Dwarf Hamsters 299 additional caveat is that P. sungorus females that remained co-housed with males may have been pregnant. Postpartum estrus occurs onBpostpartum Day 0, so at the time of testing the dams may have been in the early stages of gestation and the hormonal changes due to pregnancy might have altered aggression. Whether or how pregnancy might influence levels of maternal aggression in P. sungorus would need to be determined in future experiments. Relative Maternal Aggression Between the Genus Phodopus and Other Genera Phodopus exhibited high levels of maternal aggression (80–300 sec for a 10 min test). It is difficult to conduct a meta-analysis of levels of maternal aggression across a range of rodent species because of variability in testing procedures (e.g., duration of test), scoring procedures (e.g., measures of aggression analyzed), intruder characteristics (size, sex, and age), and housing conditions (including light cycles). Additionally, for rodents that were originally caught from the wild, the duration or number of generations in captivity varies. The species in this study have been maintained in the laboratory since 1990. Yet another source of variability is the test date during lactation. For some species, such as Syrian hamsters (Mesocricetus auratus), test day does not influence levels of aggression [Siegel et al., 1983], yet for other species, including mice, peak aggression occurs between postpartum days 4 and 10 [Svare, 1990]. Given these caveats, though, the levels of maternal aggression in both Phodopus species are at the high end compared with rodents in other genera. For example, for a 10 min test, the following mean durations of maternal aggression have been reported for the following species or strains: C57 mice, from 20 sec to 35 sec [Gammie et al., 2000; Gammie and Nelson 1999]; outbred CD–1 mice, B30 sec [Ferrari et al., 2000]; wild mice (fourth generation in lab), B150 sec, [Ferrari et al., 2000]; prairie voles, B40 sec [Gammie and Nelson, 2000]; bank voles, B40 sec on day 3 of lactation and B20 sec on day 8 [Koskela et al., 2000]; and rats, B35 sec [Flannelly et al., 1986]. Unfortunately, for a large number of studies on maternal aggression in rodents, the total time aggressive by the female is not reported. Similar to our findings, the previous study on maternal aggression in P. campbelli reported a latency to first attack of 84 sec and all females exhibited aggression [Vasilieva and Sokolov, 1994]. As indicated above, though, other measures of aggression were not examined in that study. For maternal aggression in Syrian hamsters, B20 attacks for a 10 min period were reported for three studies [Siegel et al., 1983; Wise, 1974; Wise and Pryor, 1977]. These numbers are consistent with the number of attacks seen for the two hamster species in this study. However, because those studies on hamsters did not report the mean time aggressive, it is difficult to know whether overall levels of aggression were similar between the dwarf and Syrian hamsters. In many rodent species (for example, prairie deer mice and prairie voles), non-lactating females also exhibit aggression, but the intensity is far less than for maternal females [Ayer and Whitsett, 1980; Bowler et al., 2002]. Additionally, most studies on non-maternal aggression report either latency to attack or an aggression score, but not mean time aggressive. Therefore, comparisons of levels of maternal aggression in Phodopus to other forms of female aggression in different species is difficult. Phodopus as a Model for Studies of Maternal Aggression Findings of high maternal aggression in Phodopus are consistent with the hypothesis that with elevated parental investment and subsequent increased direct fitness per offspring, maternal aggression increases. Given the high levels of maternal aggression (4300 sec mean 300 Gammie and Nelson time aggressive, depending on condition, for a 10 min test), P. sungorus may prove to be an ideal model for studies of the neural basis of maternal aggression. Additionally, the relatively stable number of offspring and short gestation time in P. sungorus would act to decrease variability in other maternal behaviors and to provide rapid resources for neurobiological analysis. From a comparative perspective, studies of Phodopus are extremely useful because they are distant relatives to mice and rats (the subjects of most studies on maternal aggression). Thus, P. sungorus may provide an opportunity as an outgroup to test any hypothesis generated in mice and rats and allow for an examination of whether or how, with conserved behaviors, the neural basis of that behavior is conserved. Additionally, further comparisons between P. sungorus and P. campbelli could be made to determine the neural basis for the different forms of attacks used by two closely related species. ACKNOWLEDGMENTS The authors thank Kyle Blake, Marvin Chang, Justin Friske, Steve Kinsey, and Lindsay Theis for technical assistance. REFERENCES Agrell J, Wolff JO, Ylonen H. 1998. Counter-strategies to infanticide in mammals: costs and consequences. Oikos 83:507–517. Ayer ML, Whitsett JM. 1980. Aggressive behaviour of female prairie deer mice in laboratory populations. Anim Behav 28 Pt 3:763–771. Bowler CM, Cushing BS, Carter CS. 2002. Social factors regulate female-female aggression and affiliation in prairie voles. Physiol Behav 76:559–566. Ferrari PF, Palanza P, Parmigiani S. 2000. Does fear modulate defensive and offensive types of maternal attack in mice? Aggress Behav 26:193–203. Flannelly KJ, Kemble ED, Blanchard DC, Blanchard RJ. 1986. Effects of septal-forebrain lesions on maternal aggression and maternal care. Behav Neural Biol 45:17–30. Gammie SC, Huang PL, Nelson RJ. 2000. Maternal aggression in endothelial nitric oxide synthasedeficient mice. Horm Behav 38:13–20. Gammie SC, Nelson RJ. 1999. Maternal aggression is reduced in neuronal nitric oxide synthase-deficient mice. J Neurosci 19:8027–8035. Gammie SC, Nelson RJ. 2000. Maternal and matinginduced aggression is associated with elevated citrulline immunoreactivity in the paraventricular nucleus in prairie voles. J Comp Neurol 418:182–192. Heise S, Lippke J. 1997. Role of female aggression in prevention of infanticidal behavior in male common voles, Microtus arvalus (Pallas, 1779). Aggress Behav 23:293–298. Jones JS, Wynne-Edwards KE. 2000. Paternal hamsters mechanically assist the delivery, consume amniotic fluid and placenta, remove fetal membranes, and provide parental care during the birth process. Horm Behav 37:116–125. Koskela E, Juutistenaho P, Mappes T, Oksanen TA. 2000. Offspring defense in relation to litter size and age: Experiment in the bank vole Clethrionomys glareolus. Evol Ecol 14:99–109. Lonstein JS, Gammie SC. 2002. Sensory, hormonal, and neural control of maternal aggression in laboratory rodents. Neurosci Biobehav Rev 26:869–888. Maestripieri D. 1992. Functional aspects of maternal aggression in mammals. Can J Zool 70:1069–1077. Maestripieri D, Badiani A, Puglisi-Allegra S. 1991. Prepartal chronic stress increases anxiety and decreases aggression in lactating female mice. Behav Neurosci 105:663–668. Newkirk KD, McMillan HJ, Wynne-Edwards KE. 1997. Length of delay to birth of a second litter in dwarf hamsters (Phodopus) - evidence for post-implantation embryonic diapause. J Exp Zool 278:106–114. Pardon M, Gerardin P, Joubert C, Perez-Diaz F, Cohen- Salmon C. 2000. Influence of prepartum chronic ultramild stress on maternal pup care behavior in mice. Biol Psychiatry 47:858–863. Parkening TA, Collins TJ. 1991. Reproduction, pregnancy, and circulating reproductive hormones in the lactating Siberian hamster (Phodopus sungorus). J Exp Zool 257:401–407. Parmigiani S, Palanza P, Rogers J, Ferrari PF. 1999. Selection, evolution of behavior and animal models in behavioral neuroscience. Neurosci Biobehav Rev 23:957–969. Maternal Aggression in Dwarf Hamsters 301 Scribner SJ, Wynne-Edwards KE. 1994. Moderate water restriction differentially constrains reproduction in two species of dwarf hamster (Phodopus). Can J Zool 72:1589–1596. Siegel HI, Giordano AL, Mallafre cm, Rosenblatt JS. 1983. Maternal aggression in hamsters: effects of stage of lactation, presence of pups, and repeated testing. Horm Behav 17:86–93. Svare B. 1990. Maternal aggression: Hormonal, genetic, and developmental determinants. In: Krasnegor NA, Bridges RS, editors. Mammalian parenting: biochemical, neurobiological, and behavioral determinants. New York: Oxford University Press. p 118–132. Svare B, Betteridge C, Katz D, Samuels O. 1981. Some situational and experiential determinants of maternal aggression in mice. Physiol Behav 26:253–258. Vasilieva NY, Sokolov VE. 1994. The role of midventral gland secretion in individual discrimination by Djungarian hamster (Phodopus campbelli Thomas, 1905) females. Horm Behav 98:192–200. Villalba C, Boyle PA, Caliguri EJ, De Vries GJ. 1997. Effects of the selective serotonin reuptake inhibitor fluoxetine on social behaviors in male and female prairie voles (Microtus ochrogaster). Horm Behav 32:184–191. Wise DA. 1974. Aggression in the female golden hamster: effects of reproductive state and social isolation. Horm Behav 5:235–250. Wise DA, Pryor TL. 1977. Effects of ergocornine and prolactin on aggression in the postpartum golden hamster. Horm Behav 8:30–39. Wolff JO. 1985. Maternal aggression as a deterrent to infanticide in Peromyscus leucopus and P. maniculatus. Anim Behav 33:117–123. Wolff JO. 1993. Why are female small mammals territorial. Oikos 68:364–370. Wynne-Edwards KE. 1998. Evolution of parental care in Phodopus - conflict between adaptations for survival and adaptations for rapid reproduction. Amer Zool 38:238–250. Wynne-Edwards KE, Lisk RD. 1987. Behavioral interactions differentiate Djungarian (Phodopus campbelli) hamsters and Siberian (Phodopus sungorus) hamsters. Can J Zool 65:2229–2235. 302 Gammie and Nelson

Bon je ne suis pas aussi douée pour faire de belles présentations mais je vais vous montrer également la honte que j'ai pour mon tit poussin Kunu. Sa cage Rody Duo avec roue minuscule, peu de litière, même si j'ai changé au rdc avec du lin, chanvre et copeaux (je sais c'est pas bien....). Voici donc quelques photos du premier logis qui n'est pas adapté mais j’apprends vite grâce à vous tous et Kunu sera très bientôt heureuse dans son terra. Et sa bin cage où elle joue quand je la sors. Comme certains ont pu le lire dans nouvel habitat pour Kunu, j'attendais avec impatience de recevoir son nouveau terra de 100x73x70 (h). MAJ : Photo du terra ! Et voici le nouveau terra de Kunu, juste après son arrivée difficile à la maison jeudi dernier. Photo souvenir avec mon chouchou et moi. Ca permet de voir la taille du terra, et nous aussi. On discute, on discute, mais comme ça vous voyez à qui vous parlez. Depuis, pas mal d'aménagements ont été fait, il est presque fini. Donc, sacré changement depuis la 1ère cage Rody Duo avec ses copeaux de bois, sa roue de 12 et toutes les bêtises des débutants.... Un terra de 100x73x68. Kunu s'habitue progressivement et à l'air de s'y plaire. Plus de photo ici : http://www.hamster-planet.com/t1667p140-nouvel-habitat-decide-pour-kunu-un-terra-de-100x73x50

sorry mais je me suis trompée sur le précédent... j'ai remis la même image... pas fait exprès.... et le ratelier à foin et le pont Je vais inclure tous ces accessoires dans son nouvel habitat, un terra que je devrais avoir d'ici une quizaine. Les objets ne sont pas chers, du style l'avion qui fait 32 cm de long a coûté 5€. La qualité n'est pas top en comparaison des photos d site mais bon, cela me semble être un bon rapport qualité prix. J'essaierais d'améliorer le tout, en ponçant et finissant ces articles pour qu'ils soient plus beaux.

et celui qui va lui plaire beaucoup je pense, la tour de jeux (terrier où elle peut creuser dans la litiere sur 20 cm).

Et voici son aire de jeux avec rampe d'escalade et echelees

Ensuite voici son avion !!! elle a l'âme voyageuse.... j'oubliais, pour le moulin, il est avec rdc, 1er et 2ème étage, que l'on peut demonter et on voit bien les echelles d'acces pour monter qui me paraissent bien.

Bon bein j'ai reçu enfin ma commande de Zoomalia... Pfffiouuuuu.... Il y a de la casse mais le sav gère de suite le blème. Je vous tiend au courant de la suite des évènements.... Mais en attendant, voici les photos des nouveaux joujoux de Kunu !!! et pour commencer, son moulin à vent (42cm de hut incluant les ailes). ?i=17&u=18171811][img]http://i70.servimg.com/u/f70/18/17/18/11/wp_00010.jpg[/img][/url]

Il cavale vite à la fin !!!! lol faut suivre... trop chou !!!

Il y a plein de choses qui ont été modifiées depuis le début de mon post sur mon projet, et qui tiennent compte de vos apports. Et je vous en remercie vivement. Les 20 cm de litière ont déjà été prévus, le rebord doit tenir compte de cela bien entendu. Je ne suis pas stupide... Et j'apprends de vous, notamment. J'ai agrandi le terra de 50 à 70 cm de haut, comme déjà écrit précédemment, ce qui permet d'avoir cette hauteur de litière suffisante sous les parois vitrées coulissantes qui seront réajustées pour permettre cela. L'aeration se situe horizontalement sous les vitres coulissantes, si tu regardes les modèles sur le site de Michel (verre superluxe), tu comprendras. Il est prévu également qu'au lieu que ce soit noir en dessous ces vitres coulissantes, il mettra une paroi en verre, et je dois voir avec lui pour trouver un système qui permette d'extraire 2 bacs amovibles en verre pour la litière (nettoyage simple et pratique). avec communication entre les 2 par un système d'ouverture (trous en hauteur). Les 2 grilles hautes d'aeration sont larges et amovibles pour pouvoir les retirer l'été justement quand il fera chaud. Et le fait de recouvrir le dos qui sera en fait ce decor avec plateformes, (pas nombreuses mais juste une grosse à gauche avec un tronc qui permettra de grimper dessus et 2 autres plateformes, une petite au mileu, et une autre grande à droite) et une partie du toit avec un vinyl de couleur foncée évitera à la chaleur de rentrer trop en comparaison avec un verre transparent qui fait loupe. Les roulettes du socle me permettront également de bouger le terra pour le mettre à un endroit plus frais dans l'appartement, ou sur le balcon à l'ombre (mais sans courant d'air).

suis désolée mais les photos des modèles de Michel ne passent pas....

Terra superluxe verre Michel (avant adaptations diverses et sur mesure) : modèle de base Pour un terra en verre super luxe de 100*73*50 finition 1675 (dessus arrière + 2 côtés hublot ) avec hauteur sous vitre coulissantes de 20 cm et verre au dessous au lieu d’une cloison opaque = 173€ + décor style 3 ( 1 grosse plateforme mi hauteur a gauche avec pour accès une grosse branche et le reste du décor relief et schiste = 150€ Ce n’est pas le modèle définitif puisque j’ai choisi ensuite, pour le bien de Kunu et des raisons personnelles pratiques liées à mon intérieur, des dimensions 100x73x70 (h) Qu’il y aura : deux grilles amovibles d’aération au lieu d’une sur le dessus (hautes), plus la grille d’aération sous les vitres coulissantes (basses), permettant une meilleure circulation de l’air, la déco (plateformes) sera sur 3 côtés (fond et les 2 hublots gauche et droite) au lieu d’un côté (fond) seulement, le toit en partie en verre transparent et une partie avec finition vinyle délimitée par les grilles d’aération (protection de la lumière) et d’autres finitions, aménagements, accessoires non encore définis et / ou validés que je verrais avec Michel vendredi et non plus jeudi. Le reste du prix indiqué (800€) correspondait à des options complémentaires, le meuble sur roulette (260€) que je supprime pour augmenter la hauteur du terra qui sera posé sur un socle en bois avec finitions peinture sur roulettes, d’autres accessoires (ex : tapis chauffant sous le terra avec réglage thermostat / on – off lorsque Kunu est malade ou lorsqu’elle se réveille et qu’elle tremble pour remonter sa température corporelle ; éclairage rouge ; etc), protections, le transport effectué par Michel qui me compte très logiquement ses frais d’essence et de péage plus son temps (145€ pour Belgique – Paris). Il s’agit d’un jeune artisan belge installé à son compte et non d’une société allemande qui travaille avec e-bay. La comparaison est difficile avec le terra « idéal » conseillé par Shechou (sujet nouvel habitat pour mes 2 hamsters) qui est très très bien lui aussi. Il s’agit d’un terra bois tandis que je parle d’un terra verre, et son modèle est brut, sans aménagement et qu’il faut effectivement prévoir les finitions de vernissage. Je pense tout de même que les tarifs de Shechou sont quand même moins chers que ceux de Michel, à priori 50% de moins si on compare ses terra bois avec le modèle qu’elle indique. Tout cela est positif, nous avons 2 fournisseurs de terra différents qui peuvent adapter leurs modèles existants pour les hamsters. Car je tiens à insister qu’en l’état, ils ne sont pas fait ou pas adaptés exactement aux hamsters ! La hauteur sous votre coulissante doit être relevée pour pouvoir mettre une grande hauteur de litière (minimum 20 cm), et le verre semble plus adapté que le bois qui peut être rongé à la longue, s’imbiber des odeurs d’urine et moins facilement « lavable » que le verre. C’est bien ce que je disais, les solutions trouvées sur le forum sont géniales et montrent l’ingéniosité de ses membres mais correspondent à un esprit débrouillard face à des lacunes évidentes des offres sur le marché. Le modèle de Shechou est un modèle pour des reptiles, tortues et non pas destiné spécifiquement au hamster, même s’il se rapproche de l’idéal, est certainement le produit le plus adapté aujourd’hui, sans pour autant lui être dédié et peut être amélioré, en créant un modèle qui serait distribué sur le marché et donc dont le prix serait moindre du fait de la production en série.

En fait, j'ai cru comprendre que l'augmentation de l'agressivité était liée avec la baisse de la testosterone et pas l'augmentation. Quelqu'un peut il confirmer ou infirmer ? Et il s'agit d'une étude sur les hamsters russes qui ont la particularité de "vivre" des changements physiologiques, comportementaux pendant la période hivernale (liée à l'exposition nuit / jour où les jours sont plus courts) et pas sur les autres hamsters, mais cela ne veut pas pour autant dire que ceux ci ne sont pas concernés car pour l'instant, je n'ai pas trouvé d'étude dans ce sens. Par contre, je ne sais plus où j'ai vu ça, mais la période où les hamsters sont les plus calmes, dans ue sorte de "torpeur", d'activité ralentie, c'est en février - mars, et on est en plein dedans en ce moent. J'ai pu le constater sur Kunu. Dites nous si c'est pareil pour vous.

Yes ! C'est ce que j'essaie de trouver Mio, c'est pas simple... Mais on s'accroche !!! Et je mettrais en ligne quand j'en aurais d'autres. Gros poutous à vous tous...