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The influence of bedding depth on behaviour in golden hamsters (Mesocricetus auratus)
Abstract
Although digging was found to be important in captive rodents, most golden hamsters are provided with only little material to dig. In this study, the influence of different bedding depths and acute stressors on the behaviour and welfare of golden hamsters was analysed. Forty-five male golden hamsters were assigned singly to three experimental groups with 80, 40 or 10 cm deep wood shavings. Behaviour was evaluated by continuous running wheel activity and video recordings, a series of stressors was applied after 7 and 8 weeks. Burrows, if constructed, were mapped monthly. Additionally, adrenals, testes and body mass as well as hormone levels of corticosteroids and testosterone were measured at euthanasia. Hamsters kept with 10 cm deep bedding showed significantly more wire-gnawing and a higher running wheel activity than the hamsters in the other groups. In 80 cm deep bedding wire-gnawing was never observed. Stressor application showed no significant immediate influence on behaviour. All hamsters in 40 and 80 cm bedding constructed burrows which they occupied. The body condition (body weight/body size(3)) was significantly higher in the animals kept in deep (80 cm) compared with those housed in low (10 cm) bedding cages. The relative testes weights were significantly heaviest in the medium treatment group. No significant differences could be detected for the adrenal glands and testosterone levels. In this study, we showed that cages with at least 40 cm of bedding seemed to enhance the welfare of golden hamsters, although those in 80 cm bedding had more body fat compared with the other groups. However, deep bedding which is appropriate for burrowing can be recommended for golden hamsters. (c) 2005 Elsevier B.V All rights reserved.
... Previous research has detailed the importance of improved housing and husbandry for better welfare, including for hamsters in a laboratory setting. [5][6][7][8][9] Moreover, the five domains model for animal welfare assessment highlights the importance of the 'physical environment' (domain 2) and 'behaviour' (domain 4) to animal welfare. 10 experiences that may arise from inhabiting a particular environment and being able or unable to express particular behaviours. ...
... Syrian hamsters are solitary animals and should be housed alone, 6,12,14 and most respondents followed this recommendation and reported housing their hamster alone. The hamsters were provided with a wide range of enrichment items in the cage, which typically included some sort of shelter (vital for prey species 6,10,12-14 ), a chew toy (vital for preventing dental disease, including overgrowth or misalignment of incisors 12 ) and an area for digging Teeth Chattering Frequency F I G U R E 5 Boxplots of the frequency scores for the owner-reported frequency of teeth chattering; the possible scores range from 0 (never) to 10 (several times per day), split by the cleaning frequency (vital for burrowing animals 6,9,12,14 ). Additionally, the majority of hamsters had access to a wheel, which is good given that hamsters will choose to run on wheels even in enriched cages. ...
... Most owners reported using paper bedding in their hamster's cage; this bedding is considered safe and appropriate for construction of burrows. 6,9,12,18 Scatter feeding was the most popular way of feeding. This enables the hamsters to show natural foraging and hoarding behaviours, 6 which has been shown to be an important behaviour in the wild. ...
Background:
Syrian hamsters are a relatively common pet species in the UK. However, we know very little about how they are kept. The aim of this study was to identify areas of good and poor practices among Syrian hamster owners using owner surveys.
Method:
A survey of pet hamster owners was conducted with questions on husbandry, behaviour and health.
Results:
There were 548 survey responses. Over 95% of the owners provided a wheel, hideaway or chew toy, and over 90% housed their hamster alone. However, 18.4% of the owners used hamster balls, hamsters may have been fed a diet that was not entirely appropriate, and over 45% of respondents reported that their hamsters were housed in close proximity to predator species. Most (65.9%) hamsters had never been taken to a veterinarian. Hamster ball use, shallower substrate depth and more frequent handling were significantly associated with greater owner observations of bar biting.
Limitations:
A key limitation is that the respondents may not be representative of the average pet hamster owner, so this research does not provide a complete picture of the current state of hamster welfare.
Conclusion:
There are some welfare concerns regarding the way Syrian hamsters are currently kept in the UK. Therefore, attempts to better distribute information about hamster care to owners should be made.
... However, WR varies with circumstance, increasing as current environmental quality declines. It is thus higher in barren cages than enriched ones [12][13][14][15][16]; and in animals exposed to noise, rough handling, intra-specific aggression or predator cues [12,14,[17][18][19][20], or deprived of food [8,21], mates [18] or alcohol (if addicted [22]). When elicited by sub-optimal circumstances like these, WR may represent thwarted, unsuccessful, and thence maladaptive attempts to relocate [18]. ...
... However, WR varies with circumstance, increasing as current environmental quality declines. It is thus higher in barren cages than enriched ones [12][13][14][15][16]; and in animals exposed to noise, rough handling, intra-specific aggression or predator cues [12,14,[17][18][19][20], or deprived of food [8,21], mates [18] or alcohol (if addicted [22]). When elicited by sub-optimal circumstances like these, WR may represent thwarted, unsuccessful, and thence maladaptive attempts to relocate [18]. ...
... When elicited by sub-optimal circumstances like these, WR may represent thwarted, unsuccessful, and thence maladaptive attempts to relocate [18]. Consistent with this, WR is also highest in environments eliciting the most bar-mouthing in hamsters [14], and can be reduced with anxiolytics [7]. ...
... In a previous study, deep bedding enabling golden hamsters to build burrows was shown to improve welfare in golden hamsters because they did not display stereotypic wire-gnawing (Hauzenberger et al. 2006). A preference for litter and bedding material was shown earlier (Arnold and Estep 1994). ...
... Particularly, if an animal regularly engages in activities other than wheel running it might be preferable to have additional measurements. The use of infrared motion detectors (DeCoursey 1986;Pratt and Goldman 1986), in-cage movement recordings (PhenoTyper 1 ; de Visser et al. 2005), telemetry for body temperature and locomotion (Boulos et al. 1996), and video recordings (Gebhardt-Henrich et al. 2005;Hauzenberger et al. 2006) have been described. ...
... Males were chosen because their daily running wheel activity was shown to be more stable than in females (Gattermann et al. 1985;Vonlanthen 2003) and male hamsters have been shown to be more active (Gattermann et al. 1985). They engage in nest-building if given the opportunity (Hauzenberger et al. 2006), even more frequently than females (Guerra and Ades 2002). ...
In a previous study, golden hamsters living in self-constructed burrows showed reduced running wheel activity and decreased activity outside the burrows compared with animals without the possibility to dig burrows. Since different activity apportionments might account for that, different activity measurements were performed to show the relationship of different parts of general activity: running-wheel activity, activity inside and activity outside the bedding. Twelve hamsters in low bedding (<10 cm) were compared with 12 hamsters in deep bedding (80 cm). To further test the synchronisation to the light system, the animals were observed under light–dark (L:D) and under constant dark (D:D) conditions. Hamsters in deep bedding were significantly less synchronised to the light system, developed longer circadian rhythms tau (τ), had later activity onsets in the running wheel and a lower running wheel activity than hamsters in low bedding cages. Their activity onsets inside the bedding were later. Time differences between the onset of movements inside the bedding and the onset of running wheel activity were not significant. Thus, the later appearance of golden hamsters kept in deep bedding was not fully compensated by more activity inside the burrows.
... In mice and gerbils, wire-gnawing is commonly interpreted as an indication of suboptimal housing conditions [8][9][10] . Golden hamsters devote a large proportion of their active time to wire-gnawing when kept in cages with litter less than 10 cm deep, but do not wire-gnaw in cages with 80-cm-deep litter 11 . Therefore, deep litter seems to improve the welfare of captive golden hamsters. ...
... It is not known whether handling and other laboratory practices-like induction of anesthesia-are more stressful for these animals. It is possible that housing hamsters in deep litter decreases chronic stress levels 11 but also increases the hamsters' susceptibility to acute stress. Although unintended negative consequences of environmental enrichment are rare, such reports are not unknown 12 . ...
... We filmed the hamsters as previously described 11 . Thirteen weeks after weaning, we decapitated the hamsters after isoflurane-anesthesia (5%) between 8:30 and 10:00 a.m. ...
Deep litter has been shown to decrease stereotypic wire-gnawing in male golden hamsters, suggesting that increased litter depth may be associated with decreased chronic stress levels. To determine the relationship between litter depth and stress levels in hamsters, the authors measured serum levels of corticosterone, cortisol, and ACTH in male golden hamsters kept in cages with three different depths of litter. The duration of handling the hamsters significantly increased the concentrations of corticosterone, cortisol, and the ratio of cortisol/corticosterone. It took longer to catch hamsters housed in cages with deep litter and the ACTH levels were higher in these hamsters. The positive effect of the enrichment (deep litter) was diminished by methodological problems during handling/anesthesia.
... 30 In golden hamsters, a substrate depth of at least 40 cm (15.8 in) appears to improve their welfare, but depths of 80 cm (31.5 in) cause significant increase in body fat. 87 In the same study, when kept in low bedding (10 cm or 3.9 in), approximately 50% of the hamsters developed wire-gnawing behavior. 87 Shredding or cutting paper towels or newspaper into strips is an inexpensive and practical source of deep substrate. ...
... 87 In the same study, when kept in low bedding (10 cm or 3.9 in), approximately 50% of the hamsters developed wire-gnawing behavior. 87 Shredding or cutting paper towels or newspaper into strips is an inexpensive and practical source of deep substrate. There are anecdotal reports of possible toxicity from newspaper ink, but, to our knowledge, no scientific proof of this is available for rodents. ...
Although rodents have been in captivity for centuries, they still express many of their natural behaviors. As their popularity in the pet trade increases, it becomes important to address their welfare, including the avoidance of abnormal and detrimental behaviors. Inappropriate husbandry practices may lead to psychological and physical disorders. The extensive amount of information available, as well as the large number of rodent species maintained as pets, makes it difficult to apply a broad set of behavior rules for rodents. Nonetheless, there are basic behavior models that should be considered for all rodent species. This article presents basic concepts of behavior of rodents with enclosure and nutritional enrichment techniques that can be used to support a fulfilling and interactive life. Copyright 2011 Elsevier Inc. All rights reserved.
... Tak hanya itu, mereka juga menggunakan kandang jeruji kecil yang tidak sesuai bagi hamster. Hamster butuh luas kandang minimum 10,000 cm 2 dengan alas kandang yang cukup tinggi (Fischer et al., 2007;Hauzenberger et al., 2006). Jika kebutuhan tersebut tidak terpenuhi, hamster bisa stress akut yang dapat berujung pada kematian. ...
Little Milku adalah sebuah media edukasi yang membahas seputar perawatan hamster yang benar karena salah kaprah perawatan hamster masih merajalela di Indonesia. Little Milku baru saja dibentuk pada awal tahun 2022 sehingga awareness terhadap brand masih rendah karena masih belum adanya konten yang diunggah untuk menarik audiens. Penelitian ini bertujuan untuk mengetahui bagaimana perancangan konten yang efektif digunakan sebagai media edukasi perawatan hamster. Media sosial instagram terpilih sebagai media utama untuk menjangkau target audiens Little Milku yang merupakan remaja perempuan Gen Z dengan usia 18-24 tahun karena fitur utamanya yang memanfaatkan konten berupa foto dan video. Penelitian ini menggunakan metode pengumpulan data sekunder melalui studi literatur dari buku dan jurnal yang membahas mengenai promotional media, social media marketing, kartun dan komik. Data juga didapat dari metode pengumpulan primer secara kualitatif melalui hasil wawancara terhadap expert user di bidang ilustrasi dan extreme user yang merupakan followers Little Milku. Selain itu, data juga didapat secara kuantitatif melalui survei kepada 155 followers Instagram Little Milku. Dari penelitian tersebut didapatkan hasil bahwa untuk membuat konten yang bisa secara optimal digunakan sebagai media edukasi maka diperlukan bantuan ilustrasi dengan gaya visual kartun dengan warna yang sesuai dengan selera target audiens untuk memfokuskan atensi target audiens. Konten yang dibuat juga harus memiliki value yang selaras dengan tujuan utama Little Milku yaitu menjadi media edukasi perawatan hamster yang menarik. Kata Kunci: Konten, Instagram, Edukasi, Perawatan Hamster
... Stereotypic bar-mouthing or gnawing of the wire bars or lid of the cage is an observed abnormal behavior in hamsters (Arnold and Estep, 1994;Hauzenberger et al., 2006). The provision of running wheels, at least in one study, decreased this behavior (Gebhardt-Henrich et al., 2005). ...
... In a study of golden hamsters, animals were provided with either 10, 40, or 80 cm of wood shaving bedding. The animals with 10 cm of bedding exhibited more wheel activity and wire-gnawing behavior suggesting increased anxiety [56]. Mice housed in shallow bedding displayed more nest building activity than mice in deeper bedding conditions. ...
Rodent models of brain disorders including neurodevelopmental, neuropsychiatric, and neurodegenerative diseases are essential for increasing our understanding of underlying pathology and for preclinical testing of potential treatments. Some of the most important outcome measures in such studies are behavioral. Unfortunately, reports from different labs are often conflicting, and preclinical studies in rodent models are not often corroborated in human trials. There are many well-established tests for assessing various behavioral readouts, but subtle aspects can influence measurements. Features such as housing conditions, conditions of testing, and the sex and strain of the animals can all have effects on tests of behavior. In the conduct of behavior testing, it is important to keep these features in mind to ensure the reliability and reproducibility of results. In this review, we highlight factors that we and others have encountered that can influence behavioral measures. Our goal is to increase awareness of factors that can affect behavior in rodents and to emphasize the need for detailed reporting of methods.
... The results are consistent with previous studies that have shown the importance of adequate cage bedding for thermoregulation 16,25 and for species-appropriate husbandry 3,18 . A positive effect npg of deeper cage bedding on the welfare of rodents other than mice has been reported; for example, golden hamsters housed in cages with 80 cm of bedding engaged in significantly less wire-gnawing behavior than those housed in cages with 10 cm of bedding 30 . ...
In order to improve the welfare of laboratory mice, a number of different environmental enrichment strategies have been developed to provide opportunities for mice to engage in naturalistic behaviors. Providing sufficient cage bedding for mice to use as a burrowing substrate could be considered an environmental enrichment strategy, but few studies have considered the welfare aspects of cage bedding amount. The authors compared the preferences of group-housed female BALB/c and C57BL/6 mice for three different volumes of cage bedding (0.5 l, 1.5 l and 6 l). Mice of both strains but especially C57BL/6 mice showed strong preferences for cages with more bedding. The results highlight the importance of providing a sufficient amount of cage bedding to laboratory mice.
... In Canada for example (Canadian Council on Animal Care, 2010), 5724 hamsters were used for research purposes in 2008, making them the fourth most used rodents after mice (1,053,946), rats (305,819) and guinea pigs (28,810). So far, hamster welfare has been studied in terms of their social housing (Arnold and Estep, 1990), nest boxes (Ottoni and Ades, 1991), cage floor preference (Arnold and Estep, 1994;Arnold and Gillapsy, 1994), cage dimensions (Kuhnen, 1999;Fischer et al., 2007), environmental enrichment (Reebs and Maillet, 2003), running wheels (Mrosovsky et al., 1998;Gebhardt-Henrich et al., 2005;Reebs and St-Onge, 2005), and bedding material (Hauzenberger et al., 2006;Lanteigne and Reebs, 2006). Many aspects of hamster welfare, however, remain open to study. ...
This study tested whether Syrian hamsters (Mesocricetus auratus) have an aversion to old bedding (up to 14 days) by offering them the option to nest in a new cage. A secondary goal was to assess the relative value of shelters by testing whether the tendency to nest in the new cage was reduced when a shelter was present in the old cage. Individual hamsters were placed in two cages connected by a tunnel, and left to familiarize themselves with this set-up for 10 days. Then the bedding was changed in each cage, and for the next 3, 9, or 14 days the tunnel was blocked and each hamster lived in only one of the cages, either with or without a shelter (PVC pipe) present in that cage. Then the tunnel was unblocked and for the next 3 days the position of each hamster's nest in either of the two cages was noted. After 3, 9, and 14 days in the old cage, respectively 10, 11, and 8 out of 15 males and 6, 9, and 3 out of 15 females never nested in the new cage, whether the old cage had a shelter or not. Only 2, 1, and 4 out of 15 males, and only 5, 3, and 5 out of 15 females nested in the new cage more than in the old one in the absence of shelters. Of those males that nested in the new cage at least once, three out of five, three out of four, and five out of seven nested in the new cage less often when a shelter was present in the old cage than when no shelter was present. For females, the corresponding numbers were 8 out of 9, 5 out of 6, and 11 out of 12. These results indicate that access to a new (though still familiar) cage with fresh bedding holds only a small attraction for nesting hamsters, at least when their current bedding is up to 14 days old, and that shelters are valued.
... Among the aspects of hamster welfare that have been studied so far are social housing, 2 nest boxes, 3 cage floor preference, 4,5 cage dimension, 6,7 environmental enrichment, 8 running wheels, 9 -11 and bedding material. 12, 13 Kuhnen 14 and Sørensen et al. 15 provide reviews of housing requirements for hamsters, and Gattermann et al. 16 gives information on the poorly known ecology of this species in the wild. ...
The present study investigated the effects of bedding material (pine shavings versus beta chip) and running wheel surfaces (standard metal bars versus metal bars covered with a plastic mesh) on the occurrence of wounds on the paws of male and female Syrian (golden) hamsters, Mesocricetus auratus. Four groups of 10 males and 10 females were each assigned to one of the following treatments: pine/no mesh, pine/mesh, chips/no mesh and chips/mesh. Each hamster paw was observed at 1-3-day intervals for 60 days. A total of 1-3 wounds, separate in time, developed on the paws (mostly the hind ones) of almost all animals. Wounds appeared as small pinpricks, cuts or scabs, mostly on the palms. Females ran 15% less than males, yet their front paws were more commonly affected and their wounds tended to last longer. Hamsters with plastic mesh inside their wheels took longer to develop wounds but once they appeared, the wounds were larger and lasted longer. Hamsters on pine shavings developed fewer wounds and had more wound-free days. Hamsters kept running at high levels and many wounds did not heal during the study, suggesting a need for veterinary intervention.
Common medical problems diagnosed and treated in individual companion exotic mammals are relevant in a herd-health setting. Many of these problems are often associated with poor husbandry and/or inappropriate nutrition. Rabbits, ferrets, chinchillas, and rodents have been domesticated alongside humans and an understanding of their ethology gives veterinarians a base knowledge in making recommendations for animals in their care. This article briefly reviews the ethology and husbandry in such species, but detailed needs are beyond the scope of this article.
Hamsters are one of the commonly used animal species in research related to virology and infectious agents. Hamsters are similar to human beings in many metabolic and physiological processes. Though the use of hamsters in research has declined in the last few decades, the genetically engineered Syrian hamster (GESH) model is seeing increased popularity due to advancements in gene-editing technologies like CRISPR/Cas9. The presence of immunologically privileged large highly distensible non-glandular cheek pouches makes hamsters a preferred model for oral carcinogenesis, microvascular investigations of inflammation, ischemia-reperfusion investigations, tumor development, and vascular smooth muscle function. Due to the unique immune system of hamsters, skin allografts are not rejected to the degree as compared to other models and have a higher susceptibility to certain infections. It is already known that for, cell culture experiments, Chinese hamster ovary (CHO) cells are extensively used. This chapter will briefly discuss general anatomy, physiology, husbandry, and reproduction, followed by references to reported research uses.
Hamsters are popular pets in the UK. The Syrian or Golden hamster (Mesocricetus auratus) is the best known species in the pet trade, with a variety of dwarf species also encountered. Gastrointestinal disease occurs frequently, and diarrhoea is a common presenting complaint. This is most often associated with bacterial or parasitic infection, but can also be related to neoplasia or the use of certain antibiotics. Initial stabilisation of the hamster with diarrhoea should include provision of a warm stress-free environment, fluid therapy, nutritional support with an appropriate critical care diet and analgesia. Following a full history and clinical examination, further diagnostic steps include faecal parasitology and microbiology, routine biochemistry and haematology, radiography with or without positive contrast, and abdominal ultrasound. Indications for surgery include evidence of intestinal obstruction or prolapsed intussusception. This article gives an overview of the most common gastrointestinal diseases encountered in hamster species and provides a guide of how to logically approach the investigation and treatment of these cases, achievable in general practice.
Hamsters are commonly kept as children's pets and although there are approximately 24 different species, only five are established pets. Of these the Syrian or golden hamster (Mesocricetus auratus) and dwarf hamsters (Phodopus sungorus, Phodopus campbelli and Phodopus roborowskii) are popular whereas the Chinese hamster (Cricetulus griseus) is less frequently kept. Hamsters are spontaneous ovulators, with a defined breeding season. They respond to photoperiod, with long days inducing reproductive activity in wild individuals and breeding occurring in Spring and Summer. This chapter discusses the clinical evaluation, basic techniques, common medical and surgical conditions, preventative health measures, and radiographic imaging for the hamsters. The clinical evaluation includes history‐taking, handling, sex determination, and clinical examination. The basic techniques include sample collection, nutritional support, fluid therapy, anaesthesia, euthanasia, and hospitalisation requirements.
The hamster species used as research models include the Syrian (golden), Mesocricetus auratus; the Chinese (striped-back), Cricetulus griseus; the Armenian (gray), C. migratorius; the European, Cricetus cricetus; and the Djungarian, Phodopus campbelli (Russian dwarf) and P. sungorus (Siberian dwarf). Hamsters are classified as members of the order Rodentia, suborder Myomorpha, superfamily Muroidea and in family Cricetidae. Animals in this family are characterized by large cheek pouches, thick bodies, short tails, and an excess of loose skin. They have incisors that erupt continuously and cuspidate molars that do not continue to grow ((I 1/1, C 0/0, PM 0/0, M 3/3) × 2 = 16). In 2010, it was reported that approximately 146,000 hamsters were used in research in the United States (United States Department of Agriculture, 2010).
The study of laboratory animal behavior has increased steadily over the last decade, with expanding emphasis on a variety of commonly used species. In the United States, this trend was initially focused on species for which there was a regulatory requirement to consider normalizing behavior, specifically the U.S. Department of Agriculture's requirement to promote the psychological well-being of nonhuman primates as reflected in the 1991 Animal Welfare Regulations (AWRs). With the advent of the seventh edition of the Guide (NRC, 1996), more emphasis was placed on addressing the structural, social, and activity elements in all laboratory animals' cage or pen environments in what was referred to as a 'behavioral management program.' The implication that environmental enrichment is a de facto means of normalizing laboratory animal behavior is evidenced by the discussion of this topic as one component of the microenvironment (i.e., cage) for all laboratory species in the eighth edition of the Guide (NRC, 2011). The 2011 Guide also devoted an entire section to 'Behavioral and Social Management,' highlighting the importance of motor, cognitive, and social activity; the social environment, noting that single housing of social species should be the exception; and procedural habituation and training of animals.
This chapter provides a review of the management, husbandry, and colony health requirements of the Syrian or golden hamster, Mesocricetus auratus, used in biomedical research. Hamsters are rodents belonging within the family Crecetidae. Members of the Crecetidae family are characterized by large cheek pouches, relatively thick bodies, and a short tail. Hamsters are generally housed in cages that are appropriate for housing other laboratory rodents. Contemporary cages are generally made of commercially manufactured rigid plastic materials (i.e., polycarbonate, polysulfone, and polypropylene) or stainless steel. The chapter studies the environmental conditions required for a Syrian hamster, which include the ventilation, illumination, temperature, and humidity conditions. Hamsters are generally provided commercially produced pelleted rodent diet intended for mice and rats, and animals raised on such diets show normal growth and reproduction. The chapter studies the breeding and record keeping of hamsters. Sexual maturity in the hamster generally occurs at approximately 6 weeks (42 days) of age, although copulatory activity can begin as early as 4 weeks of age. Health records, also referred to as clinical records, can be maintained as group records for large populations, such as commercial breeding colonies, or as individual animal records. Health records should include pertinent clinical observations and diagnostic information, history of surgical procedures, postoperative care, and information on experimental use, as it pertains to clinical care of the animal.
In order to determine a stress response, two groups of twenty male golden hamsters were either exposed to a ferret or handled by a human. The hamsters’ body temperature and running wheel activity were measured as stress correlates. Half of the hamsters’ cages were equipped with a functional running wheel to determine whether the presence of a running wheel might reduce stress. Exposure to the ferret was followed by a significant increase in body temperature and running wheel revolutions; however, running wheel activity did not change after handling. Body temperature increased less after handling in hamsters living in a cage with a functional running wheel than in those with a non-revolving running wheel. This suggests that hamsters with a functional running wheel reacted less strongly to acute stress caused by handling. On the other hand, temperature increase after the exposure to a ferret was not affected by the presence of a running wheel. Both exposure to a ferret and handling caused stress in golden hamsters, as demonstrated by an increase in body temperature (emotional fever). Stress caused by handling was much milder than stress caused by the ferret.
In the wild, golden hamsters live in deep burrow systems, and hidings like shelters or burrows should also be available to animals in captivity. The aim of the present paper was to investigate putative effects on the circadian activity rhythm of golden hamsters with bedding material as enrichment. Three different bedding depths (10 cm, 40 cm, 80 cm) were investigated in 45 males (15 per group) kept singly. Their wheel-running activity was recorded continuosly. The light–dark cycle was 12:12 h with 30-min dusk and dawn periods. Activity onsets coincided well with lights-off in low bedding depth, but in the groups with 40 and 80 cm the activity rhythms did free run with a significant increase in tau with bedding depth. All hamsters in medium and deep bedding built and lived in self-constructed burrows. It is possible the difference in light intensity between light (50–85 lux) and dark conditions (0.5–2 lux) might have been too low. As a consequence the LD zeitgeber was not strong enough to entrain the activity rhythms, though the light was bright enough to stop running at least in some animals (masking). Hamsters of the low bedding group were continuously exposed to the light–dark cycle and thus were able to synchronise their activity rhythm. We conclude that bedding depth can influence the circadian rhythm of golden hamsters which has to be taken into account when performing chronobiological studies.
Many sources of variation in animal experiments are related to characteristics of the animal or its husbandry conditions. In ethologic studies, observational methods can also affect interexperimental variation. Different descriptions for a behavior can lead to divergent findings that may be incorrectly attributed to other factors if not recognized as stemming from a classification dissonance. Here we discuss 2 observational studies in Mongolian gerbils (Meriones unguiculatus). The first study describes how data vary when 2 different working definitions are used for stereotypic digging: WD(mor), a definition based on a morphologic description of the behavior, and WD(12), a definition that relies mainly on a duration criterion of digging bouts (greater than 12 s). The total duration and number of stereotypic bouts were 22.0% and 63.1% lower, respectively, when WD(12) was applied compared with WD(mor). However, strong correlations existed between data generated by WD(mor) and WD(12), indicating that the 2 definitions yielded qualitatively similar results. The second study provides the first report that laboratory gerbils develop stereotypic behavior that is characterized by alternating bouts of digging and bar-gnawing. Of the 1685 stereotypy bouts investigated, 9.1% comprised both stereotypies, 87.6% consisted of digging only, and 3.3% consisted of bar gnawing only. Working definitions that neglect combined stereotypies can result in considerable underestimation of stereotypic behavior in Mongolian gerbils.
Consideration of the human-animal bond typically focuses on the benefits of companion animals to human health and well-being, but it is essential that in realizing these benefits the welfare needs of the animals, both physical and mental, are also met. Positive emotional relationships with animals are likely to increase recognition of animal sentience and so help create positive attitudes toward animals at the societal level, but, at the individual level, the animals to which humans are bonded should also benefit from the human-animal relationship. A strong human-animal bond may benefit animal welfare (e.g., by motivating an owner to commit time and funds to necessary veterinary medical treatment), but may also be the source of compromised welfare. Highly bonded owners may, for example, be reluctant to permit euthanasia on humane grounds, and the anthropomorphic nature of many human-companion animal bonds can contribute to the development of problem behaviors and obesity. The challenge for the veterinary profession is to ensure that widespread positive sentiment toward animals, which the human-animal bond generates, is translated in to human behavior and actions that are conducive to good animal welfare. This, it is suggested, can be achieved through adequate veterinary education in veterinary and animal welfare science, ethics, and communication.
Investigated the effects of cage size and cage surface texture as factors in environmental enrichment. 79 C57BL/6J mice were reared in 1 of 4 types of cages: small wire, small Plexiglas, large wire, or large Plexiglas. Dependent measures included gross body weight at 38 and 50 days of age, open-field activity and defecation, running-wheel activity, exploration, and water consumption. Cage size significantly affected 38-day gross body weight, open-field activity and defecation, and water consumption. These findings indicate that cage size is an important factor in the enriched environment experience, and they are in accordance with data reported previously by the authors. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Two expeditions were carried out during September 1997 and March 1999 to confirm the current existence of Mesocricetus auratus in northern Syria. Six females and seven males were caught at different sites near Aleppo. One female was pregnant and gave birth to six pups. Altogether, 30 burrows were mapped and the structures of 23 golden hamster burrows investigated. None of the inhabited burrows contained more than one adult. Burrow depths ranged from 36 to 106 cm (mean 65 cm). Their structure was simple, consisting of a single vertical entrance (gravity pipe) that proceeded to a nesting chamber and at least one additional food chamber. The mean length of the entire gallery system measured 200 cm and could extend up to 900 cm. Most burrows were found on agricultural fields preferentially on leguminous cultures. The distribution of golden hamsters is discussed in association with historical data, soil types, geography, climate and human activities. All 19 golden hamsters were transferred to Germany and, together with three wild individuals supplied by the University of Aleppo, form a new breeding stock.
To evaluate how and when mice run on a running wheel and how ad libitum access to the wheel affect behavior, feed intake, and weight gain.
Seventeen 2-month-old C57BL/6J mice had access to the wheel, whereas 19 control mice did not. After 3 to 6.5 weeks, behavior was video-recorded over 24 h for each mouse.
Experimental mice ran an average 2 km/24 h in 114 min. Highest running activity took place at the onset of darkness. Experimental mice spent 22 min more feeding on the cage floor than did control mice. These times were deducted from those for all other behaviors: 74 min from resting time, 39 min from climbing and feeding on the cage lid, 14 min from locomotion on the cage floor, and 10 min from grooming. In relative figures, deduction from sleeping time was only 9%, whereas climbing time was halved.
Climbing on the cage lid has a similar circadian rhythm as does wheel running and high-energy expenditure. Because experimental mice climbed less, their weight gain and feed intake were similar to those of control mice. Thus, wheel running can substitute for other forms of energy-consuming behaviors and vice versa.
All laboratory golden hamsters originate from a sibling pairing back in 1930. To investigate possible differences between domesticated and wild conspecifics, descendants of both strains were maintained under standardized laboratory conditions individually and in unisexual groups. Body mass and food consumption were monitored from birth to 22 weeks of age. The animals were subsequently sacrificed, and body measurements and body composition were analysed. In addition, the absolute and relative masses of different organs were measured. Laboratory hamsters gained more body mass through higher food consumption. However, they did not get fatter, since relative fat values were the same for both strains. Body measurements revealed only minor differences (in body and ear lengths). As deducible from the body mass, the organs (spleen, kidneys, adrenal glands, testes, epididymis and ovaries) were seen to be heavier in laboratory hamsters. Furthermore, with the exception of the kidneys, the same went for the relative values. There were distinct sexual specific differences in both strains only for body fat ( male symbol male symbol upward arrow ) and adrenal glands ( male symbol male symbol upward arrow ). In females, group housing induced an elevated level of aggression. In general, these housing conditions led to social stress symptoms, such as heavier adrenal glands. Additionally, spleen, kidneys, ovaries, body length and mass, body water and body fat were increased in group-housed hamsters. In conclusion, no major differences between laboratory and wild-derived hamsters were observed.
Institutional animal care committees may one day require for the welfare of captive hamsters more floor space and the introduction of tunnels and toys. As hamsters are popular animal subjects in chronobiological research, and as clock phase is usually measured through running wheel activity, it is important to determine what effect cage enrichment might have on daily wheel use. Here the daily number of wheel revolutions, the daily duration of the running activity phase, the phase relationship between lights-off and onset of running activity, and the free-running period of circadian activity rhythms were measured in Syrian hamsters, Mesocricetus auratus, housed in single cages or in multiple cages linked by tunnels and supplied with commercial wooden toys. Free-running periodicity was not affected by cage enrichment. In multiple-cage systems, there were fewer daily revolutions, shorter wheel-running activity phases, and delayed running activity onsets. These effects, however, were small as compared to interindividual and week-to-week variation. They were statistically significant only under a light:dark cycle, not in constant darkness, and only when interindividual variation was eliminated through a paired design or when the number of cages was increased to five (the maximum tested). Daily wheel use is thus affected by cage enrichment, but only slightly.
Some species - ring-tailed lemurs and snow leopards, for example - apparently thrive in captivity, whereas others, such as Asian elephants and polar bears, are prone to problems that include poor health, repetitive stereotypic behaviour and breeding difficulties. Here we investigate this previously unexplained variation in captive animals' welfare by focusing on caged carnivores, and show that it stems from constraints imposed on the natural behaviour of susceptible animals, with wide-ranging lifestyles in the wild predicting stereotypy and the extent of infant mortality in captivity. Our findings indicate that the keeping of naturally wide-ranging carnivores should be either fundamentally improved or phased out.
The cage systems commonly used for housing laboratory rats often result in sedentary and overweight animals, as a consequence of restricted opportunities for physical activity combined with ad libitum feeding. This can have implications both for animal well-being and for the experimental outcome. Physical activity has several known positive effects on health and lifespan, and physical fitness might therefore be incorporated into the animal welfare concept. The aim of this study was to investigate if and how pen housing affects the physical activity and fitness of rats. Thirty-two juvenile male Sprague-Dawley rats were randomly assigned to two different housing systems for a 4-week period. Sixteen rats were kept individually in standard Makrolon type III cages (42x26x18 cm) furnished with black plastic tubes (singly-housed, SI). The remaining rats were kept in groups of eight, housed in large floor pens (150x210 cm), which were furnished with various objects to increase environmental complexity (pen-housed, PH). The body weight gain, and food and water intake of the rats were measured. During weeks 3 or 4, home cage behaviour, urinary cortiosterone/creatinine ratios (CO/CR), and muscle strength on an inclined plane, were measured. Enzyme activities and glycogen content were measured in tissue samples from m. triceps brachii taken after euthanization at the end of the study. There were no significant differences between groups for food and water intake, but PH rats weighed 14% less than SI rats after 4 weeks, and PH rats also had a more diverse behavioural pattern than SI rats. PH rats had significantly higher oxidative capacity (28% more citrate synthase (CS)) and greater glycogen content (28%) in their muscle samples than SI rats. The PH rats performed significantly better on the inclined plane, both in the muscle strength test (mean angle 75+/-0.5 degrees for PH rats and 69+/-0.4 degrees for SI rats) and the endurance strength test (mean time 233+/-22 s for PH rats and 73+/-14 s for SI rats). There was a negative correlation between body weight and results on the inclined plane for the PH rats. There were no significant differences between housing types with respect to CO/CR ratios. In conclusion, the large pen represents an environment that stimulates physical activity and more varied behaviour, which should be beneficial for the welfare of the animal.
The ontogeny of two stereotypic patterns, wire-gnawing and jumping, was studied in 24 laboratory mice: six males and six females each of two closely related outbred strains, kept under standard housing conditions, a conventional albino strain (ICR) and a nude, athymic mutant (ICR nu; hereafter: NU). All 24 individuals developed wire-gnawing after weaning at 20 d of age. In ICR one female and in NU five males and three females additionally developed jumping. ICR developed wire-gnawing between the age of 20 and 30 d, in NU jumping started at the age of 20 d, but intense jumping and wire-gnawing comparable to that of ICR did not develop in NU before the age of 40–50 d. Within each strain there was no significant difference between males and females with respect to the development of stereotypic behaviour. By contrast, ICR showed significantly more wire-gnawing but less jumping than NU.
Stereotypy level increased with age up to a mean of 10.7 % of total activity in ICR and up to 7.4 % in NU at 100 d of age. However, there was huge inter- and intra-individual variability with respect to all parameters assessed in this study, i.e. total duration, number of bouts and bout length of the two stereotyped patterns.
Wire-gnawing developed from outside-directed explorative climbing at the cage lid, whereas the source behaviour pattern (Mason 1991 a, Anim. Behav. 41, 1015–1037) of jumping was outside-directed explorative rearing at the cage wall. At 20 d of age, before the onset of stereotypy development, ICR showed significantly more climbing but less rearing than NU. Physical retardation of NU at weaning may account for decreased climbing ability during early ontogeny, and hence for the retarded development of wire-gnawing. The difference in early experience with either of the two patterns rather than genetic effects may be responsible for the qualitative difference between the strains with respect to the form of later stereotypy.
Although there are many studies on the running wheel in laboratory animals, it is not clear if a running wheel should be provided for golden hamsters kept as pets. Unlike laboratory animals, golden hamsters kept as pets usually have larger cages, more varied food, and are kept singly. In this study, 10 sister-pairs of golden hamsters were kept singly in large enriched cages with a functional or a non-functional large running wheel. Using video-recordings, the behaviour of hamsters of both groups was compared. Hamster females with a functional wheel showed significantly less climbing and stereotypical bar-mouthing than females with non-functional wheels.In order to compare the physical condition of the females, they were regularly mated and raised up to four litters before they stopped reproducing. Body masses did not differ between the groups, but females with functional wheels had significantly larger litters. Offspring growth did not differ, probably because the females decreased running in the wheel during pregnancy and stopped running completely during lactation. Therefore, we conclude that a large well-constructed running wheel will have no detrimental effect on golden hamsters kept in large and enriched cages with ad libitum access to adequate food and water. On the contrary, the running wheel may have had a beneficial effect on the well-being of the hamsters since it significantly decreased stereotypic bar-mouthing.
Several species of mice build burrows, however, little is known about the motivation underlying this behaviour. This study had two aims: (1) to investigate whether burrowing constitutes a behavioural need, that is, whether mice were motivated to perform the behaviour of burrowing per se, or whether it is the functional consequences of burrowing that motivate the behaviour; (2) to determine the strength of motivation that laboratory mice have for burrowing. In Experiment 1, eight BALB/c mice were placed individually into a start cage connected to two burrowing compartments containing peat. During Phase 1, the mice had access to only one compartment, and during Phase 2, access to only the second. At the beginning of Phase 3, the burrows in one of the compartments were destroyed and the mice given access to both. The duration of burrowing remained unchanged throughout all three phases, and the number of burrowing bouts significantly increased. During Phase 3, there was no significant difference between burrowing in the compartments containing the intact or the destroyed burrows. These data confirmed that laboratory mice readily build burrows when given the opportunity, and indicate this behaviour constitutes a ‘behavioural need’. In Experiment 2, the strength of motivation for burrowing was examined in five CB57 mice using an operant technique in which a single mouse within a group could work to gain access to burrowing substrate. Despite increasing cost of gaining access, the mice continued to work to visit the burrowing substrate. The slope and area under the demand function indicated that the motivation to build burrows was high. These findings indicate that if studies require laboratory mice to express a full behavioural repertoire, or to avoid compromises of welfare, mice should be provided with the opportunity to perform burrowing wherever practicable.
A variety of recent rodent studies have suggested the use of an enriched environment as a strategy to increase the welfare of captive animals. However, a number of standard procedures of environmental enrichment are applied without taking into account the etho-ecological, species-specific, needs of laboratory animals. The aim of the present study was to evaluate the age and sex differences in the utilisation of a physically-enriched environment, consisting of four differently-shaped plastic compartments: a central chamber, a circle, a running wheel and a tower. These compartments are characterised by features (e.g. size, lightness, presence of food, opportunity to perform physical activity) of eco-ethological relevance for the mouse, the most common laboratory species. Presence and activity in each cage compartment during 5 consecutive days were assessed in juvenile (35 days old) and adult (90 days old) CD-1 mice of both sexes. Mice explored all the compartments, spending most of the time in the central chamber and making an extensive use of the running wheel. Juveniles of both sexes and adult males showed a prominent occupation of the central chamber, where food and sawdust were located, and they widely used it to sleep, suggesting that food availability might be a relevant factor in driving their choice of the resting location. Conversely, adult females displayed a more complex utilisation profile and preferentially stayed in the tower while inactive, suggesting that safety needs, that the covered structure of this compartment probably cater for, may be more relevant for them than availability of food and water resource. These findings indicate that in laboratory mice the features of an enriched environment are differentially relevant according to age and sex and, thus, may exert a different impact on their psycho-physical welfare.
At 21 days of age, 16 pairs of male laboratory mice of the ICR strain were weaned and allocated to four treatment groups in a 2×2 factorial design matched for genetic background (litter) and body weight. Factor one was the hardness of the food pellets with a significant 2.5-fold difference between soft and hard feed. Factor two was the environment, with half of the mice being kept in barren standard cages, while the other half were additionally provided with a cardboard tube. Subjects were videotaped during the full 12-h dark period on three occasions: 3 days after weaning, when stereotypies start to develop (24 days), at an early stage of stereotypy development (34 days), and when adult with fully established stereotypies (80 days). Since feed hardness had no effect on time spent feeding, the absence of an effect of the feeding treatment on stereotypic wire-gnawing remains inconclusive with respect to the role of feeding motivation in the development of this stereotypy. The interaction between the development of feeding and wire-gnawing, respectively, does not, however, suggest a strong relationship. In contrast, enrichment significantly reduced stereotypic wire-gnawing in adults by 40% (F=4.47, df=1,26, p
Claims about animal welfare based on data regarding the pituitary-adrenocortical axis should be viewed with scepticism because of the lack of consistency between the results of different studies. Occasional sampling of blood does not give an accurate description of the episodic nature of corticosteroid secretion. Too little is known about how chronic stress affects the activity of the pituitary-adrenocortical axis, or whether changes in mean daily level or in the nature of the secretory episodes are most important. More attention should be paid to basic research to understand the nature of this biological system rather than to premature attempts to “measure” animal welfare by corticosteroid values.
Although the physiological and behavioural changes that can indicate poor welfare are generally agreed upon, using these measures in practice sometimes yields results that are hard to interpret. For example, different types of measure may suggest quite different things about an animal's welfare. Such contradictions are often due to the differing properties of the variables being measured. How each variable responds to a stressor can be affected by several factors - the type of unpleasant stimulus to which the animal is exposed; when and for how long exposure occurs; the animal's psychological state, eg does it feel that it is in control?; and the time at which the measurement is made, relative to the stressor. Typical responses also often differ between species and between individuals, and may even change in a single individual over time. Furthermore, some responses used to assess welfare lack specificity: they can be elicited by neutral or even pleasant events as well as by aversive ones. Appreciating these factors is vital when designing experiments, when choosing what to measure along with each welfare variable, and when interpreting results. Even after taking these factors into consideration, interpreting a result can still be difficult. One approach then is to consider the effects on welfare of the changes measured, eg if there is immunosuppression, does the animal succumb to disease? Another is to use the animal's behaviour to indicate its preference for, or aversion to, particular environments. Ultimately, however, interpreting welfare measures involves subjective judgements which will be influenced by the nature of our concern for the animal under consideration. By raising these problems, we hope that this review will highlight and clarify the apparent contradictions that sometimes emerge in scientific studies of animal welfare, and help researchers improve the designs of their experiments for the benefit of the animals concerned.
Prolonged interaction with cage bars by captive mammals (usually classed as stereotypic) may reflect poor welfare. Such behaviour may arise from motivation to investigate the external environment or to escape captivity. However, these hypotheses have not been explicitly tested. We raised mice, Mus musculus, to adulthood in modified laboratory cages with two sets of bars at the top and side of the cage. One set provided a potential escape route, and half of each set was backed by Perspex to reduce cues from the external environment. We predicted where mice should interact with the bars according to their motivational priorities. Body weights were recorded weekly to study the relationship between physical development and bar-related behaviour. Serum corticosterone was measured to monitor the effect of bar-related behaviour on stress physiology. Mice preferred to interact with bars where external cues were detectable. As adults, mice responded more to the bars providing a potential exit, though this was affected by the exit location. Corticosterone titres were higher in mice whose potential exit was situated at the cage top. Response to the bars was apparently restricted by the physical development of mice, particularly among those whose potential exit was situated in the cage top. © 1999 Elsevier Science B.V. All rights reserved.
Stereotypies are repetitive, invariant behaviour patterns with no obvious goal or function. They seem to be restricted to captive animals, mentally ill or handicapped humans, and subjects given stimulant drugs. In this respect they are abnormal, although possibly the product of normal behavioural processes. Stereotypies are often associated with past or present sub-optimal aspects of the environment, and have been used as a welfare indicator. It has been hypothesized that stereotypies have beneficial consequences which reinforce their performance, although other means, such as positive feedback, may equally explain their persistence. Empirical evidence links them with lowered awareness of external events, and reduced arousal and distress. However, as most of this evidence is correlational it remains uncertain that the stereotypies are themselves the cause of coping. Furthermore, they are heterogeneous in source of origin, proximate causation and physical characteristics, and they change over time in important respects, becoming more readily elicited by a wider range of circumstances. Therefore the properties of one stereotypy are not necessarily those of another.
Three groups of six pairs of adult male laboratory mice of the ICR-strain kept in standard laboratory cages were selectively prevented from stereotypic wire-gnawing for 1, 5 or 10 days, respectively. Behaviour was observed throughout the 12 h dark period one day prior to prevention, on day 1, 4 or 9 (depending on the group) during the period of prevention and on post-inhibitory day 1 and 3. Prior to prevention wire-gnawing was positively correlated (P<0.05) with total activity and climbing. During prevention all three groups showed a significant reduction in total activity (non-stationary; P<0.05) and climbing (P<0.001) and significantly enhanced inactivity (lying motionless; P<0.05). However, the decrease in total activity was positively correlated with base levels of wire-gnawing only on day 1 (P<0.01) but not at later stages of prevention. Similarly, climbing during prevention was positively correlated (P<0.05) with base levels of wire-gnawing on day 1 and 4 but not on day 9 of prevention. These results indicate that the mice only gradually adapted to the new situation. On post-inhibitory day 1 all three groups resumed wire-gnawing at pre-treatment base levels with performance following the same time course throughout the dark period but with significantly reduced peak performance (P<0.05). In the light of motivational theory these results shed doubt on the general validity of the coping hypothesis. Two alternative explanations are discussed.
Artificial weaning in laboratory mice elicits increased levels of exploratory and escape behaviour. Under barren housing conditions patterns of exploration and escape subsequently develop into stereotypic behaviour. Weaning weight in wild house mice,Mus musculus domesticus, is known to affect offspring fitness, thus reduced weaning weight represents a risk to fitness. In male ICR-mice,Mus musculus, precocious weaning 3 days prior to standard weaning age tended to decrease growth rate in the long term, and differences in weaning weight of mice weaned at the standard age persisted into adulthood. Both plasma corticosterone levels 48 h after weaning and adult stereotypy levels were higher in precociously weaned mice, but also in animals weaned at the usual age but at a low weight. These results suggest that potential costs in terms of fitness may affect stress levels at the onset of stereotypy development and predispose ICR-mice to perform stereotypies at a high level when adult.
Rats, hamsters, gerbils and guinea pigs were housed in activity cages and fed 1 hr each day. By the end of the 21-day experimental period, 86, 100, 70 and 70% of rats, hamsters, gerbils and guinea pigs had developed lesions in the glandular stomach. This procedure was thus capable of producing lesions in species other than the rat, thereby increasing the value of the procedure as an ulcerogenic technique.
The importance of a commodity, as perceived by animals, can be determined by measuring the amount of work animals are prepared to perform to gain access to that commodity. In the present study, this method is extended to establish how animals perceive the importance of increasing amounts of one commodity, that is, additional space. The behavioural demand functions of caged laboratory mice,Mus musculusfor additional space ranging from 196 cm2to 1600 cm2on fixed-ratio schedules ranging from 5 to 80 switch operations were determined. At all fixed-ratio values, the mice worked economically and gained access to additional space on several occasions within each 1-h observation session. The amount of access gained decreased as the work required increased, but the slope of the function (−0.347) was sufficiently shallow to indicate that additional space was regarded by the mice as a highly important commodity. The frequency of visits and the time spent in the additional space were significantly different between the sizes of additional space offered, but unexpectedly, these differences were small. In addition, the elasticity coefficients were not significantly different between the sizes of additional space. The absence of large differences in response to disparate sizes of additional space may indicate that the mice may have (1) been motivated to escape their home-cage, (2) been motivated to search for unavailable resources, or (3) perceive the different amounts of additional space as nearly equally (non-)rewarding. Time of day had a significant effect on the responses of the mice in that towards the end of the active phase, the additional space was visited less frequently and for shorter periods indicating a temporally based change in motivational status or efficiency of behaviour. It is argued that these results support previous evidence that laboratory mice are highly motivated to explore and subsequently monitor areas made accessible to them, regardless of size and, to some extent, content.
From welfare perspective group housing of mice is preferred over individual housing. Group housing of male laboratory mice, however, often leads to problems due to excessive aggressive behaviour. In our search for management and housing modifications to decrease aggression in group-housed male laboratory mice, we have tested the effect of two types of environmental enrichment—nesting material and shelter—on aggressive behaviour after cage cleaning and after a 1h isolation period. Severity of wounds, urinary corticosterone levels, body weight, food and water intake and several post-mortem parameters were also monitored.The results indicated that type of enrichment strongly affected both aggressive behaviour and physiological parameters. Overall, nesting material reduced aggressive behaviour, while a shelter increased aggressive behaviour compared to control housing. This effect was also reflected in the number of wounds counted. Furthermore, during shelter housing mice gained less body weight, drank less and showed higher corticosterone levels, while in housing conditions with nesting material, mice ate less. We conclude that providing male mice with nesting material reduces aggression between male mice, and may, thus, be promoted as being beneficial to their physical health and psychological well-being.
O2 and CO2 concentrations were measured in burrows of golden hamsters (Mesocricetus auratus, W.) simultaneously with body temperature. In sealed burrows of euthermic golden hamsters daily mean concentrations of 15.1 +/- 1.2% O2 and 5.7 +/- 1.2% CO2 were measured, the extreme values amounting to 10.0% O2 and 10.8% CO2. The gas composition showed a daily rhythm. During hibernation, the gas composition of the burrow changed significantly to 20.0 +/- 0.5% O2 and 1.8 +/- 0.8% CO2.
Wheel-running and direct observation of animals in their home cages were used to measure the activity of golden hamsters through the oestrous cycle, pregnancy and pseudopregnancy. Both methods showed that the pro-oestrous and oestrous days of the cycle were days of increased activity. Levels of hweel-running fell immediately after copulation and were low throughout pregnancy and pseudopregnancy. Except for bar-chewing, categories of behaviour scored in the home cages did not show a comparable decline. Nest-building increased during pregnancy. Sleeping was reduced on days 5 and 10 of pregnancy. The differences between the two methods of recording activity are discussed, as are the physiological bases of the changes in behaviour.
The present paper describes the effects of animal house routine stressors on adult golden hamsters during activity time (2 hrs after lights off) and rest time (2 hrs after lights on). In addition, for determination of norm values, the circadian rhythms of the stress indicators heart rate, core body temperature and general activity of unstressed animals were telemetrically registered via implanted transmitters. The three circadian patterns of the nocturnal golden hamster under L:D = 12:12 were unimodal with a main peak after lights off. The physiological norm values (mean over 24 hours +/-SD) were: heart rate 324 +/- 18 bpm, core body temperature 37.5 +/- 0.5 degrees C and activity 114 +/- 123 units/5 min. The mean body temperature of females was significantly higher (0.4 degree C) and its mean activity level was significantly (40%) lower than that of males. The stress responses were dependent on the time of day and on the kind of stressor. The stress responses were significantly stronger during the rest time of the animals (i.e. light period), and it resulted in the subsequent ranking of stressors: handling < vaginal smear < intruder/resident confrontation < cage changing < grouping. There were no sex-dependent stress response differences. The results of this study were compared with identical investigations on the social Mongolian gerbil (J. Exp. Anim. Sci. 1996/97; 38: No. 3).
Golden hamsters, Mesocricetus auratus, ran more in wheels with the floor covered by a plastic mesh than in wheels with the usual rods. This preference was evident both in tests with a single wheel and in tests when the animals were offered a choice between two wheels. Phase shifts following a 3h confinement to a novel wheel were greater if the novel wheel had the plastic cover.
Voluntary wheel running by animals is an activity that has been observed and recorded in great detail for almost a century. This review shows that it is performed, often with startling intensity and coordination, by a wide variety of wild, laboratory and domestic species with diverse evolutionary histories. However, despite the plethora of published studies on wheel running, there is considerable disagreement between many findings, thus leading to a lack of consensus on explanations of the causality and function. In the initial part of this review, I discuss the internal and external factors that may be involved in the causality of this behaviour, with an emphasis on disparities in both the factual and theoretical development of the subject. I then address the various proposed functions of wheel running, again highlighting evidence to the contrary. This leads to the conclusion that any single theory on the basis of wheel running is likely to be simplistic with little generality. I then present a novel, behaviour-based interpretation in which it is argued that wheel running has no directly analogous naturally occurring behaviour, it is (sometimes) performed for its own sake per se rather than as a redirected or substitute activity, and studies on motivation show that wheel running is self-reinforcing and perceived by animals as 'important'. This review proposes that wheel running may be an artefact of captive environments or of the running-wheel itself, possibly resulting from feedback dysfunction. I also discuss the ubiquity and intensity of its performance, along with its great plasticity and maladaptiveness, all indicating that if it is an artefact, it is nevertheless one of great interest to behavioural science. Copyright 1998 The Association for the Study of Animal Behaviour.
Rodents used in biomedical research are typically reared in small cages that lack key features of their natural habitats. These conditions impose constraints on behaviour and brain development, resulting in altered brain functions. In this article, evidence for three different ways in which barren housing conditions interfere with brain development and behaviour is reviewed. Early environmental deprivation, thwarting of behavioral response rules, and disruption of habitat-dependent adaptation processes are shown to result in aberrant or maladaptive brain functions. Current standard housing conditions could therefore compromise the utility of rodents for research, especially in behavioural neuroscience. However, a better understanding of the animals' needs and of the environmental factors involved in the control of behaviour could offer a biological basis for refinement.
Running wheels are frequently used in behavioural and physiological experiments. The function of wheel-running activity in laboratory animals is controversial. In the present long-term study, the influence of this activity was evaluated in male golden hamsters over a period of 52 weeks. Four months after the start of the experiment, hamsters with access to running wheels were significantly heavier than those without these wheels. In addition, food consumption nearly doubled. The absolute values of fat-free mass (FFM), total body water (TBW) and crude fat mass (CFM) increased. However, in contrast to these absolute differences, the relative values were never different and general body composition was therefore unaffected by running-wheel activity. Different organ masses were established for absolute values of kidneys, testes and epididymis; possible effects on reproduction are discussed. The present data indicating improved physical condition leads to the assumption that a running wheel is a useful enrichment, enhancing animal welfare in the golden hamster.
This paper introduces automated observations in a modular home cage system as a tool to measure the effects of wheel running on the time distribution and daily organization of cage floor locomotor activity in female C57BL/6 mice. Mice (n = 16) were placed in the home cage system for 6 consecutive days. Fifty percent of the subjects had free access to a running wheel that was integrated in the home cage. Overall activity levels in terms of duration of movement were increased by wheel running, while time spent inside a sheltering box was decreased. Wheel running affected the hourly pattern of movement during the animals' active period of the day. Mice without a running wheel, in contrast to mice with a running wheel, showed a clear differentiation between novelty-induced and baseline levels of locomotion as reflected by a decrease after the first day of introduction to the home cage. The results are discussed in the light of the use of running wheels as a tool to measure general activity and as an object for environmental enrichment. Furthermore, the possibilities of using automated home cage observations for e.g. behavioural phenotyping are discussed.
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- Gattermann
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