Choice by rats for enriched versus standard home cages: Plastic pipes, wood platforms, wood chips, and paper towels as enrichment items

The purpose of the present study was to determine whether simple additions to the home cages of rats made those cages preferable to standard housing arrangements. Results indicated that most rats preferred cages with wood platforms, wood chips, and paper towels to otherwise identical cages without these items. Wood chips were not, however, practical with the cages used in the present study. Plastic pipes caused no problems but were not preferred by most animals. Both wood platforms and paper towels created no problems and appeared to be useful as enrichment items. The latter were preferred to the former in a direct comparison.     

Maternal aggression in mice: Protection of young is a by-product of attacks at the home site

Lactating female mice attacked male intruders in their home cages but showed little attack behavior either in novel cages or in cages with which they had been familiarized. Presence or absence of young did not determine the occurrence of maternal aggression, whereas attacks on the young by the intruder decreased maternal aggression and increased cannibalism of pups by the dams. Apparently, if the function of maternal aggression in mice is protection of the young, such protection occurs because the pups are in a place where attacks are likely to occur and not because the dam “defends” the young.     

Male mice: Social dominance influenced by strange male odors

Male mice (N = 34) were individually raised with a castrated male cagemate from 5 to 15 weeks of age. Half of them were subsequently isolated in clean cages for 2 weeks, while the other half were housed in isolation for 2 weeks in cages that had previously housed a strange male. After 14 days of isolation-housing, one subject from each condition was placed into pairs and observed for 30 min in a neutral arena. On the next day, weights of their preputial glands were measured. Males exposed to strange male odors were more likely to be dominant during the 30-min test and to have heavier preputial glands than were males that had been housed in clean cages.     

Stress in cynomolgus monkeys (Macaca fascicularis) subjected to long-distance transport and simulated transport housing conditions

The stress associated with transportation of non-human primates used in scientific research is an important but almost unexplored part of laboratory animal husbandry. The procedures and routines concerning transport are not only important for the animals' physical health but also for their mental health as well. The transport stress in cynomolgus monkeys (Macaca fascicularis) was studied in two experiments. In Experiment 1, 25 adult female cynomolgus monkeys were divided into five groups of five animals each that received different diets during the transport phase of the experiment. All animals were transported in conventional single animal transport cages with no visual or tactile contact with conspecifics. The animals were transported by lorry for 24 h at ambient temperatures ranging between 20 degrees C and 35 degrees C. Urine produced before, during and after transport was collected and analysed for cortisol by enzyme-linked immunosorbent assay (ELISA). All monkeys exhibited a significant increase in cortisol excretion per time unit during the transport and on the first day following transport.Although anecdotal reports concerning diet during transport, including the provision of fruits and/or a tranquiliser, was thought likely to influence stress responses, these were not corrobated by the present study. In Experiment 2, behavioural data were collected from 18 cynomolgus macaques before and after transfer from group cages to either single or pair housing, and also before and after a simulated transport, in which the animals were housed in transport cages. The single housed monkeys were confined to single transport cages and the pair housed monkeys were kept in their pairs in double size cages. Both pair housed and singly housed monkeys showed clear behavioural signs of stress soon after their transfer out of their group cages.However, stress-associated behaviours were more prevalent in singly housed animals than in pair housed animals, and these behaviours persisted for a longer time after the simulated transport housing event than in the pair housed monkeys. Our data confirm that the transport of cynomolgus monkeys is stressful and suggest that it would be beneficial for the cynomolgus monkeys to be housed and transported in compatible pairs from the time they leave their group cages at the source country breeding facility until they arrive at their final laboratory destination in the country of use.     

Male-related chemical cues promote sexual receptivity in the female musk shrew

The role of conspecific chemical cues in the activation of sexual behavior was investigated in the female musk shrew (Suncus murinus). In Experiment 1, virgin female musk shrews were exposed to either clean cages or cages recently vacated by an adult male. Regardless of whether the male used for the sexual behavior test was "familiar" to the female (having spent the 24 h exposure in his vacant cage) or "unfamiliar," females exposed to male-related cues received mounts from males significantly sooner than females exposed to clean cages. In Experiment 2, females housed for 24 h in a cage soiled by an adult male allowed males to mount significantly sooner than females housed in a cage soiled by a castrated male, another female, or a clean cage. These results demonstrate that chemical cues, produced exclusively by adult males, promote sexual receptivity in female musk shrews.     

Telemetry Provides New Insights into Entrainment of Activity Wheel Circadian Rhythms and the Role of Body Temperature in the Development of Ulcers in the Activity-Stress Paradigm

Two methods of monitoring the circadian rhythm of activity in rodents: (1) an activity wheel cage, which detects the number of wheel revolutions, and (2) an internal radio transmitter, which records gross motor activity (GMA) of the animal, were compared in both normal circadian cycles and during the development of activity-stress ulcers. Rats were implanted with a biotelemetry transmitter that detected GMA and body temperature (BT) and placed in activity wheel cages. A 12 hour/12 hour light/dark cycle was maintained throughout the experiment. Subjects were subdivided into two groups: (1) unlimited access to activity wheel (AW) cages and (2) locked activity wheel (LW) cages. Following an ad-libitum habituation period, animals were allowed food access for 1 hour/day during the light. In the habituation period, the animals showed higher GMA and BT during the dark phase when housed in AW cages than in LW cages. Both GMA and number of wheel revolutions increased dramatically after the onset of food restriction for the AW animals. There was a deleterious drop in BT in AW animals as the food-restricted period continued and a significant correlation existed between severity of ulcerations and BT. The findings of this experiment demonstrate that the activity wheel imposes an alternation of the circadian cycle, which, in turn, influences rhythmicity through reentrainment. Additionally, in the activity-stress paradigm, a significant drop in BT correlates with severity of ulcerations. A disrupted circadian cycle, involving hypothermia, is proposed as the mechanism underlying the demise of animals in the activity-stress paradigm.     

Telemetry provides new insights into entrainment of activity wheel circadian rhythms and the role of body temperature in the development of ulcers in the activity-stress paradigm

Two methods of monitoring the circadian rhythm of activity in rodents: (1) an activity wheel cage, which detects the number of wheel revolutions, and (2) an internal radio transmitter, which records gross motor activity (GMA) of the animal, were compared in both normal circadian cycles and during the development of activity-stress ulcers. Rats were implanted with a biotelemetry transmitter that detected GMA and body temperature (BT) and placed in activity wheel cages. A 12 hour/12 hour light/dark cycle was maintained throughout the experiment. Subjects were subdivided into two groups: (1) unlimited access to activity wheel (AW) cages and (2) locked activity wheel (LW) cages. Following an ad-libitum habituation period, animals were allowed food access for 1 hour/day during the light. In the habituation period, the animals showed higher GMA and BT during the dark phase when housed in AW cages than in LW cages. Both GMA and number of wheel revolutions increased dramatically after the onset of food restriction for the AW animals. There was a deleterious drop in BT in AW animals as the food-restricted period continued and a significant correlation existed between severity of ulcerations and BT. The findings of this experiment demonstrate that the activity wheel imposes an alternation of the circadian cycle, which, in turn, influences rhythmicity through reentrainment. Additionally, in the activity-stress paradigm, a significant drop in BT correlates with severity of ulcerations. A disrupted circadian cycle, involving hypothermia, is proposed as the mechanism underlying the demise of animals in the activity-stress paradigm.     

An infrared device for detecting locomotor activity

An electronic device for detecting locomotor activity in the home cage of small animals is described. The system involves a dense array of infrared (IR) beams designed to function as switches and capable of penetrating plastic walls of standard rodent cages without operational decrement. The device is reasonably inexpensive, is simple to calibrate, can be used with groups of animals, may be used for extended periods without maintenance, and is reliable with different cages.     

Short-term effects of residence on the testosterone responses to fighting in alpha male guinea pigs

The short-term effects on testosterone (T) levels of (a) taking blood samples, (h) fighting in one's own home cage, and (c) fighting in another male's home cage were examined in eight alpha male guinea pigs, each living together with two females and two subordinate males in their home cages for 4 months. Every male was given two 5-minute agonistic encounters, one in his home cage and one in another male's home cage. After the encounter, intruder males were returned to their home cages. Three blood samples were taken 10 minutes before and 5 and 45 minutes after the agonistic encounters (sampling times were designated as 0, 20, and 60 minutes, respectively). One week before the agonistic encounters were conducted, blood samples were taken from each male on the same time schedule (0, 20, and 60 minutes). The main findings were as follows: (1) the animals showed an increase in T-levels after an agonistic encounter in their home cages and a decline in T-levels after an agonistic encounter in the home cages of other alpha males' irrespective of being the winner or the loser and the degree of escalation during the encounter; (2) the smaller the differences in T-titers between both opponents 10 minutes before the encounter, the more escalated the agonistic encounter.     

Automated analyses of circadian rhythm activity of small arthropods

An automated apparatus is described which measures circadian activity rhythms of small invertebrates in darkness or in the presence of monochromatic light. Back-and-forth activity in tilt cages is measured without physical contact by magnet-activated reed switches. Four such cages are grouped around a mercury pen lamp, whose spectra lines can be selectively filtered, and all are placed in a large enclosure with light-baffling for complete control of intensity and color, delivered to each animal. Activity, measured as reed-switch closures, is counted digitally and punched out periodically onto paper tape. An interactive computer program reads, stores, plots, and further analyzes the data.     

Nuclear family apparatus

The nuclear family apparatus was designed to provide a living arrangement that included fathers as well as other family members. Accordingly, it required generous dimensions so as not to cramp the males and durable materials that could withstand their strength. The apparatus described in this paper is relatively large, strong, easy to keep clean, and safe in its construction. It provides quarters for four rhesus monkey families—the parents and their offspring. Parents are confined to living cages at the rear and ends, but their young may divide their time between living cages and large play areas equipped with motor apparatus.     

The effects of naloxone and cage size on social play and activity in isolated young rats

The effects of large and small housing environments as well as naloxone on social play (as defined by pinning behavior) in isolated postweanling male rats were investigated. Animals housed in small cages played significantly more than those housed in larger cages. This effect was not observed when cage size was reversed. Administration of 0.5, 1.0, and 5.0 mg/kg of naloxone resulted in significant decreases in play behavior as compared to saline controls, both before housing environments were switched, and after. Animals in both isolation conditions were also compared to animals that were socially housed. Isolation was found to increase social play as well as the time spent in active social interaction, but had no effect on locomotor activity. While housing in a small cage increases play behavior, it had no effect on the amount of time spent in active social interaction or on activity. While administration of 0.5, 1.0, and 5.0 mg/kg naloxone to habituated animals differentially housed did not result in an overall decrease in activity, when compared with saline controls, only those animals housed in small cages and injected with the high dose of naloxone differed significantly from controls. In animals having no prior play experience, the activity of animals housed in the large and small cages differed significantly from each other only in the saline and 5.0 mg/kg naloxone conditions. Since naloxone's effect on play behavior was strong, but its effect on activity was not profound, our data suggest that naloxone primarily affects the affective component of play rather than altering activity levels.     

Septal lesions and behavior: effects of presurgical rearing and strain of mouse.

Male mice (C57BL/10J or SJL/J strains) were reared in either enriched social cages or restricted individual cages from 25 days of age until they underwent septal or control surgery 1 mo later. Enrichment differentially altered septal or control behavior as measured by: fluid consumption of water, saccharin, and quinine; performance on a rotorod; and the acquisition of an active avoidance task. The interactions of presurgical history with brain damage were manifested differently in the two strains of mice. The importance of attending more to genetic and presurgical history in attempts to define the effects of brain damage on behavior and to determine the function of brain structures is discussed.     

Components of aggression in chickens and conceptualizations of aggression in general

A refined analysis of the peck order in chickens was offered as a test of the notion that for this species, different responses such as leaping and various types of pecking need not be interchangeable indexes of aggression. Indeed, tests showed that particular response types of the birds were differentially mediated by organismic or environmental factors. In large cages pecking at the body was most frequent by birds that had a home-cage advantage. Contrarily, rates of aggressive leaping were independent of this environmental influence, with males having an advantage over females. Males showed more head pecking than females, but the profile for this sex difference did not resemble the profile for leaping. Correlational analyses revealed that whereas head pecking between testmates was not matched in frequency, leaping was positively related. Finally, the behavior of birds tested in small cages differed from that of the large-cage subjects. Although there was more head pecking in the small cages, males did not have an edge, and leaping was infrequent. Such results indicate that these responses cannot be viewed as interchangeable indicators of aggression in fowl.     

Three cage windows for unobstructed animal photography

Three removable cage windows, which make it possible to photograph captive animals with a minimum of obstruction, are described. They are designed for cages with a hinged or sliding door, or as a built-in fixture in the wall of the cage.     

The effects of urine on aggressive responses by male golden hamsters

Twenty adult male golden hamsters were isolated into individual cages for a period of six weeks, at the end of which time they had introduced into their home cages, on three occasions, a castrated male intruder. On each occasion the castrated intruder was daubed on the anogenital region with urine from one of three sources: (1) intact females, (2) other castrated males, and (3) intact males. Urine from a different source was applied to the castrated intruder on each of the three tests. Resident males consistently showed more aggression, sniffing, and following and less defensive behavior than the intruders. However, aggression by the resident males showed a significant variance over the three urine treatments given to the intruder. It is concluded that like male mouse urine, male hamster urine contains attack-provoking cues, but that unlike that of the mouse, female urine does not appear to be attack-inhibiting in this species.     

On the use of microwave radar devices in chronobiology studies: An application with<Emphasis Type="Italic">Periplaneta americana</Emphasis>

Modified motion detectors can be used to monitor locomotor activity and measure endogenous rhythms. Although these devices can help monitor insects in their home cages, the small size of the animals requires a very short wavelength detector. We modified a commercial microwave-based detection device, connected the detector’s output to the digital input of a computer, and validated the device by recording circadian and ultradian rhythms.Periplaneta americana were housed in individual cages, and their activity was monitored at 18°C and subsequently at 28°C in constant darkness. Time series were analyzed by a discrete Fourier transform and a chi-square periodogram. Q₁₀ values and the circadian free-running period confirmed the data reported in the literature, validating the apparatus. Moreover, the spectral analysis and periodogram revealed the presence of ultradian rhythmicity in the range of 1–8 h.     

Ontogeny of aggressive-sexual behavior between males in lines of Japanese quail (Coturnix coturnix japonica) selected for male mating frequency

Japanese quail from lines bidirectionally selected for high and low male mating frequency and from the random-bred base population were observed in an ontogenetic study of aggressive-sexual behavior. Quail were reared in sex-intermingled flocks until 28 days of age at which time half of the males from each line were housed as all-male flocks and half were transferred to individual cages. At 41 days of age, individually caged males exhibited mounting behavior to win encounters with other males. By 45 days, males from the high and control lines exhibited significantly more aggressive-sexual behavior than those from the low lines. Line x Rearing Experience interactions for mounting behavior at 45 and 56 days of age were due to the individually caged high- and control-line males' winning encounters by mounts; those maintained in flocks rarely mounted. Although some low-line males won encounters by mounts, occurrence of this behavior was infrequent. Males maintained in flocks were placed in individual cages at 57 days of age. When these males were compared with those housed in individual cages from 28 days of age, at 84 days of age and older, the Line x Rearing Experience interaction observed previously disappeared, and only differences among genetic lines were evident. Genetic and rearing experience effects are discussed as influencing agonistic and sexual behaviors.     

An efficient,inexpensive food hopper for monitoring feeding habits of rats

An efficient food hopper designed for the constant monitoring of feeding patterns of rats is described. The apparatus is inexpensive and is designed to attach to standard rat housing cages.     

Effect of early environmental restriction on subsequent behavior in the rat

The Psychological Record - Three groups of rats were raised in (a) unrestricted, (b) community cage, and (c) isolated environments respectively. The community and isolated cages were barren while...