Why do rabbits need a friend?

Georgina Mills reports on new research showing the benefits of housing rabbits together.

The effect of transport on the quality of rabbit meat.

The analyzed material included 40 hybrid rabbits slaughtered at the age of 90 days. The control group was transported directly after weaning, while the transport group was transported directly prior to slaughter. The experiment was designed to assess the transport stress, carcass and meat quality implications, taking into account the muscle type and sex. The transported animals were characterized by a higher level of blood cortisol, glucose and triglycerides (P < 0.0001), and a lower level of insulin (P < 0.0001) compared to the control group. In the presented study the time post-mortem affected the pH decline in both rabbit groups (P < 0.0001). The lightness, redness and yellowness of rabbit meat were affected by the transport (P < 0.0001, P = 0.001 and P < 0.0001). The percentage of free water and its share in the total water was higher for the non-transported rabbits compared to the transported ones (P < 0.0001). Moreover, the meat from the control group was characterized by greater plasticity compared to the transport group (P = 0.003). The chemical composition of rabbit meat was not changed by the effect of transport (P = 0.643-0.979). To conclude, the quality traits of meat from the transported hybrid rabbits clearly indicated the development of dark firm and dry-like lower quality of meat.

Sequelae of Occult Aggression Disqualifying Young, Socially Housed, Female New Zealand White Rabbits (Oryctolagus cuniculus) from Participation in Dermal Toxicology Studies.

International animal welfare organizations and federal, regional, and institutional oversight bodies encourage social housing of gregarious species, such as New Zealand white rabbits (Oryctolagus cuniculus), to promote animal wellbeing in research, teaching, testing and farming settings. At our institution, 2 groups of female New Zealand white rabbits (approximate age, 11 wk; mean weight, 2.35 kg), compatibly paired at the vendor for 5 wk, were paired in caging or group-housed in a floor pen. The rabbits appeared compatible, demonstrating primarily affiliative behaviors throughout 6 wk of daily observations. However, occult aggression that occurred between daily observations or nocturnally resulted in skin wounding. The skin injuries, first identified during prestudy clipping of fur from the back of each rabbit 6 wk after arrival, disqualified every animal from participation in skin toxicology and muscle implantation studies. Success meeting scientific research requirements while promoting animal welfare and health when socially housing New Zealand white rabbits requires examining the behavioral repertoire of their wild counterparts, European rabbits. Factors including age, sex, and housing density influence territoriality, dominance hierarchy, social ranking, and natural, agonistic, injurious, behavioral tendencies. IACUC and other relevant oversight bodies, researchers, and animal care staff should consider this case study and the species-specific natural history of New Zealand white rabbits when assessing the harm and benefit of social housing in regard to research utility and animal welfare.

Relocation and Hair Cortisol Concentrations in New Zealand White Rabbits.

To investigate how long relocation modified hair cortisol concentrations in New Zealand white rabbits, 19 rabbits were subjected to a change in their breeding facility at the beginning of the trial and then were kept under stable environmental conditions. Hair samples were collected at the time of arrival to the nonhuman animal facility and at 40-day intervals from the same skin area for up to 440 days after the animals' arrival to the facility. A period effect on the hair cortisol concentration was found (p < .01). The transfer of the rabbits to the new facility might have induced an increase in the hypothalamic-pituitary-adrenal axis activity (p < .01). A second increase in hair cortisol concentration (p < .01) occurred at 320 days, after a change of personnel at the facility that occurred at 280 days, which was the only environmental change. The relocation of rabbits to the facility resulted in a stress response leading to elevated cortisol levels. The effect of relocation on mean cortisol concentrations was exhausted within 120 days when all environmental factors were kept stable.

Social Behavior of Adult Male New Zealand White Rabbits Housed in Groups or Pairs in the Laboratory.

Rabbits are usually singly housed in laboratories, but a new emphasis on providing social housing for social species has prompted exploration of alternative housing for this species. However, a paucity of literature on the social behavior of rabbits in captivity has prevented scientific-based recommendations for appropriate housing. This study involved a descriptive analysis of the social behavior of rabbit bucks in the laboratory in 3 different housing situations: in groups in pens, in pairs in cages, and singly in cages. Based on study observations and the natural history of wild rabbits, bucks engage in affiliative social behaviors, but current caging may not allow for the expression of species-typical behaviors, thereby resulting in continued aggression.

Effects of semi-group housing and floor type on pododermatitis, spinal deformation and bone quality in rabbit does.

The most common housing system for reproduction rabbits, individual cage housing on a wire floor, is increasingly scrutinized because of its potential detrimental impact on animal welfare. We compared three types of housing: (1) individual cage housing on a wire floor (3952 cm2/doe, maximum roof height 63 cm, one 1000 cm2 plastic footrest/doe), (2) semi-group housing on a wire floor (5000 cm2/doe, roofless, one 1000 cm2 plastic footrest/doe) and (3) the same semi-group housing, but with a fully plastic slatted floor. In all housing systems, does had free access to an elevated platform. In the semi-group housing pens, four does were housed communally during 21 days of the reproduction cycle (to allow more space for locomotion and to increase opportunities for social contact), and individually during the other 21 days of the cycle (to minimize doe-doe and doe-kit aggression that peaks around kindling). In all, 24 Hycole does were included per system. The does entered the experiment at 203 days of age (after their first parity). The experiment consisted of four reproductive cycles, ending at 369 days of age. Pododermatitis was scored in cycles 1, 2 and 4. At the end of the 4th cycle the does were euthanized and X-rays were taken to assess spinal deformation. Tibia and femur length, width and cortical thickness were determined and bone strength was assessed using a shear test, as a measure of bone quality. Although severe pododermatitis was absent, the prevalence of plantar hyperkeratosis (hair loss and callus formation) at the end of the 4th cycle was much greater on the wire floor (65% and 68% for semi-group housing and individual cages, respectively) than on the plastic floor (5%, P<0.0001), even though the wire floors were equipped with a plastic footrest known to decrease hyperkeratosis. In contrast to our expectations, semi-group housing did not affect the prevalence of spinal deformations (P>0.10), but in line with our expectations bone quality was affected favourably by semi-group housing. The tibial cortex (and to a lesser extent the femoral cortex) was thicker in semi-group housing than in individual cages (1.45, 1.46 and 1.38 mm for semi-group housing on wire, semi-group housing on plastic and individual housing on wire, respectively, P=0.045). What this increase in cortical thickness means in terms of doe welfare requires further study, as it may reflect an increase in activity resulting either from increased space for locomotion, or from fleeing aggressive pen mates.

Rabbit genome analysis reveals a polygenic basis for phenotypic change during domestication.

The genetic changes underlying the initial steps of animal domestication are still poorly understood. We generated a high-quality reference genome for the rabbit and compared it to resequencing data from populations of wild and domestic rabbits. We identified more than 100 selective sweeps specific to domestic rabbits but only a relatively small number of fixed (or nearly fixed) single-nucleotide polymorphisms (SNPs) for derived alleles. SNPs with marked allele frequency differences between wild and domestic rabbits were enriched for conserved noncoding sites. Enrichment analyses suggest that genes affecting brain and neuronal development have often been targeted during domestication. We propose that because of a truly complex genetic background, tame behavior in rabbits and other domestic animals evolved by shifts in allele frequencies at many loci, rather than by critical changes at only a few domestication loci.

Small mammal training in the veterinary practice.

Exotic small mammal patients can experience a great deal of anxiety and fear during a visit to a veterinary practice. The stressful experience may continue at the client's home during medication routines. The experience is at times so stressful to the animal that it damages the relationship of trust with its caregiver. This outcome can be changed through the thoughtful use of desensitization, counterconditioning, environmental management and positive reinforcement training of health care behaviors both in the veterinary practice and in the animal's home. Together the veterinarian and the client can create a low stress experience.

Private heat for public warmth: how huddling shapes individual thermogenic responses of rabbit pups.

BACKGROUND: Within their litter, young altricial mammals compete for energy (constraining growth and survival) but cooperate for warmth. The aim of this study was to examine the mechanisms by which huddling in altricial infants influences individual heat production and loss, while providing public warmth. Although considered as a textbook example, it is surprising to note that physiological mechanisms underlying huddling are still not fully characterised. METHODOLOGY/PRINCIPAL FINDINGS: The brown adipose tissue (BAT) contribution to energy output was assessed as a function of the ability of rabbit (Oryctolagus cuniculus) pups to huddle (placed in groups of 6 and 2, or isolated) and of their thermoregulatory capacities (non-insulated before 5 days old and insulated at ca. 10 days old). BAT contribution of pups exposed to cold was examined by combining techniques of infrared thermography (surface temperature), indirect calorimetry (total energy expenditure, TEE) and telemetry (body temperature). Through local heating, the huddle provided each pup whatever their age with an ambient "public warmth" in the cold, which particularly benefited non-insulated pups. Huddling allowed pups facing a progressive cold challenge to buffer the decreasing ambient temperature by delaying the activation of their thermogenic response, especially when fur-insulated. In this way, huddling permitted pups to effectively shift from a non-insulated to a pseudo-insulated thermal state while continuously allocating energy to growth. The high correlation between TEE and the difference in surface temperatures between BAT and back areas of the body reveals that energy loss for non-shivering thermogenesis is the major factor constraining the amount of energy allocated to growth in non-insulated altricial pups. CONCLUSIONS/SIGNIFICANCE: By providing public warmth with minimal individual costs at a stage of life when pups are the most vulnerable, huddling buffers cold challenges and ensures a constant allocation of energy to growth by reducing BAT activation.

Use of different areas of pen by growing rabbits depending on the elevated platforms' floor-type.

The addition of platforms to rabbit cages increases their accessible area and provides rabbits greater freedom and mobility. Different types of platforms enable rabbits to situate themselves where they are most comfortable. The objective of this experiment was to analyse preference of growing rabbits between different areas of the pen depending on the elevated platforms' floor-type. Pens with a basic area of 0.84 m2 were equipped with platforms of 0.42 m2. Three types of flooring of the elevated platforms were used as treatments: deep-litter floor and an open wire-net floor (Experiment 1), and a deep-litter floor and a wire-net floor with a manure tray beneath it (Experiment 2). Growing rabbits (n = 168; 42 per treatment) between the ages of 5 and 11 weeks were studied, based on 24 h video recordings from infra-red cameras (one recording per week) applying scan sampling method with a frequency of 30 min. When the platform was deep-litter, significantly (P < 0.001) more rabbits used the area under the platform (53.7% and 54.3% in Experiments 1 and 2, respectively) than stayed on the platform (16.7% and 7.6%). In treatments of wire-net platform with and without tray beneath the platform also significantly (P < 0.001) more rabbits stayed under the platform (43.7% and 34.7%, respectively) than on the platform (19.5% and 29.9%, respectively). The differences from the expected 33.3% staying on the platform or under the platform were significant at least at the level of P < 0.05. The results show that the wire-net platform with the manure tray provides the optimal environment as it leads to the rabbits spreading themselves more evenly in the pen (i.e. the platform expands available floor area) without the risk of soiling from above, and without adverse effects on heat dissipation, and with the possibility of seeking cover when desired.

[Animal assisted therapy in a long-term care nursing home]. / Zoothérapie dans un Centre de long séjour.

Animal assisted therapy sessions have been set up at the Bellevaux nursing home in Besançon. The project has required a number of specific procedures and training courses to be put in place as well as the involvement of different departments. The sessions give real pleasure to the residents and produce interesting results.

Intrauterine position influences anatomy and behavior in domestic rabbits.

In several rodent species, the sexual differentiation of a female offspring is known to be affected in utero by the testosterone produced in adjacent male littermates. The aim of this study was to investigate the effect of male neighbors on the sexual differentiation in domestic rabbits. For this, the intrauterine position (IUP) of a female offspring from unilaterally ovariectomized, multiparous mothers was determined by their birth order. Depending on the sex of the adjacent fetuses, pups were divided into 4 groups: 1. Males. 2. 2 M females (females with 2 adjacent males), 1 M females (females with 1 male neighbor), and 0 M females (females with zero adjacent male). Pups' anogenital distance (AGD) was measured at birth and on Day 180 postpartum, when spontaneous chin marking activity was also measured. Our results revealed that AGD was a reliable indicator of sex as male pups had larger AGD than females, both at birth and later on. Adjacent male fetuses had significant effect: the more adjacent male fetuses females have had the longer AGD they possessed. AGD at birth was a good predictor of AGD and behavior of adults, as 2 M does showed the longest AGD and the highest chin marking activity among females. We concluded that, similarly to rodents, proximity to males in utero affects both anatomy and behavior in rabbits.

Effects of husbandry and management systems on physiology and behaviour of farmed and laboratory rabbits.

The major issues regarding the welfare of both farmed and laboratory rabbits are reviewed, according to husbandry and management systems. The main stressors that can affect welfare and homeostatic responses in rabbits are also reviewed. An overview of the most widespread housing systems for both farmed and laboratory rabbits is presented. The main problems related to housing and management are identified, in particular those related to individual and group housing, space requirements and group size, as well as human-animal interaction. The effects of psychological and physical stressors on physiology and behaviour are illustrated through examples in various rearing conditions. Psychological stressors include social stress and fear, while physical stressors include environmental variables such as housing system and climatic factors, i.e. heat. Welfare indicators are identified that can be monitored to determine the effects of individual and environmental variables on the animals' possible coping strategies. Physiological indicators include the neuro-endocrine and psycho-neuro-immuno-endocrine measurements, while behavioural indicators include the behavioural repertoire and responses to behavioural tests. Some possible ways to enhance welfare are indicated, such as enrichment of the environment and improved handling procedures.

Neuroendocrine regulation of estrous behavior in the rabbit: similarities and differences with the rat.

In this review, we compare the neuroendocrine control of estrous behavior in the rabbit, a reflex ovulator, and the rat, a more commonly studied spontaneous ovulator. Although the hormonal control of estrous behavior in both species is similar, notable differences include the absence of a stimulatory effect of progesterone (P) on sexual behavior in the rabbit and the retention of sexual behavior in a substantial proportion of female rabbits after ovariectomy. The ventrolateral component of the ventromedial hypothalamus (VMH) and an adjacent region caudal to it appear to be critical estrogen (E)-responsive regions for lordosis in the rat and rabbit, respectively. In both species the effects of E and P are largely mediated by the genomic action of their receptors (ER and PR), and in both species E similarly regulates the expression of these receptors. The prolonged, E-stimulated estrous of the rabbit is terminated after mating by unknown mechanisms, while the brief estrous of the rat is triggered by the proestrous peak of P and terminated by both the decline in P and the downregulation of hypothalamic PR. In both species, P most likely inhibits estrous behavior during pregnancy, and postpartum estrous may be triggered by a stimulatory effect of E coinciding with the withdrawal of P-mediated inhibition. Estrous behavior is inhibited in both species during lactation, most likely by the suckling-induced inhibition of gonadotropin secretion. This comparative approach can reveal neuroendocrine mechanisms underlying estrous behavior that are common to all mammals, while highlighting evolutionary adaptations unique to each species.

Maternal care of rabbits in the lab and on the farm: endocrine regulation of behavior and productivity.

Maternal behavior in rabbits has been well described in the wild, the laboratory, and the farm. Salient characteristics include: (a) the construction of a nest (inside an underground burrow or a box), composed of straw/grass and body hair and (b) the display of a single, brief (ca. 3 min) nursing bout per day. The onset and decline of nest-building in mid and late pregnancy are controlled by specific combinations of estradiol, progesterone, testosterone, and prolactin. Following parturition (kindling) does can mate and become pregnant again. Management strategies have been used on the farm to enhance productivity, impinging on specific reproductive processes (e.g., use of hormones to synchronize estrus, artificial insemination at kindling, doe-litter separation on specific days of lactation to increase sexual receptivity and fertility). Knowledge about the rabbit's reproductive physiology and behavior will be enriched by integrating research coming from the laboratory (where estrus, pregnant-only, or lactating-only animals are the main categories investigated) with studies performed on the farm or research station (where pregnant-lactating rabbits are prevalent). Similarly, the high productivity demands of modern rabbit farms will benefit from the information obtained in the laboratory where specific issues in reproductive neuroendocrinology are explored with methodologies that are not amenable for farm use.