The effects of feeding and housing on the behaviour of the laboratory rabbit

Night-Restricted Feeding Improves Gut Health by Synchronizing Microbe-Driven Serotonin Rhythm and Eating Activity-Driven Body Temperature Oscillations in Growing Rabbits

The circadian misalignment of the gut microbiota caused by unusual eating times in adult animals is related to disease development. However, whether the composition and diurnal rhythm of gut microbiota can be optimized by synchronizing the window period of eating with natural eating habits to reduce the risk of diarrhea remains unclear, especially in growing animals. In this study, 108 5-week-old weaned rabbits (nocturnal animals) were randomly subjected to daytime feeding (DF) and night-restricted feeding (NRF). At age 12 weeks, six rabbits were selected from each group, and caecum and cecal contents, as well as serum samples were collected at 4-h intervals during 24 h. Overall, NRF was found to reduce the risk of diarrhea in growing rabbits, improved the diurnal rhythm and abundance of beneficial microorganisms, along with the production of beneficial metabolites, whereas reduced the abundance of potential pathogens (Synergistes, Desulfovibrio, and Alistipes). Moreover, NRF improved diurnal rhythm of tryptophan hydroxylase isoform 1 and serotonin. Furthermore, NRF strengthened the diurnal amplitude of body core temperature, and promoted the diurnal expression of intestinal clock genes (BMAL1, CLOCK, REV-ERBα, and PER1), and genes related to the regulation of the intestinal barrier (CLAUDIN-1), and intestinal epithelial cell self-proliferation and renewal (BMI1). In vitro simulation experiments further revealed that synchronization of microbial-driven serotonin rhythm and eating activity-driven body temperature oscillations, which are important zeitgebers, could promote the diurnal expression of clock genes and CLAUDIN-1 in rabbit intestinal epithelial cells (RIEC), and enhance RIEC proliferation. This is the first study to reveal that NRF reprograms the diurnal rhythm of the gut microbiome, promotes the diurnal expression of clock genes and tight junction genes via synchronization of microbial-driven serotonin rhythm and eating activity-driven body temperature oscillations, thereby improving intestinal health and reducing the risk of diarrhea in growing rabbits. Collectively, these results provide a new perspective for the healthy feeding and management of growing animals.

Behavioral Effects of Cage Size and Environmental Enrichment in New Zealand White Rabbits

One of the goals of environmental enrichment is to encourage species-typical behaviors, while discouraging abnormal behaviors or stereotypies. Assessing the effectiveness of various enrichment modalities can be challenging, particularly for prey species such as rabbits that exhibit freezing responses in the presence of people. In this study, we housed rabbits in 3 different sized cages and observed their behaviors. The 3 cage sizes were our standard rabbit housing cage, a medium sized cage, and a large run. Based on analysis of the recordings, ethograms were constructed and behaviors were quantified. The rabbits in large runs spent more time performing active, exploratory behaviors (431 ± 74 s) than rabbits in the standard cages(184 ± 55 s). However, space constraints inside research facilities often make it impractical to house rabbits in large runs.Therefore, we decided to explore if enrichment devices could promote the expression of active behaviors, similar to those displayed by rabbits housed in the large runs. We selected 3 devices: a hanging toy, a destructible device, and a dig bin. All 3 enrichment devices promoted more time spent performing active, exploratory behaviors (389 ± 48, 463 ± 50, and 420 ± 44 s,respectively), compared with control rabbits housed without an enrichment device (226 ± 53 s). We also analyzed the fecal glucocorticoids of rabbits after shipping or surgery to determine if enrichment devices could mitigate the physiologic impact of these stressors. We found no significant differences in fecal glucocorticoid levels between rabbits that experienced the stressor and rabbits that did not, or between rabbits with or without enrichment devices. Overall, the provision of largercaging and/or addition of enrichment devices encouraged a broad spectrum of active, species-typical rabbit behaviors, suggestiveof improved animal welfare.

Short term effects of continuous lighting on the cornea of cage-reared laboratory rabbits

This study was to assess the impact on the cornea and eye blink activity of adapting rabbits to continuous lighting (CL) compared to a 14:10 light:dark cycle. Female New Zealand White rabbits (2 to 2.5 kg) were maintained under a light: dark (L:D) cycle or switched to continuous fluorescent lighting (CL) for an average of 17 +/- 2 days. Animal behaviour in their cages was manually recorded using an event marker and in vivo slitlamp biomicroscopy at 40× undertaken in mid-afternoon. Animals were then euthanized and the corneas prepared for scanning electron microscopy (SEM). From images taken at 500× from the central region of the corneas, the number of exfoliating (desquamating) cells and the relative number of different cells with light, medium or dark reflexes were assessed for the corneal epithelial surface, while the number of cells/unit area were assessed for both corneal epithelium and endothelium. Exposure to continuous lighting was associated with higher number of eye blink events (15.7 vs 8.2/15 min) and mild corneal surface alterations evident by biomicroscopy with higher numbers of intra-epithelial 'granules' (32 +/- 14 vs. 4 +/- 3/sq. mm). SEM revealed low numbers of exfoliating cells on the corneal epithelial surface in all CL-adapted animals, but not in L:D controls. Trends were observed for there to be slightly higher numbers of epithelial cells/unit area, higher numbers of small light reflex cells and lower numbers of larger dark reflex cells in CL animals. The corneal endothelium showed no obvious adverse effects in CL-adapted animals but the percentage of 'hexagonal' cells was slightly higher compared to L:D controls. The results indicate that even a short period of exposure of laboratory-raised rabbits to constant lighting can be associated with mild adverse effects on the corneal epithelial surface.

Behaviour of domestic rabbits during 2 weeks after weaning

Thirty three rabbits from five litters that were weaned at the age of 5 weeks were observed. The animals were kept in pens that were enriched with an elevation made of bricks. In total, 150 h of observations made at feeding time (07:30-10:00 and 18:00-20:30 LT, local time) were analysed. A number of affiliative, exploratory, comfort, eating, resting and locomotor behaviours were observed. Agonistic behaviour was not observed. Rabbits showed companion and location preferences: 56 % of animals had a preferred companion, and 84 % preferred a particular place in the pen. Significant effects of group size and time of day on the frequency of some forms of behaviour were found, e.g. rabbits performed comfort behaviours more often in the morning. Sex did not influence the rabbits' behaviour. Correlations were also found between different forms of behaviour, e.g. animals that performed more exploratory behaviours also showed more locomotor behaviours and affiliative interactions.

Effects of rearing feeding programme on the young rabbit females’ behaviour and welfare indicators

<p>Restriction of young rabbit females during rearing is a widespread management technique that could have negative consequences on their welfare and behaviour. In the present work, a total of 24 young rabbit females aged 9 wk were used to evaluate 3 rearing feeding programmes until first parturition: CAL, fed ad libitum with a control diet [C: 11.0 MJ digestible energy (DE) and 114 g digestible protein (DP) per kg dry matter (DM)]; CR, receiving the C diet restricted (140 g/d) from 12 wk of age; and F, fed ad libitum with a low energy/high fibre diet [F: 8.7 MJ DE and 88 g DP per kg DM]. F females presented lower body weight than CAL and CR females at week 18 (–0.4 kg and –0.2 kg; P&lt;0.05), but differences in body weight disappeared at parturition. Feeding programme affected the daily feed intake of young females during rearing and gestation periods (on av. of 2 periods: 140, 127 and 179 g DM/d, for CAL, CR and F females, respectively; P&lt;0.001). Blood levels of glucose and insulin decreased with the age of rabbits (from 97 to 73 mg/dL for glucose and from 11 to 6 μUI/mL for insulin at 13 and 20 wk, respectively; P&lt;0.001). Concentration of non-esterified fatty acids was higher in the blood of CAL females (+0.13 mmol/L compared to F; P&lt;0.05), while corticosterone was higher in F females (+0.7 μg/dL compared to CAL; P&lt;0.05). The type of feeding schedule affected the lying still and eating behaviour (P&lt;0.01) of CR females, especially before and after feeding supply, as well as their behavioural stressed indicators (stereotypies; P&lt;0.01), which were more frequent in CR females before feeding supply at 20 weeks of age. Therefore, ad libitum use of a low energy/high fibre diet is an adequate feeding programme for young rabbit females, which does not alter their behavioural patterns.</p>

Hormonal and behavioral changes induced by acute and chronic experimental infestation with Psoroptes cuniculi in the domestic rabbit Oryctolagus cuniculus

Background

Parasitic diseases are important in animal production because they cause high economic losses. Affected animals often exhibit stereotypical behavioral alterations such as anorexia and inactivity, among others. Among the diseases that commonly affect domestic rabbits is mange, which is caused by the mite Psoroptes cuniculi. Therefore, within the context of the host-parasite relationship, it is critical to understand the mechanisms involved in the alteration of host behavior, in order to better utilize sick animal behavior as a strategy for diagnosis and treatment of disease.

Methods

Rabbits were infested placing mites in the ear conduct. We characterized changes in exploratory behavior and scent marking evoked by acute (1-9 days) and chronic (25-33 days) experimental infestation. Behavior was recorded during ten minutes while the animals were in a 120 cm × 120 cm open field arena divided into 9 squares. Serum cortisol was measured individually using radioimmunoassay kits. Locomotor activity, chinning, rearing and body weight were compared using a Friedman test, the effect of treatment (infested versus non-infested) across time was analyzed using a repeated measures ANOVA, and the Pearson test was used to determine whether chinning and ambulation scores were significantly correlated. Serum cortisol levels and food consumption were analyzed with a Kruskal-Wallis test and body temperature was analyzed with an ANOVA test.

Results

We observed a significant decrease in rearing behavior as early as two days post-infestation, while chinning and locomotor activity were significantly decreased four days post-infestation. Chronic infestation was associated with decreased food intake, significant weight loss, and a trend toward increased serum cortisol levels, while no changes were observed in body temperature.

Conclusions

The presence of visible lesions within the ear canal is commonly used to detect mite infestation in rabbits, but this is possible only after chronic infestation. The behaviors described here may be a useful and economic tool in guiding the early diagnosis of parasitic infestation by P. cuniculi, allowing for early treatment and the application of control measures before significant weight loss occurs, thereby avoiding economic losses.

Novel food items as environmental enrichment for rodents and rabbits

This column discusses the use of novel dietary supplements as environmental enrichment for rodents and rabbits. The purpose of enrichment is to encourage behaviors that are appropriate for a particular species and that satisfy an animal's physical and psychological needs.

Environmental enrichment for laboratory rodents and rabbits: requirements of rodents, rabbits, and research

Environmental conditions such as housing and husbandry have a major impact on the laboratory animal throughout its life and will thereby influence the outcome of animal experiments. However, housing systems for laboratory animals have often been designed on the basis of economic and ergonomic aspects. One possible way to improve the living conditions of laboratory animals is to provide opportunities for the animals to perform a species-specific behavioral repertoire. Environmental enrichment should be regarded both as an essential component of the overall animal care program and equally important as nutrition and veterinary care. The key component of an enrichment program is the animal staff, whose members must be motivated and educated. It is critically important to evaluate environmental enrichment in terms of the benefit to the animal by assessing the use of and preference for a certain enrichment, the effect on behavior and the performance of species-typical behavior, and the effect on physiological parameters. At the same time, it is necessary to evaluate the impact on scientific outcome, how the enrichment influences the scientific study, and whether and how the statistical power is affected. The result will depend on the parameter measured, the type of enrichment used, and the animal strain. In this article, goals of enrichment are defined and discussed. Animal behaviors and needs are described, along with the translation of those needs into environmental enrichment programs. Specific types of environmental enrichment are outlined with examples from the literature, and an evaluation of environmental enrichment is provided.

Preference of guinea pigs for bedding materials: wood shavings versus paper cutting sheet

The preference of guinea pigs for bedding materials, wood shavings (WS) or paper cutting sheets (PS), was studied. Animals aged 8 weeks and 20 weeks showed a similar behaviour pattern during 30 min in the light, preferring WS to PS regardless of ages. Over both light and dark periods for 24 h, guinea pigs apparently preferred WS in the light, spending much more time resting in them than in PS. In the dark, the border-crossing was significantly more frequent than in the light, and the staying time was rather longer in PS than WS. The results suggest that guinea pigs prefer different bedding materials under light and dark conditions.

Wire-Floor Pens as an Alternative to Metallic Cages in Fattening Rabbits: Influence on Some Welfare Traits

The possibility of improving the welfare of fattening rabbits by rearing them in pens instead of cages was investigated. Time budgets, locomotion, ear lesions, breaking strength of the femur and productivity were compared in fattening rabbits kept at the same stocking density (15 rabbits m−2) either in standard cages of 0.4m2 (6 animals) or in pens of 1.6m2 (24 animals). Behavioural observations, performed by video recording at 6 and 9 weeks of age, indicated that the frequency of rabbits walking over one another was higher in cages than in pens at 9 weeks of age. Although the time spent in locomotion did not differ significantly, the number of consecutive hops performed by animals was clearly increased in pens at 6 weeks and tended to be higher at 9 weeks. In pens (without a ceiling), rabbits were observed ‘keeping watch’ with a characteristic fully upright posture; this was not possible for rabbits in cages (with ceilings at 30cm).

Ear lesions were more frequent in caged rabbits than in penned; this might be due to the caged rabbits walking on one another, due to the lack of space to perform locomotory behaviour. Weight, diameter and breaking strength of femur tended to increase in rabbits kept in pens. In penned rabbits, body and carcase weight were significantly reduced (by 2.0% and 3.4% respectively) when compared with caged ones. However, overall, the use of wire-floor pens of 1.6m2, housing 24 animals, was considered to be beneficial to fattening rabbits’ welfare when compared to standard-sized cages holding 6 animals.