Rabbit Caecum Research Articles

Ex vivo motility in the base of the rabbit caecum and its associated structures: an electrophysiological and spatiotemporal analysis.

We examined the coordination between contractile events at different sites in the basal portion of the rabbit caecum and its associated structures that were identified by electrophysiological recordings with simultaneous one-dimensional, and a novel two-dimensional, spatiotemporal mapping technique. The findings of this work provide evidence that the caecum and proximal colon/ampulla coli act reflexly to augment colonic outflow when the caecum is distended and mass peristalsis instituted, the action of the latter overriding the inherent rhythm and direction of haustral propagation in the adjacent portion of the proximal colon but not in the terminal ileum. Further, the findings suggest that the action of the sacculus rotundus may result from its distension with chyme by ileal peristalsis and that the subsequent propagation of contraction along the basal wall of the caecum towards the colon may be augmented by this local distension.

The complete mitochondrial genome of rabbit pinworm Passalurus ambiguus: genome characterization and phylogenetic analysis.

Passalurus ambiguus (Nematda: Oxyuridae) is a common pinworm which parasitizes in the caecum and colon of rabbits. Despite its significance as a pathogen, the epidemiology, genetics, systematics, and biology of this pinworm remain poorly understood. In the present study, we sequenced the complete mitochondrial (mt) genome of P. ambiguus. The circular mt genome is 14,023 bp in size and encodes of 36 genes, including 12 protein-coding, two ribosomal RNA, and 22 transfer RNA genes. The mt gene order of P. ambiguus is the same as that of Wellcomia siamensis, but distinct from that of Enterobius vermicularis. Phylogenetic analyses based on concatenated amino acid sequences of 12 protein-coding genes by Bayesian inference (BI) showed that P. ambiguus was more closely related to W. siamensis than to E. vermicularis. This mt genome provides novel genetic markers for studying the molecular epidemiology, population genetics, systematics of pinworm of animals and humans, and should have implications for the diagnosis, prevention, and control of passaluriasis in rabbits and other animals.

Assessing the possible interaction between Carduus marianus and dietary deoxynivalenol on caecal microbiota and fermentation of growing rabbits

Contamination of feed with mycotoxins is a common problem encountered in animal farming. Mycotoxin exposure can affect adversely the health of animals. In rabbits caecal fermentation is an essential digestive process being indication of physiological alterations. Deoxynivalenol (DON) is one of the most frequent contaminants of grains which affect the growth of monogastric animals. Data about dietary DON and its effect in rabbits are scarce. Medicinal plants are often used as feed additives to enhance the performance of the animals. Carduus marianus (milk thistle) is known for its hepatoprotective and antioxidant effects (among others) but no data are available about the effect on rabbit caecum. Considering the aforementioned, the aim of this study was to assess the possible interactive effect of Carduus marianus and DON on the caecum of growing rabbits. 75 Pannon White rabbits were reared for six weeks from 35 (after weaning) till 77 days of age. Rabbits received the following diets: control (C), control with DON (CT), control supplemented with C. marianus in 0,5% (H1), control supplemented with C. marianus in 0,5% and DON (H1T), control supplemented with C. marianus in 1% (H2) and control supplemented with C. marianus in 1% and DON (H2T). On slaughter, caecum was collected for the analysis of total volatile fatty acids (VFA) and the microbiota of the caecum, pH of the caecum was also recorded. There was no significant difference in total VFA concentration or individual VFA. Number of aerobic bacteria significantly differed among toxin and non-toxin groups. DON affected adversely the number of aerobic bacteria. An interactive effect of DON and Carduus marianus on E.coli number was observed. There was no effect on total or individual VFA amounts.

In Vitro Study and Comparison of Caecal Methanogenesis and Fermentation Pattern in the Brown Hare (Lepus europaeus) and Domestic Rabbit (Oryctolagus cuniculus)

The brown hare and the domestic rabbit are mid-sized herbivorous mammals and hindgut fermenters, though their digestive physiologies differ in some traits. The objective of this study was to estimate and compare the caecal microbial activity in hares and rabbits via an analysis of the following end-products of in vitro caecal fermentation: methane, total gas production, short chain fatty acids and ammonia concentration. Hare caecal methanogenesis occurred at a much lower level (0.25 mmol/kg for samples incubated without substrate and 0.22 mmol/kg for samples incubated with substrate) than that of the rabbit (15.49 and 11.73 mmol/kg, respectively) (P<0.001). The impact of the substrate’s presence on caecal methanogenesis was not significant, though its presence increased the total gas production during fermentation (P<0.001). Hare caecal microflora produced a lower short chain fatty acids concentration than did rabbit microorganisms (P<0.05). In unincubated hare samples, the short chain fatty acids concentration was 28.4 mmol/kg, whereas in unincubated rabbit samples, the short chain fatty acids concentration was 51.8 mmol/kg. The caecal fermentation pattern of the hare was characterised by higher propionate and isobutyrate molar proportions compared with those observed in rabbit caecum (P<0.01). No significant changes in the ammonia concentration in either rabbit or hare caecum were found. The results obtained indicate some differences in the activity of the microbial populations colonising the hare and rabbit caecum, particularly in regards to methanogenic Archaea.

Sequence variability in four mitochondrial genes among rabbit pinworm (Passalurus ambiguus) isolates from different localities in China

Passalurus ambiguus is a common pinworm which parasitizes in the caecum and colon of rabbits. This study examined genetic variability among P. ambiguus isolated from naturally infected rabbits in four different provinces in China. The partial mitochondrial (mt) cytochrome c oxidase subunit 1 (pcox1), cytochrome b (pcytb) and NADH dehydrogenase subunits 1 and 5 (pnad1 and pnad5) were amplified separately from individual nematodes by PCR and sequenced. The results showed that pcox1, pcytb, pnad1 and pnad5 were 714, 663, 645 and 546 bp in length, respectively. The intra-specific sequence variations within P. ambiguus were 0–1.1% for pcox1, 0–1.2% for pcytb, 0–0.6% for pnad1 and 0–1.3% for pnad5, whereas inter-specific sequence differences with other members of the Oxyuridae were 16.2–17.3% for pcox1, 27.8–30.4% for pcytb, 20.2–24.0% for pnad1 and 27.1–30.3% for pnad5. Phylogenetic analyses using Bayesian inference (BI), maximum likelihood (ML) and maximum parsimony (MP) methods, based on the combined sequences of the four partial mtDNA sequences, revealed that all the P. ambiguus samples form monophyletic groups. This study demonstrated the existence of low-level intra-specific variation in cox1, cytb, nad1 and nad5 genes among P. ambiguus isolates from different geographic regions in China, and these four mtDNA sequences can be used as genetic markers for the population genetic studies of P. ambiguus, as well as the differentiation of P. ambiguus from other oxyurid nematodes.

Effect of thyme oil on small intestine integrity and antioxidant status, phagocytic activity and gastrointestinal microbiota in rabbits

The effects of 0.5 g thyme oil per kg dry matter (DM) of diet on duodenal tissue integrity, antioxidant status, phagocytic activity and selected microbiota in the caecum and faeces of rabbits were studied. Twenty-four rabbits were divided into two groups and were fed a commercial granulated diet for growing rabbits (CD) with access to water ad libitum. The first group was fed the CD, while to the CD of the second group thyme oil was added. Intestinal integrity was tested by measuring the transepithelial electrical resistance (TEER). Thyme oil significantly increased the value of total antioxidant status (TAS) in the blood plasma and glutathione peroxidase (GPx) activity in the liver, and it decreased malondialdehyde (MDA) concentration in the duodenal tissue. Thyme oil resulted in strengthened intestinal integrity, as the essential oil supplementation significantly increased TEER values in the experiment. The faecal microbiota of rabbits was almost completely balanced in both groups, and only a slight decrease was found in the microbial population at day 42 of the trial. In both groups, the bacterial counts were generally lower in the caecum than in the faecal samples. In conclusion, dietary supplementation with 0.5 g/kg DM thyme oil may improve intestinal integrity, and it may have an antioxidant effect. A tendency was also found for thyme oil to stimulate the abundance of some microbes beneficial in the rabbit gut.

Comparative study of fermentation and methanogen community structure in the digestive tract of goats and rabbits

Methane is the most important anthropogenic contribution to climate change after carbon dioxide and represents a loss of feed energy for the animal, mainly for herbivorous species. However, our knowledge about the ecology of Archaea, the microbial group responsible for methane synthesis in the gut, is very poor. Moreover, it is well known that hindgut fermentation differs from rumen fermentation. The composition of archaeal communities in fermentation compartments of goats and rabbits were investigated using DGGE to generate fingerprints of archaeal 16S rRNA gene. Ruminal contents and faeces from five Murciano-Granadina goats and caecal contents of five commercial White New Zealand rabbits were compared. Diversity profile of methanogenic archaea was carried out by PCR-DGGE. Quantification of methanogenic archaea and the abundance relative to bacteria was determined by real-time PCR. Methanogenic archaeal species were relatively constant across species. Dendrogram from DGGE of the methanogen community showed one cluster for goat samples with two sub-clusters by type of sample (ruminal and faeces). In a second cluster, samples from rabbit were grouped. No differences were found either in richness or Shannon index as diversity indexes. Although the primer sets used was developed to investigate rumen methanogenic archaeal community, primers specificity did not affect the assessment of rabbit methanogen community structure. Rumen content showed the highest number or methanogenic archaea (log₁₀ 9.36), followed by faeces (log₁₀ 8.52) and showing rabbit caecum the lower values (log₁₀ 5.52). DGGE profile showed that pre-gastric and hindgut fermenters hold a very different methanogen community. Rabbits hold a microbial community of similar complexity than that in ruminants but less abundant, which agrees with the type of fermentation profile.

The &lt;i&gt;in vitro&lt;/i&gt; caecal fermentation of different starch sources in rabbits

The objective of our study was to extend the knowledge of microbial fermentation of starch in the rabbit caecum using the in vitro gas production technique. Different sources of starch (wheat and maize grain, raw and cooked potato) and different starch isolates (wheat, maize and potato starch) were incubated with inoculum, prepared from rabbit caecum content. The gas production parameters such as total potential gas production (parameter “B”), gas production till 10 h of incubation (Gas10), maximum fermentation rate (MFR) and time of maximum fermentation rate (TMFR) were estimated with Gompertz model and were significantly affected by the substrata. Differences between maize grain and maize starch were small: MFR and TMFR were not different, while Gas10 of maize starch was higher than from maize grain (5 and 3 ml/kg DM, respectively; P &lt; 0.05). MFR of wheat starch was higher than that of wheat grain (3.1 and 2.4 ml/h, respectively; P &lt; 0.05), but reached maximum rate later (TMFR: 12.4 and 10.9 h, respectively; P &lt; 0.05) and had lower Gas10 (6 and 9 ml/kg DM, respectively; P &lt; 0.05). The fermentation of cooked potato reached the TMFR after 8.5 h of incubation and had the highest MFR (2.9 ml/h) and Gas10 (16 ml/kg DM) of all substrata. The MFRs of raw potato and potato starch were similar (2.1 and 2.3 ml/h, respectively), although TMFR and Gas10 of raw potato were shorter and higher than those of potato starch (TMFR of 10.7 and 17.2 h and Gas10 of 10 and 1 ml/kg DM, respectively; P &lt; 0.05).

Intestinal microbial community diversity between healthy and orally infected rabbit with Entamoeba histolytica by ERIC-PCR

Enterobacterial repetitive intergenic consensus (ERIC)-PCR was applied to analyze the difference of intestinal microbial community diversity between healthy and orally infected rabbits with Entamoeba histolytica. The dynamic changes in different parts of digestive system including the duodenum, jejunum, ileum, caecum, and rectum in healthy and infected rabbits at different time points were also tested. The intestinal microbial community of the control healthy rabbits was steady, and the total number of ERIC-PCR bands in the control healthy rabbit was the least in the rectum and the most in the caecum. ERIC-PCR bands of orally inoculated rabbits did not obviously change until 24 h after postinoculation (p.i.). The numbers of the ERIC-PCR bands gradually decreased from 24 to 72 h p.i., and then, with the development of disease, the band numbers gradually increased until 6 days p.i. Sequence analysis showed that the nucleotide sequence homologies of the fragment about 1,200 bp of infected ileum sampled at 32 h p.i. were above 95 % with Sinorhizobium meliloti enterobacterial, Erwinia amylovora and Salmonella typhimurium, and the nucleotide sequence homologies of the fragment about 300 bp of infected ileum sampled at 48 h p.i. were more than 90 % with Xanthomonas campestris enterobacterial, Yersinia enterocolitica subsp., Shigella flexneri, S. meliloti enterobacterial, Yersinia pestis, Klebsiella pneumoniae subsp., and Escherichia coli. The prominent bacteria had changed after E. histolytica infection. The DNAstar of staple of ERIC-PCR showed that aerobe and facultative aerobe (E. coli, Shigella, and Salmonella) became preponderant bacilli in the intestine of orally infected rabbits with E. histolytica.

Effect of oxidation state of dietary sunflower oil and dietary zinc and α -tocopheryl acetate supplementation on performance of fattening rabbits

Twelve diets were formulated using the same raw materials and including 3% of sunflower oil at 3 different oxidation levels [fresh (F), peroxidised (P; 55oC for 11 d; 83 meq O 2 /kg oil) and highly-oxidised (O; 140oC for 31 h; ρ-anisidine value of 125)], with 2 levels of α-tocopherol supplementation (0 and 100 ppm), and 2 levels of Zn supplementation (0 and 200 ppm). A growing trial with 900 twenty eight d old rabbits was carried out in order to study the effect of the oxidation and protection level of supplemented oil on the performance of animals from weaning (28d) to 63 d of age. Another coetaneous trial was performed to study the effect of the oxidation level of sunflower oil (F, P and O) on caecal activity around weaning, using 120 suckling rabbits randomly re-allocated into 12 litters of 10 kits (4 litters per diet) from 17 to 44 d of age. Four rabbits per litter were slaughtered at 30 and 44 d (16 rabbits/treatment and age). Full gastro-intestinal tract and caecum were weighed and pH, dry matter (DM), ammonia nitrogen (NH 3 ) and volatile fatty acids concentration (VFA) values in caecal content were measured. No effect was observed either in the mortality rate, body weight gain, feed intake or conversion rate throughout the growing period when peroxidised or oxidised oils were included in the diet, being on average 32%, 45.1 g/d, 107.6 g DM/d and 2.44, respectively. Dietary supplementation with α-tocopherol and/or Zn had no effect on the mortality rate, feed intake and performance of rabbits during the fattening period. Daily weight gain just after weaning (28 to 30 d of age) was higher for kits receiving the diet supplemented with F and O diets than those with the P diet (55, 50 and 35 g/d, respectively; P <0.05), but no further effect on performance was observed. Young rabbits fed with the P diet showed lower DM percentage in caecum at 30 d of age (-9.5%; P <0.05) than those with F or O diets. Caecum of young rabbits fed with the O diet presented lower NH 3 content at 30 d of age that those given F diet (-38%; P <0.05) and higher total VFA and acetic acid concentration (+36 and +34 %, respectively; P <0.05). Therefore, and although many questions are still open, oxidised oils could be considered as a possible energy source for rabbit nutrition.

Spatiotemporal mapping of ex vivo motility in the caecum of the rabbit

We used high definition radial, strain rate and intensity spatiotemporal mapping to quantify contractile movements of the body and associated structures of the rabbit caecum when the terminal ileum was being perfused with saline at a constant rate. This perfusion caused gradual distension of the caecum as a result of relative restriction of outflow from the ampulla caecalis. The body of the caecum exhibited two patterns of motility that appeared autonomous, i.e. occurred independently of any contractile activity at the inlet or outlet. Firstly, the pattern that we termed ladder activity consisted of an orderly sequential contraction of bundles of axially oriented circular muscle between the spiral turns of longitudinal muscle and proceeded either from base to tip or from tip to base at a similar frequency and velocity. Secondly, less-localised, rapidly propagating synchronous contractions of both circular and longitudinal muscle, which were more common when the caecum was distended, that were termed mass peristalsis. Movements of the ileum and sacculus rotundus occurred at the same frequency and were broadly coordinated. Distension of the distal sacculus occurred synchronously with contraction of the ileum and did not propagate in an orderly manner across the structure, i.e. was instantaneous. This pattern was consistent with hydrostatic distension. Contractions propagated through the ampulla caecalis in either an orad or an aborad direction at a similar frequency to, and broadly correlated with, those in the ileum. The frequencies of distension of the sacculus and of contraction in the ileum and ampulla were momentarily augmented during mass peristalsis. The authors conclude that there was some coordination between the contractile activity of the terminal ileum and the caecal ampulla during periods of ongoing inflow from the ileum and between these structures and the caecum during mass peristalsis.

Immunohistochemical localisation of EGF receptors in the intestinal tract of growing rabbits in relation to age

Summary During postnatal development, the intestinal tract of newborns is exposed to morphological and functional alterations. Adaptive changes are being modulated to a great extent by biologically active substances secreted from milk, such as the epidermal growth factor (EGF). The aim of the present study was to establish by a comparative approach the distribution of receptors for EGF (EGFR and ErbB-1) expressed in epithelial cells lining the villi, crypts and serosa of the duodenum, ileum, caecum and colon of rabbits euthanised at the 21st (group A) and the 35th (group B) postnatal days. The intensity of immunohistochemical staining against EGFR on the villi surface in group A was higher than that of group B in the duodenum (2.8 ± 0.11 vs. 2.0 ± 0.17; P The EGFR reaction occurred in a narrow range of intensities in the crypts of all investigated segments of the intestines (0.9–1.2). In general, the lowest (0.7 ± 0.14) reaction was established in the serosa of the colon of 21-day-old animals. The age-dependent presence of EGFR observed indicated that this factor should be considered when defining the optimal weaning age of the rabbit.

Postnatal development of the rabbit caecal microbiota composition and activity

This study describes the development of the rabbit caecum microbiota and its metabolic activities from the neonatal (day 2) until the subadult period (day 70). The caecal microbiota was analysed using 16S rRNA gene approaches coupled with capillary electrophoresis single-stranded conformation polymorphism (CE-SSCP) and qPCR. At day 2, rabbits harboured population levels up to 8.4, 7.2 and 7.4 log(10) copy number g(-1) full caecum of the total bacteria, Bacteroides-Prevotella and Firmicutes groups, respectively. These populations reached their maximum levels from day 14 for Firmicutes groups (10.8 log(10) copy number g(-1) caecal content) and day 21 (11.4 and 10.7 log(10) copy number g(-1) caecal content of the total bacteria and the Bacteroides-Prevotella group, respectively). The archaeal population could be detected only from day 7 onwards (5.5 log(10) copy number g(-1) full caecum) and reached its maximum level at day 35 (7.4 log(10) copy number g(-1) caecal content). Similarity analysis, diversity calculation and quantitative evaluation of the stability of bacterial community CE-SSCP profiles provided some evidence that the caecal microbiota develops progressively from a simple and unstable community after birth into a complex and climax community in subadult rabbits. Meanwhile, the microbial activity evolved with the progressive decrease of the propionate/butyrate ratio towards a rabbit-specific value <1.

The effect of Linola and W92/72 transgenic flax seeds on the rabbit caecal fermentation - in vitro study

The effect of W92/72 transgenic flax seeds taken from a variety of Linola on the production of SCFA, ammonia and methane by bacteria inhabiting rabbit caecum was studied. The in vitro method was used where caecal contents from rabbits was incubated with W92/72 transgenic or Linola flax seeds, or without any additives (control samples). The total concentration of SCFA was higher in samples with the addition of flax seeds than in the control samples. The increase in concentrations of acetic, propionic and butyric acids was the highest in samples with Linola seeds added. A higher percentage of propionic and butyric acids was observed in the contents incubated with addition of flax seeds as compared to the control samples. This increase was the result of a percentage decrease in acetic acid. No differences were observed in the concentration of ammonia between fermented samples. Moreover, the addition of flax seeds resulted in slight decrease of pH in incubated samples. In gas samples, the methane level was higher in samples with flax seeds added, although the highest level was found in samples with transgenic seeds. In addition, gas pressure was significantly higher in samples with flax seeds added as compared to control samples, and this may indicate a higher intensity of microbiological fermentation processes. These studies suggest that neither Linola nor W92/72 flax seeds have any unfavorable effect on the caecal microflora activity of rabbits. A beneficial influence of flax seeds on the microbiological fermentation process in rabbit caecum was observed, based on an increase in percentage ratio of propionic acid in samples with flax seeds added.

Rapid adaptation of the bacterial community in the growing rabbit caecum after a change in dietary fibre supply

This work aimed to study the response of the growing rabbit caecal ecosystem (bacterial community and caecal environmental parameters) after a switch from a control to a low-fibre diet (LFD). A group of 160 rabbits were fed ad libitum a control diet (ADF: 20.4%) from weaning (36 days). At 49 days of age (day 0), 75 rabbits were switched to a LFD group (ADF: 10.7%), whereas 85 others (control group) remained on the control diet, for 39 days. Caecal contents were regularly sampled throughout the trial (60 rabbits per group). The bacterial community structure was characterized using CE-SSCP (capillary electrophoresis single strand conformation polymorphism) and total bacteria were quantified using real-time PCR. Redox potential (Eh), pH, NH3-N, volatile fatty acid (VFA) were measured in the caecum to characterize environmental parameters. The reduction of fibre in the diet modified the CE-SSCP profiles (P < 0.001) but not the diversity index (5.6 ± 0.8, ns). The number of 16S rRNA gene copies of total bacteria decreased (P < 0.01) in LFD rabbits compared with controls. In LFD rabbits, the caecal environment was less acid (+0.2 units; P < 0.01), more reductive (−11 mV; P < 0.05) and drier (+3.4 g 100 per g; P < 0.001), with an increase in NH3-N (+77%; P < 0.001) and a decrease in total VFA concentration (−17%; P < 0.001). We found significant correlations between the bacterial community, the quantity of bacteria and the caecal traits of the caecal ecosystem. Indeed, in both groups, the caecal traits barely constrained the total inertia of the CE-SSCP profile set (less than 14%), whereas total bacteria were positively related to total VFA, acetic acid and butyric acid levels, and Eh, and negatively related to pH. All the microbial and environmental modifications had occurred by day 2 and remained stable thereafter. These results suggest that the bacterial community in the growing rabbit caecum is able to adapt quickly after a change to in the dietary fibre supply to reach a new steady-state equilibrium.

Molecular profiling and identification of methanogenic archaeal species from rabbit caecum

During a comparison of 16S rDNA PCR-denaturant gradient gel electrophoresis (DGGE) profiles of methanogenic archaea from rumen fluid, rabbit caecum and pig feces, a unique band common to all rabbit caecum samples was observed. DGGE profiling also showed that the methanogen community from the New Zealand White adult rabbits is different and less complex than the methanogen communities from the rumen and pig feces. Small subunit ribosomal gene sequences of methanogenic archaea were subsequently retrieved from the constructed rabbit caecum 16S rDNA gene library. Results of the phylogenetic analysis indicated that rabbit caecum is inhabited by members of the genus Methanobrevibacter and is possibly one-species dominated, because all the retrieved sequences exhibited similarity values of 99% or higher. This species may well be a novel species of the genus Methanobrevibacter. It belongs to a distinct phylogenetic group containing Methanobrevibacter woesei, Methanobrevibacter thaueri and Methanobrevibacter gottschalkii strains isolated from animal feces, and Methanobrevibacter smithii from the predominating methanogen population of the human large bowel.

A new method to measure the redox potential (Eh) in rabbit caecum: relationship with pH and fermentation pattern

This study aimed to assess the anaerobic status of the caecal biotope in the rabbit through the measurement of its redox potential (Eh). Since the caecal content has a high viscosity, the duration of the Eh measurement is high (10 to 20 min) and two methods were compared in 10 week- old rabbits: in vivo vs. post-mortem. In addition, Eh, pH and temperature of the caecal digesta were analysed according to caecotrophy and three periods in the day (soft faeces production: 08:00-10:00 h and 12:00-14:00 h; hard faeces production: 17:00-19:00 h) were compared, using 34 rabbits aged 65 d and weighing 2.3 kg. Caecal Eh decreased 2 min after measurement began, and then stabilised from 20 min onwards (from −152 to 221 mV, P<0.001), in contrast to caecal pH which remained constant over time. Mean values for Eh (at 20 min) and pH were - 219 mV and 6.2 respectively, and did not change according to method or collection period. Only the caecal temperature was 2°C higher (P<0.001) for the in vivo (39°C) than for the post-mortem (37°C) method. Average caecal dry matter and total volatile fatty acid were on average 22 % and 106 mmol/L, and were affected neither by the method nor by the collection period. Caecal Eh was negatively correlated to caecal pH (R²=0.22; P=0.006, n=34), but not to other biotope traits. The Eh measurement in rabbit caecal content could be performed with a minimum recommended duration of 20 min, under anaesthesia or post-mortem. We confi rmed that the rabbit caecal ecosystem is highly anaerobic.

Degradation of dietary oligofructose and inulin in the gastro-intestinal tract of the rabbit and the effects on caecal pH and volatile fatty acids.

Three experimental fattening diets were each fed ad libitum to 12 animals of 8-9 weeks of age (initial weight 2,257 ± 87 g). The diets contained 0% (Control), 2% oligofructose (OF) (Raftifeed®OPS) or 2% inulin (Raftifeed®IPS). After an adaptation period of 10 days, the individually caged rabbits received the same diets with Cr2O3 as a marker. For the 24 h before they were euthanised (between 08:30 and 09:00), rabbits wore a plastic collar to prevent caecotrophy. Dietary treatment affected gut acidity only in the caecum where a tendency to a reduced pH in the inulin-fed rabbits was observed. The total caecal concentration of volatile fatty acids was similar among dietary treatments but a significant (P<0.05) change occurred in inulin-fed rabbits with an increase of butyrate proportion (17.6, 20.2 and 22.6% for control, OF and inulin rabbits, respectively) at the expense of acetate (75.0, 72.3 and 70.1%, respectively). Fructans were not detected in the ileum, caecum or faeces of control rabbits, indicating that both types of oligosaccharides originating from the raw materials were degraded quickly. Significant amounts of the b(2-1)-fructans were still present in the ileum content of both OF and inulin fed rabbits (1.78 and 1.63% DM). Apparent ileal digestibility of fructans was 100% in control rabbits but significantly lower (P<0.01) in OF (35.3%) and inulin (49.2%) fed rabbits. The absence of fructans from caecal and faecal samples confirms their complete fermentation by the caecal microbial flora. However, with the methodology used (which increased variability) and the limited number of replicates (4 pooled samples/diet), no significant difference in the degradation due to the chain length of the inuline-type fructans was detected.

In vitro fermentation of different commercially available pectins using inoculum from rabbit caecum

In vitro gas production kinetics of eight different commercially available pectin isolates from apple (4), citrus (2) and sugar beet (2), with a degree of methyl esterification (DMet) ranging from 9 to 73%, were determined twice using the mixture of caecum contents of two rabbits of 78 d of age per repetition as inoculum. The cumulated gas production over 60 h of incubation was modelled with the Gompertz model and the estimated and calculated kinetic parameters of each substrate compared. Total potential gas production (B), gas production till 10 h of incubation, maximum fermentation rate (MFR) and time of maximum fermentation rate (TMFR) were affected (P

Functional, Anatomical and Histological Development of Caecum in Rabbits

Functional, Anatomical and Histological Development of Caecum in Rabbits