This review aims to present the different effects produced by a post-weaning intake limitation strategy on the growing rabbit, now largely used by French professional rabbit breeders. Although a quantitative feed restriction leads to slower growth, feed conversion (FC) is improved, particularly when the rabbits are again fed freely, as compensatory growth occurs. This better FC or the healthy rabbit is because of better digestion resulting from slower passage through the intestine, whereas the digestive physiology is slightly modified (morphometry of the intestinal mucosa, fermentation pattern, microbiota). Meat quality and carcass characteristics are not greatly affected by feed restriction, except for a lower dressing-out percentage. One of the main advantages of limiting post-weaning intake of the rabbit is to reduce the mortality and morbidity rate due to digestive disorders (particularly epizootic rabbit enteropathy syndrome). The consequences for animal welfare are debatable, as feed restriction probably leads to hunger, but it reduces the incidence of digestive troubles after weaning. However, the growing rabbit adapts very well to an intake limitation strategy, without any aggressive behaviour for congener. In conclusion, restriction strategies could improve profitability of rabbit breeding, but they should be adapted to any specific breeding situation, according to the national market, feed prices, etc.

-The aim of this work was to determine the main factors that affect caecal pH, the caecal concentrations and molar proportions of volatile fatty acids (VFA) and the weight of caecal contents. The database was constituted of data (n = 92) from three laboratories that included the mentioned traits and the chemical composition and nutritive value of the diets. The laboratory affected caecal pH (P < 0.001) probably because of the differences in sampling time among them. Dietary uronic acids (UA) were measured in 21 diets and were negatively correlated with caecal pH and positively with caecal VFA concentration and the proportion of propionic acid (P = 0.004, 0.06 and 0.03, respectively). When UA was removed from the model, no other chemical characteristics significantly affected caecal pH, and digestible NDF was the variable which was the best correlated with it (R 2 = 0.58; P < 0.001). Only one laboratory detected a relationship between caecal pH and caecal concentrations of VFA (P = 0.044) and N-NH 3 (P = 0.14), which accounted for 12% of the variability observed in caecal pH. A linear and quadratic effect of dietary NDF and the degree of lignification of NDF on VFA concentration was found (R 2 = 0.56; P < 0.001), indicating a positive effect of high levels of low lignified fibre on caecal VFA. The weight of caecal contents was quadratically influenced by dietary NDF (R 2 = 0.39; P < 0.001). It was also linearly affected by the degree of lignification of NDF (P < 0.001). Dry matter intake was negatively correlated with caecal content weight (P < 0.001; R 2 = 0.44), once the effects of the laboratory and dietary digestible energy concentration were discounted. Résumé -Identification des principaux facteurs affectant les paramètres de fermentation dans le caecum chez les lapins en croissance. Cette étude avait pour but d'identifier les principaux facteurs qui affectent le pH, les concentrations et les proportions molaires en acides gras volatils (AGV) du contenu du caecum, ainsi que le poids du contenu caecal. Une base de données a été constituée à partir de résultats fournis par trois laboratoires (n = 92) comprenant, outre les paramètres caecaux, la composition chimique et la valeur nutritive des régimes. Le laboratoire a eu un effet (P < 0,001) sur le pH caecal en raison probablement de différences dans les temps de prélèvement. Les teneurs en acides uroniques (AU), qui ont été mesurées sur 21 régimes, ont été négativement corrélées avec le pH caecal et positivement corrélées avec la concentration en AGV et la proportion d'acide propionique (P = 0,004, 0,06 et 0,03, respectivement). En enlevant les AU du modèle, le pH caecal n'a été influencé par aucune autre composante chimique et la variable la plus étroitement corrélée a été la teneur en NDF digestible (R 2 = 0,58 ; P < 0,001). Un effet linéaire et quadratique du taux de NDF et du degré de lignification (R 2 = 0,56 ; P < 0,001) a été observé sur la concentration en AGV, indiquant un effet positif des taux élevés de fibres peu lignifiées sur les AGV da...

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A field enquiry mentioned the potential positive impact of a feed restriction on the health of young rabbits, but no objective information relates the intake to digestive health. The effects of a post-weaning feed restriction strategy were thus studied on digestive health and growth and carcass parameters of the growing rabbit, using a monofactorial design that produces a quantitative linear reduction of the intake, from ad libitum (AL group) to 80%, 70% and 60% of AL. The study was performed simultaneously in six experimental sites, on 1984 growing rabbits (496 per treatment) collectively caged from weaning (34 to 38 days of age, depending on the site) to slaughter (68 to 72 days). The feeding programme was applied as followed: restriction during 21 days after weaning, and then ad libitum till slaughter. During the feed restriction period the growth rate was linearly reduced with the restriction level, by 0.5 g/day for each percent of intake reduction. When returning to ad libitum intake (after 54 days old) a compensatory growth and a higher feed efficiency occurred. Therefore, the impact of the feeding programme on the slaughter weight (SW) was significant (24.5 g/% of restriction), but relatively moderate: the weight loss of the more-restricted rabbits (60%) reached 7.7% (2200 g) compared to the AL group. Over the whole fattening period, the feed restriction reduced linearly and significantly the feed conversion (FC) (20.0077 unit/% of restriction). Carcass traits were little affected by the feeding programme, except for a slightly lower decrease of the dressing percentage (mean: 1.2 units between AL and the three restricted groups). On the six experimental sites, mortality and morbidity were always caused by acute digestive disorders, namely diarrhoea and/or caecal impaction. Independent of the treatment, the mortality rate strongly varied according to the site (between 7% and 18% from weaning to 54 days and for the AL group). During feed restriction, the mortality was significantly lower from a restriction threshold of 80% (meanly: 29% compared to AL). The morbidity was also significantly reduced (26%) for the two most restricted groups (70% and 60%). The favourable effect of a lower intake on health did not persist after returning to ad libitum intake (54 days to slaughter), since mortality and morbidity were not significantly different among the treatments. Such a feeding strategy thus represents a double benefit in terms of feed costs and lower losses of young rabbits.

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 À1 full caecum of the total bacteria, Bacteroides-Prevotella

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The use of specific methods other than gravimetric ones to analyse fibre permitted a more precise study of the degradation of cell wall (CW) in the digestive tract. Digesta flow and rate of passage measurements have not been assessed previously in rabbits to investigate fibre digestion and fibre effects simultaneously in the proximal and in the distal segments of the tract. The effect of the level of dietary fibre on ileal and overall digestibility and rate of passage were studied by comparing semi-purified diets containing only one source of CW (dehydrated lucerne (Medicugo sativa) meal) given to adult female rabbits. The effect of fibre particle size and adaptation period were also investigated. Measurements of fibre composition using both colorimetric and gas-liquid chromatographic techniques, showed that large amounts of (CW) were degraded in the caecocolic segments. Increasing dietary fibre level reduced the rate of passage but fibre degradation was increased, at the same time a lower digestive efficiency for energy in the small intestine was found. A small quantity of CW was apparently degraded before the caecum, assuming that the water-soluble fraction of CW was essentially implicated. Grinding lucerne meal through a I mm instead of a 3 mm screen did not improve CW digestibility in spite of a longer rate of passage in the caeco-colic segments. Adaptation to a high-fibre diet resulted in an higher digestive volume for colon and caecum, related to an improved degradation of CW. Furthermore, digestive efficiency in the small intestine appeared higher for rabbits adapted to a high-fibre diet than that for rabbits initially fed on a low-fibre diet.Fibre: Digestion: Rate of passage: Rabbit Nutritional effects of dietary fibre in simple-stomached animals generally have been studied in the whole digestive tract of non herbivorous species (e.g. pigs and rats), using faecal digestibility or rate of passage measurements. More recently, there have been some reports on the effects of fibre on digestion in the small intestine of the pig (Fade1 et a/. 1989; Laplace et a/. 1989), but there are no known comparable studies in herbivorous simple-stomached animals (e.g. horse and rabbit). Furthermore, little information is presently available about fibre degradation using precise analytical methods rather than gravimetric methods (Longland et a/. 1989;Longstaff & McNab, 1989).Evidence for the effect of fibre composition on digestive phenomena was obtained in several studies (Graham e t a / . 1986;Gidenne, 1987), but no consistent results were obtained on the effect of the level of cell wall (CW) on diet digestion because mixed diets including various fibre sources were used. Also, frequently the particle sizes of CW were not considered in spite of their role in digestive processes and motility of the tract. In addition, particle size has a particular effect on caeco-colic motility of the rabbit , and fine particles are delayed in the colon and are brought back to the caecum during the hard faeces excretion phase, as shown by...

ABSTRACT:The aim of this paper was to draw up a set of recommendations for applied nutrition and feeding trials with rabbits, in relation to certain aspects such as determining the nutritive value of raw materials or diets in growing or reproducing animals, studying digestive physiology and obtaining growth and reproduction parameters. We deal first with animals, size of the sample, housing conditions, diets, handling, measurements, and the data analyses relevant to the design of the experiment are described. Secondly, we give a list of recommended items and include some comments.