Fibres in rabbit feeding for digestive troubles prevention: respective role of low-digested and digestible fibre

A review on the interactions between gut microflora and digestive mucosal immunity. Possible ways to improve the health of rabbits

Feedstuff tables are presentad including the composition and the nutritive value of 53 raw materials used in compound diets for intensively reared rabbits. Each raw material is characterised by 23 analytical data and its digestible protein and energy values. Because of the importance of the fibre fractions in the nutrition of the rabbit, special efforts have been done to characterise the carbohydrate complex. The digestibility data were selected after a compilation of original literatura data and a discussion between the authors. The methodology used, in the different in vivo assays, was evaluated accurately in order to judge the reliability of the data. Besides digestible and metabolisable energy values are also presentad because they lead to a better mutual comparison between raw materials for formulation purposes. Finally, attention has been drawn that the presentad nutritiva values fit well with the proposed nutrient composition and show coherence in each category of feedstuffs.

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Nutritive value of raw materials for rabbits: Egran tables 2002.

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.

Feed intake limitation strategies for the growing rabbit: effect on feeding behaviour, welfare, performance, digestive physiology and health: a review.

A 3 to 4 week feed restriction of about 20% to 25% of the free intake is widely applied in rabbit breeding systems to reduce post-weaning digestive disorders. However, a short intensive feed restriction is described in few studies and can be beneficial for growing rabbits due to a longer re-alimentation period. The aim of this study was to evaluate the effect of ad libitum (AL) and two restriction levels of feeding (50 and 65 g/rabbit per day) applied for 1 week on performance, gastrointestinal morphology and physiological parameters during the restriction and during the re-alimentation period. Rabbits were divided into three experimental groups: AL rabbits were fed AL, R1 rabbits were restricted from 42 to 49 days of age and received 50 g daily (29% of AL) and R2 rabbits were restricted at the same age and were fed 65 g of feed daily (37% of AL). In the 1(st) week after weaning and in the weeks after restriction, all the groups were fed AL. During the restriction period, daily weight gain (DWG) in R1 significantly dropped to 11% (experiment 1) and 5% (experiment 2) compared with rabbits in the AL group, although they were fed 29% of AL, whereas in the R2 group it decreased to 20% (experiment 1) and 10% (experiment 2). In the week following feed restriction, DWG in the restricted groups increased (P<0.001) to 166% and 148% in R1 and to 128% and 145% in R2. Restricted rabbits in both the experiments reached up to 90% to 93% of the final live weight (70 days) of the AL group. Over the entire experimental period, feed restriction significantly decreased feed intake to 85% to 88% of the AL group; however, the feed conversion ratio was lower (P<0.05) only in experiment 1 (-6% in R1 and -4% in R2). Digestibilities of CP and fat were not significantly higher during the restriction period and during the 1(st) week of re-alimentation compared with the AL group. Significant interactions between feeding regime and age revealed the shortest large intestine in the AL group at 49 days of age and the longest at 70 days in the AL and R1 groups. Small intestinal villi were significantly higher and the crypts were significantly deeper in the restricted groups. It could be concluded that short intensive feed restriction increased digestible area in the small and large intestines, including the height of villi and depth of crypts, which might be involved in the compensatory growth and defence mechanism.

The effect of 1-week feed restriction on performance, digestibility of nutrients and digestive system development in the growing rabbit.

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 (-4.5 g/% of restriction), but relatively moderate: the weight loss of the more-restricted rabbits (60%) reached 7.7% (-200 g) compared to the AL group. Over the whole fattening period, the feed restriction reduced linearly and significantly the feed conversion (FC) (-0.0077 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: -9% compared to AL). The morbidity was also significantly reduced (-6%) 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.

Feed restriction strategy in the growing rabbit. 2. Impact on digestive health, growth and carcass characteristics.

Protein replacement by digestible fibre in the diet of growing rabbits: 2-Impact on performances, digestive health and nitrogen output

Les performances et l'etat sanitaire ont ete etudies chez le lapin en croissance, en reponse a une reduction lineaire du taux de proteines MAT (regime T1=17,7; T2=16,4; T3=15,2 et T4= 13,9%), substituees par des fibres digestibles FD (18,5 a 22,1%). Au total 716 lapins par regime ont ete utilises dans une etude multi-site (n=7). Entre le sevrage et l'abattage, la croissance et l'ingestion ne different pas entre les regimes. Entre le sevrage et 49j. d'âge, la hausse du ratio FD/MAT conduit a une baisse lineaire de la vitesse de croissance (-4g/j de Tl a T4, P<0,001), associee a une baisse de la consommation (-5,7% de Tl a T4). L'accroissement du ratio FD/MAT au dela d'une valeur de 1,3 (T1+T2 vs T3+T4) reduit la mortalite par diarrhee (12,5 vs 7,8%; P<0,05) et l'index de risque sanitaire (20,7 vs 15,6%, P<0,05) entre le sevrage et l'abattage. Une reduction significative de la mortalite par EEL (1 site) est egalement observee lorsque le ratio FD/MAT est superieur a 1,3.

Effet d'une hausse du ratio fibres digestibles/protéines sur les performances zootechniques et l'état sanitaire du lapin en croissance: résultats préliminaires d'une étude multi-site

S. Montessuy

Papers

Feed restriction strategy in the growing rabbit. 2. Impact on digestive health, growth and carcass characteristics.

Protein replacement by digestible fibre in the diet of growing rabbits: 2-Impact on performances, digestive health and nitrogen output

Effet d'une hausse du ratio fibres digestibles/protéines sur les performances zootechniques et l'état sanitaire du lapin en croissance: résultats préliminaires d'une étude multi-site