Role of soluble fibre in diets for growing rabbits: a review

In this review, the methods to measure fibre and soluble fibre fractions have been briefly presented; we have referred to soluble fibre as the difference between Total Dietary Fibre (TDF) and Neutral Detergent Fibre (NDF) due to its simplicity to be obtained and the numerous studies that measured it; the effects of soluble fibre on performance, digestive efficiency and physiology, caecal activity and health of growing rabbits have been reviewed by a meta-analysis of studies available in literature, also with the aim of elucidating the relationships with other dietary nutrients. The level of soluble fibre affects the digestive utilizations of soluble and insoluble fibre fractions at ileum and caecum, ileal and caecal microbiota and caecal fermentations by modifying the amount and the type of substrate reaching the caecum. The increase of soluble fibre has a positive effect on the reduction of mortality in growing rabbits affected by epizootic rabbit enteropathy, which could be related to the high fermentability of soluble fibre, the changes exerted in the intestinal microbiota, and an enhanced gut barrier function just after weaning. A minimal supply around 12% of soluble fibre (as fed) is recommended in diets for postweaning and growing rabbits containing about 30% NDF and 18% ADF. These conclusions are linked to the use of sugar beet pulp as primary source of soluble fibre and should be confirmed with other soluble fibre sources

Effect of the increase of dietary starch and soluble fibre on digestive efficiency and growth performance of meat rabbits

Effect of increasing dietary starch and soluble fibre on performance and digestive efficiency was studied in 246 cross-bred rabbits from weaning (34 d of age) to slaughtering (75 d). A 3 72 factorial arrangement (i.e. three levels of starch: 60, 103, and 147 g/kg diet; two levels of soluble fibre: 100 and 138 g/kg diet) was used. The rabbits were assigned to six groups and fed the six diets ad libitum. When dietary starch was increased, the coefficient of total tract apparent digestibility (CTTAD) of dry matter (on average, 0.547\u20130.629) and all nutrients linearly increased (P<0.001), but the CTTAD of soluble fibre did not vary. Weight gain, digestible energy intake, and feed conversion ratio linearly (P<0.01) improved (6.4%, 5.7% and 11.1%, respectively), and feed intake decreased (5.6%). In the caecum, ammonia-N production linearly decreased (7.21\u20134.93 mmol/L; P=0.01), acetate proportion tended to increase (84.2\u201385.8 mmol/100mmol volatile fatty acids, VFA; P=0.06), and propionate value decreased (4.00\u20133.33 mmol/100mmol VFA; P<0.01). As the starch level increased, the CTTAD of NDF and hemicelluloses improved slightly in the diets with 100 g/kg soluble fibre, while at a higher rate in the diets with 138 g/kg soluble fibre (significant interaction, P<0.01). The increase of dietary starch linearly increased slaughter weight (SW) and carcass weight; the proportion of the gastrointestinal tract linearly decreased (196\u2013182 g/kg SW; P<0.001) and the dressing percentage increased (59.3\u201360.8% SW, P<0.001), as well as dissectible fat (P=0.03). The increase of dietary soluble fibre improved (P<0.001) the CTTAD of dry matter (0.540\u20130.639) and all nutrients, but the CTTAD of crude protein was not affected; it stimulated daily growth (5.3%; P=0.05) and reduced (P<0.001) feed intake (12.4%) and feed conversion ratio (15.0%). In the caecum, pH decreased (5.88\u20135.70; P=0.02), total VFA concentration tended to increase (73.8\u201382.8 mmol/L; P=0.10), and valerate concentration decreased (0.43\u20130.35 mmol/100mmol VFA; P=0.01). Slaughter weight and reference carcass weight increased (0.03<P<0.07); the gastro-intestinal tract proportion tended to increase (185\u2013190 g/kg SW; P=0.06) without affecting dressing percentage or carcass composition. In conclusion, the use of soluble fibre is recommended in association with (rather than in replacement of) starch to increase the energy value of diets and improve overall farm-feed efficiency and carcass quality

Aumento del nivel de fibra soluble y almid\uf3n en dietas para conejos en crecimiento: efectos sobre la eficacia alimenticia y los rendimentos productivos

From 34 d of age until slaughtering (75 d), 246 hybrid rabbits were divided into six experimental groups and fed six diets ad libitum, according to a bi-factorial arrangement with three levels of starch (6.0%, 10.3%, and 14.7%) and two levels of soluble fibre (10.0% and 13.8%). When dietary starch was increased, the apparent digestibility of DM (54.7 to 62.9%) and all nutrients linearly increased (P<0.001). Weight gain and feed conversion linearly (P<0.001) improved (6.4% and 11.1%, respectively), and feed intake decreased (5.6%). A significant interaction (P=0.05) was observed for NDF digestibility: as the starch level increased, NDF digestibility improved less in the diets with 10.0% soluble fibre than in the diets with 13.8% soluble fibre. The increase of dietary soluble fibre improved (P<0.001) DM digestibility (54.0 to 63.9%) and daily growth (by 5.3%; P=0.05) and reduced feed intake and feed conversion (by 12.4% and 15.0%, respectively; P<0.001). In conclusion, the use of soluble fibre is recommended in association with, rather than in replacement of, starch to increase the energy value of diets and improve overall farm-feed efficiency

Prediction of the nutritional value of European compound feeds for rabbits by chemical components and in vitro analysis

Chemical composition and in vitro analyses were used to predict the nutritional value of 164 experimental rabbit diets evaluated in six European Laboratories under standardised conditions. The equations were mainly developed by stepwise regression analysis with over two third of the samples (111) used as calibration set. The other third (53) was used as validation set, and a study of the residues was undertaken to calculate the error of validation. Twenty three different equations have been proposed to predict the nutritional value (mainly gross energy digestibility, GEd; and digestible energy, DE) of rabbit diets, as a function of the vailable variables. Acid detergent fibre (ADFom) was the chemical variable most closely related to GEd and DE (R2 = 0.49 and 0.43, respectively, RSD = 0.033 and 0.62, for GEd and DE, respectively), but the in vitro DM digestibility (DMdinv) predicted the energy value with greater accuracy (R2 = 0.7, 0.52, for GEd and DE, respectively) and lower standard error (RSD = 0.025, 0.58 for GEd and DE, respectively). The latter equations were improved (R2 = 0.81, 0.74 for GEd and DE, respectively) when ether extract (EE) and Lignin (sa)were included. The use of additive equations that predict the DE from the main constituents that supply energy (protein, ether extract and carbohydrates) did not increase the precision, nor decrease the validation error respect to the simplest ones. Digestible Energy was predicted with a similar accuracy and validation errors than GEd. Crude protein digestibility (CPd) was better predicted from chemical analysis (Lignin (sa), R2 = 0.49) than for DMdinv. The further inclusion of CP slightly increased its coefficient of determination (0.53). The error of validation was relatively low (0.050 as average) and of the same magnitude than the RSD of the equations

Dietary supplementation with mannanoligosaccharides and \u3b2-glucans in growing rabbits. 1. Growth performance, health status and carcass traits

A total of 384 rabbits weaned at 32 d of age were assigned to six experimental groups of 64 rabbits each, homogeneous in live weight (average and variability) and housed in individual cages. Animals fed ad libitum until slaughter (75 d) six diets which differed for the type and level of the supplemented additive: diet C without additives; diets G1 and G2 supplemented with two levels of \u3b2-glucans from Saccharomices cerevisiae (100 and 200 mg/kg, respectively); diets M1 and M2 supplemented with mannanoligosaccharides (Actigen, Alltech; 400 and 800 mg/kg, respectively); and diet GM (100 mg \u3b2-glucans + 400 mg mannanoligosaccharides/kg). Health status of animals was good (average mortality 3.5%) and both caecal fermentation traits and nutrient apparent digestibility were not affected by the inclusion level and type of additive. Growth performance of rabbits was not affected by the treatments, but daily weight gain (55.6 vs. 55.2 g/d; P=0.07) and live weight (2131 vs. 2100 g; P=0.07) values of rabbits at the end of the first period after weaning (55 d of age) were slightly higher in rabbits fed \u3b2-glucans diets compared with those fed mannanoligosaccharides diets. The slaughter traits were similar among the experimental groups. In conclusion, under the rearing conditions of the present trial and in absence of epizootic rabbit enteropathy, the dietary supplementation with mannanoligosaccharides and/or \u3b2-glucans did not produce any appreciable advantage in growth performances and carcass quality of meat rabbits

Dietary supplementation with mannanoligosaccharides and \u3b2 glucans in growing rabbits. 2 Gut Barrier and intestinal microbiota after weaning

The aim of this work was to determine the effect of yeast mannanoligosaccharides (MOS; Actigen, Alltech) and yeast \u3b2-glucans on gut barrier and intestinal microbiota in rabbits. A control diet (C) was formulated to meet rabbit growth requirements. G1 and G2 diets were obtained by supplementing C diet with \u3b2-glucans from Saccharomyces cerevisiae (100 and 200 mg/kg respectively), M1 and M2 diets were supplemented with mannanoligosaccharides (Actigen, Alltech) (400 and 800 mg /kg respectively), and GM diet was supplemented with 100 mg/kg of \u3b2-glucans + 400 mg/kg of MOS. Ninety six rabbits weaned at 32 days of age were randomly assigned to the six experimental diets and slaughtered 15 days after weaning. The type of diet did not affect villus length and goblet cell counts, but crypt depth was reduced at the highest levels of MOS and \u3b2-glucans supplementation. Both MOS and \u3b2-glucans increased specific sucrose activity (P = 0.001) and soluble protein concentration (P < 0.05) in jejunal mucosa; they also modified ileal and caecal microbiota and modulated the immune response. Compared with the control diet, the supplementation with 200 mg/kg of \u3b2-glucans (G2) and 800 mg/kg of MOS (M2) reduced the expression of iNOS in ileum. Rabbits fed the M2 diet showed also the lowest mRNA abundance of IL6. In appendix, rabbits fed G2 showed increased IL6 expression and those fed the M2 reduced the expression of INF\u3b3. In conclusion, MOS and \u3b2-glucans changed intestinal microbiota and modulated the immune response by reducing the expression of some pro-inflammatory cytokines in ileum and caecum of weaned rabbits

Efecto de la adici\uf3n en el pienso de mananoligosac\ue1ridos y \u3b2-glucanos de levaduras sobre la microbiota intestinal de gazapos

This work aimed to study the response of the ileal and caecal microbiota after dietary supplementation with MOS (Actigen, Alltech) and \u3b2-glucans. Sixty four weaning rabbits were randomly assigned to 4 experimental diets and fed ad libitum for 13 days as following: a control diet (C), G2 and M2 diets obtained supplementing C diet with 200 mg/kg of \u3b2-glucans or 800 mg/kg of MOS, respectively and MG diet was supplemented with 100 mg/kg of \u3b2-glucans + 400 mg/kg of MOS. The microbiota of ileum and caecum digesta was analyzed using TRFLP technique. Animals fed G2 and M2 decrease the biodiversity in ileum (P<0.010), but did not affect the biodiversity of the caecal microbiota. MG diet led to a microbiota distant from others diets both in ileum and caecum, especially from control group (R=0.95, R=0.69 respectively; P<0.001). Similarity analysis and diversity calculation provided that microbiota changes caused by the additives have been most important in ileum than in caecum. In conclusion, the MOS and the \u3b2-glucans cause changes in ileal and caecal microbiota of young rabbits after weaning. The mixture of both seems to have a distant effect than the individual components

European ring-test on the chemical analyses of total dietary fibre and soluble fibre of compound diets and raw materials for rabbits

Due to the role of soluble fibre (SF) on the digestive physiology and gut health of post-weaning rabbits and to the lack of reference methods for SF determination, in the framework of the harmonization activity on rabbit science methodologies carried out by EGRAN (European Group on Rabbit Nutrition), a collaborative study was achieved on the determination of total dietary fibre (TDF), aNDF corrected for protein and ash (aNDFcorr) and SF calculated as the difference between TDF and aNDFcorr. Five EGRAN laboratories analysed nine samples: four compound diets and five raw materials (alfalfa meal, wheat bran, grape marc, sunflower meal, sugarbeet pulp) with different levels of fibre fractions and SF. Each sample was analysed 3 runs for TDF and aNDFcorr. TDF was analysed according to the AOAC Method 991.43 using the kit and the procedure of Megazyme\uae. TDF averaged 48.2% DM, with one laboratory having higher values (49.3% vs 47.9%; P<0.001). The TDF values varied among samples (P<0.001), from about 40% DM for diets to 60% DM for grape marc and sugarbeet pulp. Repeatability (SR=0.95% DM) and reproducibility of TDF (SL=1.68% DM) were good with a low coefficient of variation among laboratory: CVL= 3.9%. The aNDFcorr (mean 37.1% DM) significantly differed from laboratories that used Ankom system (36.4% DM) to laboratories that used Fibertech equipment (38.3% DM). The differences among laboratories due to the equipment and to the corrections for ash and protein explained the poorer repeatability and reproducibility of aNDFcorr determination, with CVL=6.6%. SF values differed (P<0.001) among laboratories (from 9.6% to 12.0% DM) and samples (from 4.0% DM of wheat bran to 8-11% DM of diets and alfalfa meal to 24.3% DM of sugarbeet pulp). The among-laboratory variability of SF was higher (SL=2.97% DM; CVL=26.8%), due to the variability of both TDF and aNDFcorr analyses. In conclusion, TDF analysis was characterized by good repeatability and reproducibility, but it was less reproducible in case of raw materials with high SF levels. The among laboratory variation increased with aNDFcorr, because of the differences in analytical equipment and the procedure for protein and ash corrections. Finally SF reproducibility appeared rather good for complete diets and raw materials with low or medium concentration (SF 4-10% DM), but it was affected by the analytical errors of both TDF and aNDFcorr and needs a better harmonization