The effect of neutral detergent soluble fibre (NDSF) level on digestibility, fermentation traits, intestinal microbiota and performance was studied in weaned rabbits. A control diet (DA) containing 103 g NDSF/kg DM included dehydrated alfalfa as the main source of fibre. Another diet (B-AP) was formulated by replacing half of the dehydrated alfalfa with a mixture of beet and apple pulp resulting in 131 g NDSF/kg DM. A third diet (OH) was obtained by substituting half of the dehydrated alfalfa with a mix of oat hulls and a soybean protein concentrate and contained 79 g NDSF/kg DM. All diets contained similar levels of total fibre (NDSF + neutral detergent fibre), starch and protein (446, 208, and 199 g/kg DM, respectively). Forty-two rabbits (14/diet) weaned at 25 days were used to determine faecal digestibility from 32 to 35 days of age. This group, plus another nine rabbits/diet (23/diet), were used to determine weight of stomach and caecum and their contents, caecal fermentation traits and similarity rate (SR) of intestinal microbiota. Another 105 and 245 weaned rabbits were used to determine growth traits and mortality, respectively. From 25 to 39 days of age, rabbits were fed the experimental diets and from 39 to 60 days they were fed a commercial diet, including robenidine hydrochloride in all diets. Drinking water was supplemented with apramicine sulfate and tylosine tartrate throughout the experimental period. Faecal and energy digestibility increased linearly by 8% and NDF digestibility by 43% between extreme diets with NDSF inclusion (P < 0.001). Weight of total gastrointestinal tract decreased linearly and quadratically with NDSF reduction (P = 0.008 and P = 0.089, respectively). Stomach pH decreased linearly with increasing levels of NDSF (P ≤ 0.041). Weight of caecal contents increased linearly between animals fed OH and B-AP diets (P < 0.001). Level of inclusion of NDSF had no effect (P ≥ 0.12) on pH, VFA concentration and VFA molar proportions in caecal contents. Treatments appeared to influence the SR of caecal microbiota but a lesser effect was observed on ileal microbiota. Post weaning feed efficiency (25-39 days) increased linearly (P < 0.001) with NDSF inclusion by 10% between extreme diets, and by 3% in the whole fattening period (P = 0.027). Average feed intake during the post weaning (25-39 days) and the whole fattening period increased with NDSF reduction (P ≤ 0.079). No effect of NDSF was detected on average daily gain (P ≥ 0.15). Mortality decreased linearly with increasing levels of NDSF in the post weaning and in the whole fattening period (P = 0.086 and 0.016, respectively). © 2009 Elsevier B.V. All rights reserved.
- Growing rabbits
- Intestinal microbiota
- Neutral detergent soluble fibre