The increase of dietary soluble fibre reduced caecal pH (5.88–5.70; P=0.02) and tended to increase total VFA production (73.8–82.8 mmol/L; P=0.10), while it reduced the valerate proportion (0.43–0.35 mmol/100 mmol VFA; P=0.01). On the contrary, the dietary soluble fibre level did not modify gut mucosa morphology.