Optimizing feed efficiency and nitrogen excretion in growing rabbits by increasing dietary energy with high-starch, high-soluble fibre, low-insoluble fibre supply at low protein levels

A total of 282 crossbred rabbits of both genders were divided into six experimental groups and fed ad libitum six diets formulated in a 2×3 factorial arrangement based on three dietary energy levels (low, approximately 8.45 MJ/kg; medium, 9.9 MJ/kg: and high, 11.5 MJ/kg) and two crude protein levels (15% and 17%). The increase of dietary energy was obtained by a simultaneous increase of dietary starch (9.1%, 13.7%, and 17.9%) and soluble fibre (4.8%, 7.1%, and 9.4%) at the expense of acid detergent fibre (23.0%, 18.0%, and 13.5%). Growth performance and nitrogen excretion from weaning until slaughter, and digestive traits were monitored. The increase of dietary energy enhanced the apparent digestibility of dry matter (50.8%, 60.5%, and 71.5%; P