Animals and experimental design

Sixty 5-week-old New Zealand specific pathogen-free rabbits of both genders (purchased from a rabbit farm in Tianquan, Ya’an, Sichuan) were used (mean weight of 890 ± 32.2 g). They were randomly assigned to two groups according to their weight (ERE group and normal group). All rabbits were placed in individual cages under controlled environmental conditions and were provided access to food and water ad libitum at Sichuan Agricultural University, China. To increase the incidence of ERE, the ERE group was fed a diet with a low fibre content according to a previous report⁹, and both diets lacked coccidiostats and antibiotic (CF = 9.49% vs.13.59%, ADF = 13.27% vs. 17.98%, NDF = 21% vs. 30%). The two diets were formulated according to the nutrient recommendations of de Blas and Wiseman⁴⁸, and had similar energy and protein values, and the constituents and nutritional values are shown in Table 2. After seven days of adaptation and at the age of 55 days, six rabbits suffering typical ERE symptoms, such as anorexia, lethargy, abdominal distension, a hunched posture, caecal impaction and a watery sound in the gut, were selected at randomly from different cages of the low-fibre group. Additionally, six normal rabbits were selected randomly from the high-fiber group. All selected rabbits from each group were slaughtered and their stomach, intestinal and caecal contents were collected on the same day at 0800. The samples were frozen immediately at −80 °C until use.

Ingredient and nutrient composition of the experimental diets.

^aPremix composition (by kg diet): vitamin A, 10000 IU; VD3, 1000 IU; VE, 40 mg; VK, 1 mg; VB6, 30 mg; nicotinic acid, 150 mg; Cu, 20 mg; Fe, 50 mg; Mn, 30 mg; Mg, 150 mg; Zn, 50 mg; I, 0.5 mg; Se, 0.05 mg; Co, 0.2 mg.

^bDM, NDF, ADF, CF and NFE were determined values, and DE, CP, Ca, P, Lys and Met + Cys were calculated values.