Incorporation of unfermented or fermented de-oiled rice bran meal into a rabbit's diet impacts growth performance, nutrient digestibility, cecal microbiota.

Objective: This study assessed the effects of incorporating unfermented or fermented rice bran meal (RBM) into a rabbit's diet on their growth performance, cecal microbiota, and intestinal health.

Methods: A total of 21 male weaned New Zealand White rabbits aged 6 weeks were randomly allocated into 3 groups (n = 7). Rabbits consumed the basal diet in the CON group and the basal diet with a 20% substitution of either unfermented RBM (UFRBM group) or fermented RBM (FRBM group) for 8 weeks. The RBM was fermented by a combination of Lactobacillus johnsonii L63 with hydrolytic enzymes (cellulase (100 U/g), phytase (1.25 U/g), and papain (300 U/g)) and incubated for 60 hours at 37 °C and a pH value of 4.8.

Results: Our results demonstrated that the rabbits' growth performance (FBW, ADG, and FCR), serum biochemical variables, and cecal microbiota for α-diversity and β-diversity at the phylum level didn't differ among the treatments (P ˃ 0.05). The FRBM increased nutrient digestibility, antioxidant capacity, intestinal histomorphology, digestive enzymes, nutrient transporter expression, short-chain fatty acid (SCFA) concentration, and the abundance of glycolysis/gluconeogenesis and carbohydrate digestion and absorption metabolic pathways than those in the CON group (P ˂ 0.05), while it was improved in most parameters than the UFRBM. The UFRBM enhanced the ADFI, ether extract digestibility, jejunal villi height, solute carriers of family 3 member 1 (SLC3A1), family 1 member 1 (SLC1A1), occludin (OCLN) up-regulations, SCFA, the relative abundance of V9D2013 group and Rikenella at the genus level, and the glycolysis/gluconeogenesis metabolic pathways, and lowered the malonaldehyde (MDA) concentration than those in the CON group (P ˂ 0.05).

Conclusion: The two formulas incorporating 20% of UFRBM or FRBM in rabbit diet should be recommended to farmers, particularly the FRBM, to decrease the reliance on corn and soybean meal for rabbit production.