Effects of Increasing Levels of Defatted Rice Bran on Intestinal Physical Barrier and Bacteria in Finishing Pigs

SIMPLE SUMMARY: In China, the largest pig-raising country in the world, feed resources are gradually scarce, and the imports of grain crops including corn are increasing. Therefore, it is an urgent problem to find alternatives to grain feed materials. Defatted rice bran (DFRB), an abundant and underutilized agricultural coproduct of brown rice refining process, is rich in energy and dietary fiber (DF). The aims of this study were to assess the effects of increasing levels of DFRB (0%, 7%, 14%, 21%, and 28% DFRB) as a replacement for corns on intestinal physical barrier function and numbers of specific bacteria, and determine the optimal substitution level of DFRB in finishing pigs. We found that 7% DFRB as a replacement for corns had a beneficial effect on intestinal wall thickness, Bifidobacterium and Clostridium perfringens (C. perfringens), and had no adverse effect on intestinal permeability and Escherichia coli. ABSTRACT: The aims of this study were to assess the effects of increasing levels of DFRB as a replacement for corns on intestinal physical barrier function and bacteria of finishing pigs. A total of 35 castrated finishing pigs (age: 158.5 ± 2.0 d, initial body weight: 62.9 ± 0.8 kg) were randomly divided into five dietary treatments (seven replicates/treatment) for a 28-day experimental period, i.e., a control diet with basal diet, and four experimental diets in which maize was replaced by 7%, 14%, 21%, and 28% DFRB, respectively. The results showed that serum endotoxins concentration and diamine oxidase (DAO) activity were both increased (linear, p = 0.0004, 0.001, respectively) with DFRB level. However, compared with control group, serum endotoxins concentration and DAO activity were not different in pigs fed with 7% DFRB in the diet. There was a quadratic response in serum D-lactate concentration to the increased DFRB (quadratic, p = 0.021). In the cecum, thickness of the intestinal wall significantly increased with increasing levels of DFRB in the diets (linear, p = 0.033), while crypt depth/thickness of the intestinal wall ratio significantly decreased with increasing level of DFRB in the diets (linear, p = 0.043). In the jejunum, total bacteria, Escherichia coli, and Bifidobacterium all responded quadratically to increasing levels of DFRB in the diets (quadratic, p = 0.003, 0.001, 0.006, respectively). Additionally, there was no difference in Escherichia coli in pigs fed 0%, 7%, and 14% DFRB diets. In the colon, there were quadratic responses in C. perfringens to the increased DFRB (quadratic, p = 0.023). C. perfringens reduced as the DFRB concentration increased from 0% to 14% and then increased. When D-lactate, total bacteria, Escherichia coli, Bifidobacterium, and C. perfringens were considered, the optimal substitution level of DFRB were 12.00%, 11.84%, 7.50%, 8.92%, and 15.92%, respectively. In conclusion, 7% DFRB had a beneficial effect on intestinal wall thickness, Bifidobacterium and C. perfringens, and had no adverse effect on intestinal permeability and Escherichia coli.