The effect of rice husk as an insoluble dietary fiber source on intestinal morphology and Lactobacilli and Escherichia coli populations in broilers

Background: There are some reports on the positive effects of dietary insoluble fiber on the performance of broilers. Objectives: This study was carried out to determine the effect of inclusion rate and particle size of rice husk in the diet of broilers on the ileal and cecal bacteria populations and small intestine morphology. Methods: The experimental diets consisted of a control husk-free diet and four diets containing 7.5 or 15 g/kg rice husk with particle sizes of less than 1 mm or between 1-2 mm. Results: The dietary insoluble fiber did not affect feed intake of the experimental groups. The best body weight gain and feed conversion ratio was recorded in the broiler chickens fed the diet containing 15g/kg rice hulls with particle size of less than 1 mm (p<0.05). In the duodenum and jejunum, the crypt depth to villi height ratio in the control group was significantly lower than other groups (p<0.05). In the ileum, all the birds fed rice husk except the group fed the diet that contained 15g/kg rice husk with particle size of 1-2 mm, had higher Lactobacilli and lower E. coli and coliforms populations than the control group (p<0.05). Conclusions: The results of the present study suggest that the 7.5g/kg dietary inclusion and more coarse particles size of rice husk (1-2 mm) were more effective to promote broiler growth performance. The positive effects of dietary insoluble fiber on the growth performance of broilers in this study are probably a result of favorable changes in the bacteria populations of the gastrointestinal tract and not any improvement in small intestine absorptive capacit