Effects of bean husk feeding on gastro-intestinal fermentation andmicrobiota of rats
共生基盤科学専攻 食品安全・機能性開発学講座

1.

副生物科学 Htun Myint

Introduction
Bean husks, rich in fiber, can be considered as feed material for various animals. Lablab bean (Dolichos lablab)and chickpea (Cicer arietinum) husks were found to increase digestibility of rice straw diet by stimulating specific rumen
bacteria in sheep (Tin et al., 2012; Fuma et al., 2012). Lablab bean husk containing oligosaccharides was also found tostimulate beneficial intestinal bacteria (lactobacilli and bifidobacteria) in pure culture study (unpublished). Other beanhusks might have a similar potential. In the present study, feeding experiments were conducted to evaluate functions of
three different bean husks in intestinal fermentation and microbiota of rats. Such research may contribute to futureapplication of bean husks to mono-gastric animals including dogs, cats and even humans.
2. Materials and Methods
Two experiments were carried out using 5-week-old 20 rats (Exp. 1) and 15 rats (Exp. 2), respectively. In Exp.1,
rats were equally divided into 4 groups and fed either of the following diets for 3 weeks: purified diet (AIN93G) containing
5% cellulose (Cellulose), same diet in which cellulose was replaced by corn starch (Starch), lablab bean husk (Lab) or
soybean husk (Soy). In Exp.2, rats were equally divided into 3 groups and fed either Cellulose, Starch or the purified dietin which cellulose was similarly replaced by chickpea husk (Chick). Feed intake and body weight were measured dailyand weekly, respectively. Rats were sacrificed at 8 w ee k of age to take blood and digesta samples and then weights oforgan and digesta were recorded. Glucose and cholesterol were analysed in the blood plasma. The pH, fermentation
products (short chain fatty acid, lactate, succinate, ammonia, indole and skatole) and microbes were monitored in ileal
and cecal digesta. Microbiota was characterized by PCR/ DGGE and real-time PCR.
3.

Results and Discussion
In Exp.1, feed intake, body and organ weights, blood components, cecal ammonia and succinate were notdifferent among diets. Cellulose, Soy and Lab, especially Lab, lowered cecal indole and skatole levels. Rats on Lab andSoy showed higher concentrations of cecal short chain fatty acid and lactate than those on Cellulose, accompanying withlower pH. Ileal bacteria were occupied by lactobacilli and not greatly affecte d by diet. However, changes with diet in
cecal microbiota were apparent by different DGGE banding patterns and higher abundance of lactobacilli in rats fed husk s
especially Soy. The abundance of Akkermansia muciniphilus was higher in Lab. In Exp.2, no apparent change with Chick
was observed in parameters except the followings. Chick lowered total cholesterol level in the blood, cecal pH, indoleand skatole, while increased cecal butyrate level with alteration of cecal microbiota determined by DGGE. All 3 beanhusks are equally effective for lowering harmful fermentation products (indole and skatole). Lab and Soy are
more favorable in stimulating beneficial cecal bacteria (Akkermansia and lactobacilli, respectively). Only
Chick is indicative of blood cholesterol–lowering action. Based on these, bean husks tested in the present
study are considered to be a functional feed for promoting the health of monogastric animals.