Intestinal structure and function of broiler chickens on diets supplemented with a mannan oligosaccharide

A study was conducted to evaluate the response of broiler chickens to a commercial synthetic mannan oligosaccharide, Bio-Mos™ (BM), included in sorghum/lupin-based diets at 0.0, 1.0, 3.0 or 5.0g kg-1 diet. The diets were fed between 7 and 28 days of age, and both the gross response and mechanisms involved were evaluated. The highest level of BM in the diet resulted in longer (P < 0.01) jejunal villi than those observed at other levels of supplementation. The RNA content of the ileal mucosal homogenate was significantly greater (P < 0.05) in chicks raised on diets supplemented with 3.0 and 5.0g BMkg-1 diet than in other groups. The protein/DNA ratio of the jejunal mucosal homogenate was also higher (P < 0.05) in chicks fed the 1.0g BMkg-1 diet than in chicks fed the other diets. The protein/RNA and RNA/DNA ratios in ileal homogenates were significantly (P < 0.01) influenced by the presence of BM in the diet. There were significantly greater specific activities of maltase (P < 0.01), leucine aminopeptidase (P < 0.05) and alkaline phosphatase (P < 0.001) in the jejunum as a result of supplementation with BM. Digestive enzyme activities in the ileum were unaffected. L-Tryptophan uptake by jejunal brush-border membrane vesicles was significantly higher (P < 0.01) in chicks raised on the 5.0g BMkg-1 diet than in the other chicks. The supplement led to minor improvement in body weight but no improvement in feed conversion ratio. These effects were related to changes in digestive enzyme activities and, perhaps, amino acid transport. © 2001 Society of Chemical Industry.