Defatted rice bran nonstarch polysaccharides in broiler diets: Effects of supplements on nutrient digestibilities

The efficacy of bile salt, lipase, or fiber-degrading enzyme supplementation in the nonstarch polysaccharides (NSP) of defatted rice bran (DRB) diet on nutrient digestibilities and energy value was examined in 1- to 14-d-old chicks. Two types of NSP, Extracted-NSP (isolated from DRB, 15%/kg of diet) and Natural-NSP (given as intact DRB, 30% /kg of diet), were tested in this experiment. The 15%-Extracted- and the 30%-Natural-NSP provided a comparable amount of total-NSP concentration. The birds fed the Extracted-NSP diet had better weight gain and lower feed: gain ratio compared with those given the Natural-NSP diet, although fat digestibility did not differ between the two NSP diets. Addition of bile salt improved fat digestibility more than that of lipase or fiber-degrading enzyme in both NSP diets on d 7 (P<0.001). There was a significant NSP type x supplements on fat digestibility showing that the effect of the fiber-degrading enzyme during the first week of age was more profound (P<0.01) in diets containing the Extracted-NSP than those with the Natural-NSP. But, pancreatic lipase activity did not correlate well with fat digestibility. During the second week of age, the effect of bile salt on protein digestibility was inferior whereas the effect of lipase was superior in the two NSP diets (P<0.05). The dietary MEn values of the diets containing the Extracted-NSP were greater than those with the Natural-NSP (P<0.001). Bile salt had the greatest effect among the three supplements on the ME sub(n) (P<0.001) of the NSP diets. Tibia ash content of the birds was adversely affected only by feeding diets containing the Natural-NSP. The current study suggested that bile salt appeared the most effective supplement in increasing fat digestibility and energy value of the diet containing considerable amounts of defatted rice bran-nonstarch polysaccharides.