Effects of processing technologies and pectolytic enzymes on degradability of nonstarch polysaccharides from rapeseed meal in broilers

Rapeseed meal (RSM) contains a high level of nonstarch polysaccharides (NSP) that are not well degraded in poultry and interfere with digestion of other nutrients as protein, starch, and fat. By altering physicochemical properties of NSP from RSM, processing and enzyme technologies might improve digestive utilization of RSM, enhancing its potential as a source of nutrients in poultry diets. The effects of wet milling and extrusion in combination with pectolytic enzymes on the degradability of RSM in broilers were investigated in a 3 × 2 factorial arrangement. Wet milling and extrusion did not affect total tract apparent digestibility of DM, CP, crude fat, and nonglucose polysaccharides (NGP). Addition of pectolytic enzymes did not affect total tract apparent digestibility of CP and crude fat, but improved degradability of NGP by 9 to 20% units (P <0.001), independent of prior technological processing of RSM. This coincided with an increased NGP concentration in the ceca (4 to 7 g/g of cobalt, P <0.001), indicating that more NGP were solubilized such that they could enter the ceca and become available for fermentation. Particle size reduction facilitated solubilization of polysaccharides from RSM, increasing the concentration of NGP found in the ceca (4 g/g of cobalt, P = 0.008). Without help of additional pectolytic enzymes, those solubilized structures could, however, still not be degraded by the cecal microbiota. Feed intake, BW gain, and feed conversion ratio were not affected. No interaction between processing technologies and enzyme addition was found. Apparently, the processing technologies studied were not facilitating accessibility of NSP to pectolytic enzymes added to the feed in vivo.