Four experiments were carried out to study the possible differences in metabolizable energy (ME) of meals (RSM) or expeller meals (RSE) from double-low rapeseed (Expt. 1), the influence of processing on ME (Expt. 2) and on relative phosphorus (P) bioavailability (Expt. 3) in RSM, and effect of RSM inclusion on growth performance of broilers (Expt. 4). For Expt. 1, diets with 300 g/kg RSM from 11 RSM and 4 RSE varieties were fed to broilers from d 14 to 21, with excreta collection on d 19 to 21. Each treatment had 8 replicates and 3 birds per replicate. Energy metabolizability of RSM of a specialized high glucosinolate variety (V275OL) was greater (P < 0.05) than all the other varieties. In Expt. 2, two RSM varieties were processed with mild or conventional processing condition. There were no variety effects on ME, but ME and MEn were greater (P < 0.01) for RSM processed by mild processing condition. In Expt. 3, P bioavailability of RSM was determined, relative to MSP, using growth performance and tibia ash as responses. Phosphorus relative bioavailability values were greater (P < 0.05) in RSM of DK Cabernet variety processed using the mild processing condition. In Expt. 4, two RSM varieties were added to wheat-soybean meal-based diet at the rates of 50, 100, 150, or 200 g/kg and fed to broilers from d 0 to 42. Inclusion of 150 and 200 g/kg of RSM resulted in reduced weight gain and increased feed conversion ratio (FCR) compared (P < 0.01) with the lower inclusion levels during the starter phase. For the entire trial (d 0 to 42), weight gain was greater (P < 0.01) for birds receiving diets with RSM from PR46W21 variety. It was concluded from the experiments that apart from the residual ether extract content, variety differences had no impact on ME of RSM, conventional processing reduced ME and relative bio-availability of P; and that the maximum level of RSM inclusion depends on maximum growth performance level desired.
Keywords: broilers; growth; metabolizable energy; phosphorus bioavailability; rapeseed meal.
© 2017 Poultry Science Association Inc.