Activity of supplemental enzymes and their effect on nutrient utilization and growth performance of growing chickens as affected by pelleting temperature

Activity of supplemental enzymes in a barley-soybean-maize based diet at 60 , 75 and 90 degrees C pelleting temperatures was studied using feed viscosi ty, in-vitro enzyme activity and broiler performance data. High pelleting temperatures increased feed viscosity but supplemented enzym es reduced the viscosity at all three temperatures levels by 11, 14 and 17% , respectively. Water intake and losses in excreta of birds were found to b e affected by feed viscosity. Activity of cellulase enzyme, measured using the radial diffusion method, was unaffected at 60 and 75 degrees C, but red uced by 73% in feed processed at 90 degrees C. Enzymes increased the weight gain of broilers by 11.1% at 90 degrees C, but no effect could be seen at low pelleting temperatures possibly due to high dietary protein and energy contents. Feed intake was unaffected by enzymes. Birds consumed 6% more fee d and grew 9% faster when the pelleting temperature was increased from 60 t o 75 degrees C. Reduced feed intake and daily weight gain observed at 90 de grees C could be fully compensated by the enzyme supplementation. High pell eting temperature reduced energy metabolizability (3.2%) and nitrogen utili zation (4%) but enzyme almost compensated them (by 3.3% and 2.6%, respectiv ely). No interaction could be detected between the pelleting temperatures a nd enzymes. It is concluded that pelleting temperatures as high as 90 degrees C drastic ally reduce cellulase activity, energy and nitrogen utilization thus loweri ng broiler performance. Either the remaining activity of cellulase or other thermostable enzymes can prevent the losses.