Parameters monitored during the pelleting process and their relationship to xylanase activity loss
2020
Pope, J.T. | Brake, J. | Fahrenholz, A.C.
Exogenous enzymes have been regularly used in broiler diets to improve the value of raw ingredients by enhancing their digestibility. Broiler feed has also been most commonly pelleted, which has exposed mixer-added exogenous enzymes to pressure and heat. These conditions have often resulted in mixer-added exogenous enzyme denaturation and inactivation. The present experiment was intended to define the relationship between parameters monitored during the pelleting process, such as change in temperature between hot pellets and conditioned mash (ΔT), pellet durability index (PDI), and pellet mill energy consumption (PMEC) and the stability of a mixer-added xylanase throughout the pelleting process. To generate a range in values for ΔT, PDI, and PMEC, diets were pelleted with varying concentrations of fat and degrees of saturation of fat through two pellet mill dies with varying length-to-diameter ratios at a constant temperature of 82 °C. It was determined that as ΔT, PDI, and PMEC increased, xylanase recovery in pellets relative to unconditioned and conditioned mash decreased (P = 0.001). When select parameters monitored during the pelleting process were combined with select controlled factors, a multiple regression model was generated (P = 0.001; R2 = 0.84). These data indicated that practices implemented to improve PDI may negatively affect the stability of heat sensitive mixer-added exogenous enzymes during the pelleting process and that predictive models could be generated to better predict the impact of implementing feed manufacturing practices to improve pellet durability on enzyme thermostability.
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