The effect of steam-conditioning rate on the pelleting process

A poultry layer-diet was used in experiments to determine the effects of steam-conditioning level on pelleting variables. Dry pelleting was compared with steam conditioning (to 65 and 80° C) before pelleting, at both constant and maximum production rates. Samples were obtained before and after conditioning, and after pelleting. Electrical energy used by the pellet mill was measured with a watt-hour meter, and the amount of steam used for conditioning was calculated using steam tables. Temperature rise of the meal being extruded through the die and electrical energy required to pellet showed that steam decreased mechanical friction during pelleting. Pellet durability and percentage of fines from the scalper showed that steam improved pellet quality. Pressing the mash through the pellet die caused more starch damage during dry pelleting than during steam pelleting. Starch was not damaged during the steam-conditioning process. Total energy required for pelleting (electrical plus steam) was highest for the 80° C treatment. However, steam conditioning allows increased production rates and improved pellet durability during handling and transportation of finished feeds.