The effect of expander processing and pelleting on the nutritive value of feed for growing and finishing pigs

Two experiments were conducted to determine the effect of pelleting and/or expander processing on the nutritive value of feed when fed to growing and finishing pigs. Experiment 1 determined the effects of pelleting and/or expander processing on the apparent nutrient digestibility of the diets. In experiment 2, productive performance and carcass characteristics were determined in group-fed pigs (n = 312) offered identical diets in raw pellet form (T1), expander-processed pellet form (T2), raw meal form (T3) and expander-processed meal form (T4). The expanded diets were expander processed at 105 degrees C for 5 s at 35 bar pressure. The pellet diets were steam pelleted at 85 degrees C into 3.0 mm pellets. Pelleting of the diets increased organic matter (P < 0.05), protein (P < 0.01), energy (P < 0.01) and ash (P < 0.01) digestibility as well as the digestible energy (DE) content of the diets (P < 0.01). Expander processing had no effect on the organic matter, protein and energy digestibility of the diets. There was a significant interaction (P < 0.05) between pelleting of the diet and expander processing in DE content of the diets. Expansion had no effect on the DE content of the pelleted diets; however, expansion increased the DE content of the meal diets (P < 0.05). In experiment 2 there was a significant interaction between the physical form of the diet and expansion in feed intake during the grower and finisher period (P < 0.01). Expander processing had no effect on feed intake in the pelleted diets; however, expansion decreased feed intake of the meal diets (P < 0.001). Both pelleting and expansion of the diets decreased growth rate during the grower and finisher period (P < 0.05). Pelleting of the diets improved feed conversion ratio (FCR) during the grower and finisher period (P < 0.05), while expander processing had no effect on FCR.