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 jprocessing 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 (T3). The expanded diets were expander processed at 105 degreesC for 5s at 35bar pressure. The pellet diets were steam pelleted at 85 degreesC into 3.0mm 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 amid expansion in feed intake during the grower and finisher period (P < 0.01). Expander processing hard 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 a:nd 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. (C) 2000 Society of Chemical Industry.