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Two diets for finishing pigs were used to determine the effect of adding water into the mixer on processing characteristics and pellet quality. Diet 1 was based on barley, oats and soybean meal (barley-based diet) and Diet 2 was based on maize and soybean meal (maize-based diet). Both diets were produced without and with use of an expander.
Adding up to 120g water/kg into the mixer prior to steam conditioning and pelleting (steam conditioning) of the barley-based diet, improved pelleting efficiency, pellet durability index (PDI) and modified PDI (with five hexagonal nuts added into the tumbling box), by 15, 10 and 10%, respectively. When water was added into the mixer prior to expanding the barley-based diet, PDI increased from 93 to 95% and modified PDI from 91 to 94%. The maize-based diet was processed with motor load held constant to maximize feed mill output, and production rate held constant to minimize energy use. At a constant motor load and a constant production rate, adding up to 30g water/kg into the maize-based diet prior to steam conditioning increased pelleting efficiency by 22 and 9%, PDI was improved from 84 to 89% and from 79 to 87%, respectively. Expander conditioning of the maize-based diet increased PDI from 92% at none to 94% at 30g/k g water addition. Correspondingly, modified PDI was increased from 89 to 93% at none and 30g water/kg into the mixer prior to expander conditioning.
It is concluded that adding water into the mixer before steam conditioning improved pelleting efficiency and pellet quality in barley- and maize-based diet for finishing pigs.
KK Lundblada,JD Hancock, KC Behnkec, E Prestløkkena, LJ McKinneyc, M Sørensend. 2009. Animal Feed Science and Technology, 150: 295-302.
