News last update:6 Aug 2012

Extra water in mixer gives better pellets

Scientists from Norway (Felleskjøpet Fôrutvikling and Norwegian University of Life Sciences) and the US (Kansas State University) have added extra water to the mixer prior to steam conditioning to study the effects on pellet quality of pig feeds.

Two diets for finishing pigs were used to determine the effect of adding water into the mixer on processing characteristics and pellet quality.

The researchers used a barley-based diet and a maize-based diet. Both diets were produced without and with use of an expander.

Adding up to 120 g water/kg into the mixer prior to steam conditioning and pelleting 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 30 g 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 30 g/kg water addition.

Correspondingly, modified PDI was increased from 89 to 93% at adding none and 30 g water/kg into the mixer prior to expander conditioning.

The overall conclusion from the experiment was that adding water into the mixer before steam conditioning improved pelleting efficiency and pellet quality in barley- and maize-based diet for finishing pigs.

The full report can be purchased from ScienceDirect.

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