The nutritional value of wheat distillers dried grains and solubles (WDDGS) in aquaculture is poor because of its relatively low crude protein (CP) and high fibre content, according to Felipe E. Reveco of the University of Saskatchewan, Canada, and Murray D. Drew at the Norwegian University of Life Sciences in Oslo.
In their paper in Canadian Journal of Animal Science, they explain that, in their study, WDDGS was fractionated using grinding, sieving and elutriation sequentially. The WDDGS was ground in a hammer mill using a 3mm screen and sieved using six sieves (20M, 30T, 40T, 50T, 60M and 80M) into seven fractions (>841, 590840, 426589, 298425, 251297, 178250 and <177m). Elutriation was then performed to further fractionate based on particle shape and density.
The higher density sub-fractions from the three smallest particle size fractions were mixed to produce a fractionated WDDGS containing (per kg) 20.7 MJ gross energy, 454.6g crude protein, 260.4g neutral detergent fibre (NDF) and 93.2g acid detergent fibre (ADF).
The digestibility of the unprocessed and fractionated WWDGS products was assessed in rainbow trout.
Apparent digestibility coefficient of the dry matter, gross energy, acid ether extract (AEE), ash and amino acids (AA) did not differ between the unprocessed material and the fractionated WDDGS (P>0.05).
However, the apparent digestibility coefficient of crude protein was higher for fractionated WDDGS (0.88) than the unprocessed WDDGS (0.85) (P<0.05).
Reveco and Drew concluded that this fractionation scheme can be used to improve the nutritional value of WDDGS for rainbow trout.
Reference
Reveco F.E. and M.D. Drew. 2012. Fractionation of wheat distillers dried grains and solubles by particle size and density improves its digestible nutrient content for rainbow trout. Canadian Journal of Animal Science, 92(2):197-205. doi:10.4141/cjas2011-113
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August 2012
