Energy Determination of Maize By-Products Using Composition Analysis

Chemical analysis has helped researchers to develop a better prediction of the energy value of distillers dried grains with solubles (DDGS) and other ethanol by-products.
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S.J. Rochell of Auburn University and co-workers there and at USDA's ARS Agroecosystems Research Unit in Ames, Iowa, presented their work on the energy determination of corn co-products fed to broiler chicks from 15 to 24 days of age and use of composition analysis to predict AMEn at this year's Poultry Science Association Annual Meeting in Denver, Colorado.

They explain that 15 co-products collected from various wet and dry milling plants were fed to broiler chicks to determine nitrogen-corrected apparent metabolisable energy (AMEn) and to generate an equation to predict AMEn based upon each ingredient's chemical composition. Co-products included: DDGS (6), HP-DDG (2), dehydrated corn germ (2), corn germ meal, corn bran, corn gluten meal, corn gluten feed and dehulled degermed corn. A control diet was fed containing corn, soybean meal, dextrose (15 per cent), dicalcium phosphate, limestone, salt, vitamins and trace minerals.

Test diets were formulated by mixing the control diet with 15 per cent of a co-product at the expense of dextrose. The diets were fed to 1,920 Ross × Ross 708 chicks (10 per pen; five males and five females), which were randomly assigned to 15 dietary treatments (12 replicate pens). Broilers were fed experimental diets from 15 to 22 days of age followed by a 48-hour total excreta collection period.

Ingredients were analysed for gross energy (GE), crude protein (CP), moisture, crude fat, crude fibre, ash, total dietary fibre, neutral detergent fibre and acid detergent fibre, and hemicellulose was determined by difference. Gross energy was determined on the feed and excreta to calculate AMEn for each ingredient. The corn–soybean meal portion of the basal diet averaged 3,037 kcal AMEn per kg DM, with dextrose having an assumed value of 3,640 kcal per kg DM.

For the six samples of DDGS, AMEn ranged from 2,146 to 3,098 kcal per kg DM, averaging 2,676 kcal per kg DM. The AMEn values for dehydrated corn germ, corn germ meal, HP–DDG, corn gluten meal, corn gluten feed, corn bran and dehulled, degermed corn were 3,308, 1,991, 2,820, 3,182, 1,746, 3,030, and 3,442 kcal per kg DM, respectively.

Stepwise regression resulted in the equation: AMEn, kcal/kg DM = 3,517 + (46.02 × % crude fat, DM basis) – (82.47 × % ash, DM basis) – (33.27 × % hemicellulose, DM basis) (R2=0.89; SEM=191; P<0.01).

These results determined that wide variability exists between corn co-products produced from dry and wet milling plants, and that the best predictors of AMEn are crude fat, ash and hemicellulose.


Rochell S.J., B.J. Kerr and W.A. Dozier, III, 2010. Energy determination of corn co-products fed to broiler chicks from fifteen to 24 days of age and use of composition analysis to predict AMEn. 2010 PSA Annual Meeting, Denver, Colorado. 11 to 15 July 2010.

December 2010

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