Energy determination of corn co-products fed to broiler chicks from 15 to 24 days of age, and use of composition analysis to predict nitrogen-corrected apparent metabolizable energy

An experiment (3 trials) was conducted to determine the AMEn of 15 corn co-products obtained from various wet and dry milling plants, and to develop prediction equations for AMEn based on chemical composition. Co-products included distillers dried grains with solubles (DDGS, n = 6), high-protein distillers dried grains (n = 2), corn germ (n = 2), corn germ meal, corn bran with solubles, corn gluten meal, corn gluten feed, and dehulled, degermed corn. Treatments (15) consisted of 85% inclusion of the corn-soybean meal basal diet combined with a 15% inclusion of each corn co-product, as well as a control diet containing glucose•H2O (15%) at the expense of the co-product. In each trial, Ross x Ross 708 chicks (10 birds per pen) were randomly assigned to 16 dietary treatments (12 replicate pens; 4 replicate pens per trial). After a 7-d diet acclimation period from 15 to 22 d of age, a 48-h total excreta collection was conducted for the determination of AMEn. Co-products were analyzed for gross energy, CP, moisture, crude fat, starch, crude fiber, ash, total dietary fiber, neutral detergent fiber, and acid detergent fiber, and hemicellulose was determined by difference. Stepwise regression resulted in the following equation: AMEn, kcal/kg of DM = 3,517 + (46.02 x % crude fat, DM basis) – (82.47 x % ash, DM basis) – (33.27 x % hemicellulose, DM basis) (R2 = 0.89; SEM = 191; P ≤ 0.01). Removing hemicellulose from the model resulted in the following equation: AMEn, kcal/kg of DM = (–30.19 x % neutral detergent fiber, DM basis) + (0.81 x gross energy, kcal/kg of DM basis) – (12.26 x % CP, DM basis) (R2 = 0.87; SEM = 196; P ≤ 0.01). These results indicate that nutrient composition may be used to generate AMEn prediction equations for corn co-products fed to broiler chicks.