|Lammers, P - IOWA STATE UNIVERSITY|
|Honeyman, M - IOWA STATE UNIVERSITY|
|Stalder, K - IOWA STATE UNIVERSITY|
|Dozier Iii, William|
|Kidd, M - MISSISSIPPI STATE UNIV|
|Bregendahl, K - IOWA STATE UNIVERSITY|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 4, 2007
Publication Date: January 7, 2008
Citation: Lammers, P.J., Kerr, B.J., Honeyman, M.S., Stalder, K., Dozier III, W.A., Weber, T.E., Kidd, M.T., Bregendahl, K. 2008. Nitrogen-Corrected Apparent Metabolizable Energy Value of Crude Glycerol for Laying Hens. Poultry Science. 87:104-107. Interpretive Summary: A co-production from the production of bio-diesel from vegetable oils is crude glycerol. With the rapid expension of the bio-diesel industry (www.nbb.org), there will likely be substantial amounts of crude glycerol that may become available for use as a livestock feedstuff. Because glycerol is a precursor to glucose via gluconeogenesis, is an intermediate in lipid production, and yields energy through the glycolytic and tricarboxylic acid pathways, determination of the energy value of crude glycerol in livestock feeds is vital. This research demonstrated that the apparent metabolizable energy content of crude glycerol (87% glycerol) was 3,805 kcal/kg for laying hens. This information is important for nutritionists at universities, feed companies, and laying-hen operations, for the determination of the energy value of crude glycerol for use in feed formulations and provides a basis from which to assess its economic value.
Technical Abstract: An experiment was conducted with laying hens to determine the AMEn value of crude glycerol, a co-product of biodiesel production. Crude glycerol (87% glycerol, 9% water, 0.03% methanol, 1.26% Na, and 3,625 kcal/kg gross energy) was obtained from a commercial biodiesel production facility (Ag Processing Inc., Sergeant Bluff, IA). A total of 48 40-week old laying hens (Hy-Line W-36) were placed in metabolic cages (two hens/cage) and given free access to the experimental diets. A corn and soybean meal–based basal diet (18% CP, 2,875 kcal/kg AMEn, 4.51% Ca, 0.51% non-phytate P) was formulated with 15% glucose•H2O and 1% Celite. Four dietary treatments were created by substituting 0, 5, 10, or 15% crude glycerol for glucose•H2O (3,640 kcal/kg AMEn). After seven days of dietary adaptation, excreta were collected twice daily for three days, freeze-dried, and analyzed for contents of DM, Kjeldahl N, acid-insoluble ash, and gross energy. Egg production was recorded daily, and eggs were collected on days seven and eight of the experiment for calculation of egg mass (egg production x egg weight). Feed consumption was measured over the ten-day experimental period. Egg-production data were analyzed by ANOVA with four treatments and six replications in a completely randomized experimental design. The AMEn value of crude glycerol was estimated as the slope of the linear relationship between the inclusion rate of dietary crude glycerol and the glucose-corrected AMEn value of the experimental diets. No treatment effects (P > 0.1) were apparent for egg-production rate (93.0%), egg weight (56.1 g), egg mass (52.2 g/d), or feed consumption (104 g/d). Linear regression analysis (P < 0.001, r2 = 0.92, n = 24) revealed that the AMEn value of the crude glycerol used in this study was 3,805 ± 238 kcal/kg (mean ± SEM; as-is basis) for laying hens.