|Dozier Iii, William|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2007
Publication Date: 2/19/2008
Citation: Dozier III, W.A., Kerr, B.J., Corzo, A., Kidd, M.T., Weber, T.E., Bregendal, K. 2008. Apparent Metabolizable Energy of Glycerin for Broiler Chickens. Poultry Science. 87:317-322.
Interpretive Summary: Biofuel production is experiencing exponential growth to provide an alternative fuel source to reduce dependence upon petroleum-based fuel products. A co-production from the production of bio-diesel from vegetable oils is crude glycerol. In the United States, annual production capacity of biodiesel is approximately 5.26 billion L/yr, and another 7.15 billion L/yr of additional production through new construction or plant expansion. Glycerin may be a valuable dietary energy source for poultry. 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 poultry feeds is vital. This research demonstrated that the apparent metabolizable energy content of crude glycerol (87% glycerol) was 3,684 kcal/kg for broilers. This information is important for nutritionists at broilers 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: Three energy balance experiments were conducted to determine AMEn of glycerin using broiler chickens (1,104 total birds) of diverse ages. In experiment (Exp.) 1, two dietary treatments were fed from 4 to 11 d of age. Dietary treatments consisted of a control diet (no added glycerin) and a diet containing 6% glycerin (94% control diet + 6% glycerin). Four dietary treatments were provided in Exp. 2 (from 17 to 24 d of age) and 3 (from 38 to 45 d of age). Diets in Exp. 2 and 3 were: 1) control diet (no added glycerin); 2) 3% added glycerin (97% control diet + 3% glycerin); 3) 6% added glycerin (94% control diet + 6% glycerin); 4) 9% added glycerin (91% control diet + 9% glycerin). Diets in Exp. 1 and 2 were identical, but the diet used in Exp. 3 had reduced nutrient levels based on bird age. A single source of glycerin (86.95% glycerin, 9.63% moisture, and 0.29% total fatty acids) was used in all experiments. Feed intake, BW, energy intake, energy excretion, nitrogen intake, nitrogen excretion, AMEn, and AMEn intake were determined in all experiments. In Exp. 1, AMEn determination utilized the difference approach by subtracting AMEn of the control diet from AMEn of the test diet. In Exp. 2 and 3, AMEn intake was regressed against feed intake with the slope estimating AMEn of glycerin. Regression equations were Y = 3,498.99x – 92.37 (P ' 0.0001) and Y = 3,674.77x – 226.53 (P ' 0.0001) for Exp. 2 and 3, respectively. The AMEn of glycerin was determined as 3,877, 3,499, and 3,675 kcal/kg in Exp. 1, 2, and 3, respectively. The average AMEn of glycerin across the three experiments was 3,684 kcal/kg, which is similar to its gross energy (GE) content. These results indicate that AMEn of glycerin is utilized efficiently by broiler chickens, regardless of age.