An experiment was conducted with laying hens to determine the nitrogen-corrected apparent metabolizable energy AMEn value of crude glycerol, a co-product of biodiesel production. Crude glycerol (87% glycerol, 9% water) was obtained from a commercial biodiesel production facility. A total of 48 40-week-old laying hens (Hy-Line W-36) was placed in metabolic cages (2 hens/cage) and given free access to the experimental diets. A corn and soybean meal–based basal diet was formulated with 15% glucose•H2O. Four dietary treatments were created by substituting 0, 5, 10, or 15% crude glycerol for glucose•H2O (3,640 kcal/kg AMEn). After 7 days of dietary adaptation, excreta were collected twice daily for 3 days, freeze-dried, and analyzed for contents of dry matter, nitrogen, acid-insoluble ash, and gross energy. Egg production was recorded daily, and eggs were collected on days 7 and 8 of the experiment for calculation of egg mass (egg production × egg weight). No significant 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, r 2 = 0.92, n = 24) revealed that the AMEn value of the crude glycerol used in this study was 3,805 kcal/kg (asis basis) for laying hens, slightly higher than that reported for corn grain and less than half of that reported for vegetable oil.
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