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Evaluation of the metabolizable energy of soybean meal in poultry diets

Glende, J., P. Utterback, M. Cristobal, J. Emmert and C. Parsons
2024

The objective of this study was to reevaluate the metabolizable energy (ME) of dehulled solvent extracted soybean meal (SBM) for poultry diets. Experiment 1 was a precision-fed rooster assay to determine TMEn of 4 SBM. Single Comb White Leghorn roosters were fasted for 26 hours and then were crop intubated with 25 to 30 grams of a SBM sample and excreta were collected quantitatively for 48 hours post feeding. Excreta were freeze-dried and analyzed for gross energy and nitrogen. In Experiment 2, AMEn of the same 4 SBM was determined using commercial broiler chickens. A nutritionally complete corn- SBM basal diet was fed from 0 to 17 days of age. Five diets consisting of 100% basal diet or 70% basal diet and 30% test SBM were then fed from 17 to 21 days of age, and titanium dioxide was used as a digesta marker. The AMEn of the diets was determined, and the AMEn of the SBM was calculated by difference. Experiment 3 was another precision-fed rooster assay to determine TMEn of 17 SBM using the same procedures described above. In addition to the SBM, 2-5 corn samples were included in each experiment so that TMEn and AMEn of the SBM could be compared relative to corn. In the rooster assays (Experiments 1 and 3), 10 individually caged roosters were assigned to each SBM or corn. In the AMEn assay (Experiment 2), 12 replicate pens of 5 chicks were assigned to each dietary treatment. Data were analyzed by ANOVA for completely randomized designs for all experiments, and significance of differences among TMEn and AMEn values within experiments was determined at P < 0.05. In Experiment 1, mean TMEn of the 4 SBM was 3,076 kcal/kg DM with a range of 3,044 to 3,122. Mean AMEn of the 4 SBM in Experiment 2 was 2,843 kcal/kg DM with a range of 2,509 to 3,045. In Experiment 3, mean crude protein and fat for the 17 SBM were 47.1 and 1.5%, respectively, on an 88% DM basis. Mean TMEn of the 17 SBM was 3,000 kcal/kg DM with a range of 2,796 to 3,196 in Experiment 3. There were significant differences (P < 0.05) among TMEn and AMEn values for several SBM within each experiment.

When comparing TMEn and AMEn of SBM relative to corn for all 3 experiments, results indicated that ME of SBM was approximately 73-74% of corn. The ME values, particularly TMEn values, of SBM were higher than table values of the poultry NRC (1994). Thus, results of this study suggest that the ME of SBM for poultry may be higher than previously thought.