Available energy in meat and bone meal as measured by different methods

Area of Science:

• Animal Nutrition
• Poultry Feed Evaluation

Background:

• Meat and bone meal (MBM) is a common protein and energy source in animal diets.
• Accurate estimation of MEn is crucial for formulating balanced and cost-effective poultry rations.

Purpose of the Study:

• To investigate the reasons for lower N-corrected metabolizable energy (MEn) values of MBM at higher dietary substitution levels.
• To determine a more appropriate MEn value for MBM in practical poultry feeding scenarios.

Main Methods:

• Bioassays using different dietary substitution levels (20% vs. 40%) of MBM.
• Comparison of MEn values for simulated MBM and hexane-extracted MBM.
• Nitrogen metabolism studies to assess protein digestibility.

Main Results:

• Significantly higher MEn values were observed at 20% MBM substitution compared to 40%.
• Increasing substitution levels of a simulated MBM did not lower MEn, suggesting factors within MBM itself are involved.
• Hexane-extracted MBM also showed reduced MEn at higher inclusion rates, and reduced protein digestibility was not the cause.

Conclusions:

• The reduced MEn of MBM at higher inclusion rates is not fully explained by fatty acid synergy or decreased protein digestibility.
• Current MEn estimates for MBM may underestimate its energy contribution in practical poultry diets.
• An adjusted MEn value of 2.3–2.5 kcal/g is proposed for MBM in balanced poultry diets.