Moisture and Ash Determination in Animal Feed (TGA801)

Significance of the Topic

The precise measurement of moisture and ash in animal feed is critical for ensuring product quality, safety, and nutritional consistency. Moisture content affects texture, taste, and microbial stability, while ash content reflects the total mineral fraction and supports accurate dry-basis calculations, purity assessment, and yield determination.

Objectives and Scope of the Study

This application note demonstrates the use of the LECO TGA801 macro thermogravimetric analyzer to perform simultaneous moisture and ash determinations on representative animal feed samples. The study follows modified AOAC Official Methods 930.15 and 942.05 to evaluate method precision, repeatability, and throughput for typical feed matrices including alfalfa, corn silage, and distillers grain.

Methodology and Instrumentation

Instrumentation Used:

• LECO TGA801 macro thermogravimetric analyzer with dual furnace capability
• Large ceramic crucibles (621-331) and double-ended scoop (621-011-507)

Sample Preparation and Parameters:

• Sample mass: ~1.0 g (range 0.8–1.2 g)
• Atmosphere: air at 10 L/min flow rate
• Moisture determination: 25 °C to 135 °C at 10 °C/min, hold 30 min until mass constancy (0.0005 g window, 9 min)
• Ash determination: 135 °C to 600 °C at 20 °C/min, hold 30 min until mass constancy
• Total analysis time per batch: ~4 hours for up to 19 samples

Calculations:

• Moisture % = (Initial mass – moisture mass) ÷ Initial mass
• Ash % = (Ash mass ÷ Initial mass)
• Ash dry % = Ash % × (1 ÷ (1 – Moisture fraction))

Main Results and Discussion

Results for three feed types (n=10 each) showed:

• Alfalfa: average moisture 8.07 % (SD 0.05), ash 10.00 % (SD 0.02), ash dry 10.88 % (SD 0.02)
• Corn silage: average moisture 6.92 % (SD 0.07), ash 5.49 % (SD 0.02), ash dry 5.90 % (SD 0.02)
• Distillers grain: average moisture 10.59 % (SD 0.15), ash 4.84 % (SD 0.07), ash dry 5.41 % (SD 0.08)

Low standard deviations across replicates indicate strong precision and reproducibility. The dual-furnace design enabled concurrent analysis of multiple samples, enhancing laboratory throughput. Data align with expected values for these feed matrices, confirming method accuracy.

Benefits and Practical Applications

• Rapid, simultaneous determination of moisture and ash reduces total analysis time and sample handling.
• High throughput capability (up to 19 samples) supports routine QA/QC in feed production facilities and research labs.
• Automated temperature ramps and hold steps minimize operator intervention and improve data consistency.
• Applicable to a wide range of feed types and customizable to other agricultural or food matrices.

Future Trends and Potential Applications

Emerging developments may include integration of TGA data with laboratory information management systems (LIMS) for real-time process control, coupling thermogravimetric analysis with evolved gas analysis for compositional insights, and further miniaturization of instrumentation for field or on-line monitoring. Enhanced software algorithms could enable adaptive heating profiles and predictive quality assurance across diverse sample matrices.

Conclusion

The LECO TGA801 provides a robust, efficient solution for combined moisture and ash determination in animal feed. Its dual-furnace design and automated method parameters ensure high precision, reproducibility, and throughput, making it an ideal tool for industrial and research applications in feed analysis.

References

• AOAC Official Method 930.15. Moisture in Animal Feed.
• AOAC Official Method 942.05. Ash of Animal Feed.