Relationship between processing score and kernel-fraction particle size in whole-plant corn silage

Area of Science:

• Animal Science
• Agronomy
• Feed Science

Background:

• Kernel processing in whole-plant corn silage (WPCS) is crucial for enhancing starch digestibility.
• The corn silage processing score (CSPS) is a common metric, but its effectiveness in fully describing kernel breakage is debated.
• The geometric mean particle size (GMPS) of the kernel fraction requires further investigation for WPCS quality assessment.

Purpose of the Study:

• To evaluate the impact of varied kernel particle sizes on digestibility.
• To establish a method for measuring the GMPS of WPCS kernels.
• To assess the relationship between CSPS and the GMPS of the kernel fraction in WPCS.

Main Methods:

• Manually cutting dried corn kernels into 2, 4, 8, 16, 32, or 64 pieces to analyze particle size distribution, surface area, and ruminal dry matter (DM) digestibility.
• Utilizing hydrodynamic separation to isolate kernel fractions from WPCS samples (n=80).
• Determining CSPS and measuring GMPS and surface area of the kernel fraction via dry sieving.

Main Results:

• Ruminal DM disappearance of corn kernels increased as particle size decreased, with whole kernels showing the lowest digestibility.
• Linear relationships between CSPS and kernel fraction GMPS/surface area were poor.
• Strong quadratic relationships were found between the proportion of kernel fraction passing through a 4.75-mm screen and kernel fraction GMPS and surface area.

Conclusions:

• Reduced kernel particle size significantly enhances in vitro ruminal DM digestibility.
• Hydrodynamic separation combined with dry sieving to determine GMPS offers a more precise evaluation of kernel processing in WPCS compared to CSPS.
• Optimizing kernel processing requires considering GMPS and surface area for improved silage quality.