Lignin composition is more important than content for maize stem cell wall degradation.

Area of Science:

• Agricultural Science
• Animal Nutrition
• Biochemistry

Background:

• Investigated the chemical and molecular properties of maize stems, specifically acid detergent lignin (ADL) content and syringyl to guaiacyl (S:G) ratio.
• Examined the relationship between these properties and in vitro gas production to assess maize stem cell wall degradability in ruminants.

Purpose of the Study:

• Determine the relative importance of ADL content and S:G ratio in maize stem cell wall degradation.
• Identify key factors influencing the digestibility of maize in ruminant diets.

Main Methods:

• Harvested different internodes from two maize cultivars (Ambrosini and Aastar) throughout the growing season.
• Analyzed ADL content and S:G ratio in stem tissues.
• Measured in vitro gas production as an indicator of cell wall fermentation and degradation.

Main Results:

• ADL content decreased with higher internode number but fluctuated seasonally.
• S:G ratio was lower in younger tissues (higher internode number or earlier harvest).
• S:G ratio showed a stronger correlation (R² = 0.80) with early-stage gas production (3-20 h) than ADL content (R² = 0.68).

Conclusions:

• The S:G ratio is a more dominant factor than ADL content in maize stem cell wall degradation.
• Understanding S:G ratio is crucial for predicting and improving the degradability of maize-based ruminant feeds.