Comparative study of some analytical methods to quantify lignin concentration in tropical grasses

Area of Science:

• Plant biochemistry
• Animal nutrition
• Forage quality assessment

Background:

• Lignin content significantly impacts the degradation of structural carbohydrates in plant cell walls.
• Accurate lignin quantification is essential for understanding its role in tropical forage digestibility.
• Variability in results from different lignin assays necessitates comparative studies.

Purpose of the Study:

• To compare the accuracy of four commercial lignin determination methods (ADL, KL, ABL, PerL) in tropical grasses.
• To assess the relationship between lignin concentration and in vitro degradability across different species and maturity stages.
• To identify the most suitable method for routine lignin analysis in tropical forages.

Main Methods:

• Five tropical grass species were analyzed at five maturity stages.
• Lignin content was determined using Acid Detergent Lignin (ADL), Klason Lignin (KL), Acetyl Bromide Lignin (ABL), and Permanganate Lignin (PerL) assays.
• Lignin concentrations were correlated with in vitro degradability data.

Main Results:

• Maturity, lignin determination method, and their interaction significantly affected lignin content.
• ADL, KL, and ABL methods showed similar negative correlations with forage degradability.
• The PerL method demonstrated unreliability in estimating tropical grass degradability, likely due to interfering compounds.

Conclusions:

• The ADL and KL methods are time-consuming and costly due to the need for ash and nitrogen content correction.
• The Acetyl Bromide Lignin (ABL) method is a rapid, convenient, and reliable alternative for total lignin determination in plants.
• ABL is recommended as a suitable method for routine laboratory analysis of lignin in tropical forages.