Lignin Digestibility by Lambs Fed both Low Quality and High Quality Roughages

Abstract

Trials were conducted with lambs to evaluate the digestibilities of lignins from various plant sources using the acid detergent lignin (ADL) and acetyl bromide soluble lignin (ABSL) assays. Roughages used in the digestion studies included corn cobs, wheat straw, oat middlings, bagasse, solvent-extracted feces, alfalfa, and perennial ryegrass. ADL digestibilities ranged from −79.8% (when lambs were fed solvent-extracted feces from animals previously fed wheat straw) to +27.6% (when lambs were fed corn cobs as the roughage source). ABSL digestibilities did not agree with those obtained by the ADL method with values ranging from −44.4% (corn cob-fed lambs) to + 17.2% (bagasse-fed lambs). When using the ABSL technique to quantitatively determine both soluble and insoluble lignin (residual lignin left after acetyl bromide treatment of a roughage), those roughages that exhibited high soluble lignin absorbances had smaller amounts of lignin solubilized by acetyl bromide than did those which exhibited lower absorbance values. Positive correlations were established between the percentage of lignin solubilized by acetyl bromide and the ABSL absorbances of both low and high quality roughages.