Evaluation of Various Lignin Assays for Determining Ruminal Digestion of Roughages by Lambs

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Abstract
Six lambs (30 kg) with permanent abomasal cannulae were used in a replicated 3 × 3 Latin square design (1) to evaluate the ultraviolet absorbance of phenolic components in lignin as a marker for partitioning ruminal and post ruminal organic matter digestion (OMD) and (2) to assess the effects of analytical method and marker recovery on interpretation of digesta flow measurements using the lignin ratio technique. Lambs were fed semipurified diets containing Kenhy tall fescue hay (KTF), corn cobs (CC) or cottonseed hulls (CSH), Apparent ruminal OMD was calculated by reference to marker concentration ratios in feed and abomasal OM using chromic oxide (Cr2O3); permanganate (KMnQ4) lignin, acid detergent lignin (ADL) and acetyl bromide soluble lignin (ABSL). Across all diets, fecal recovery of Cr203, KMn04 lignin, ADL and ABSL differed (P<,05), averaging 97.5, 78.0, 78.4 and 65.0%, respectively. Coefficients of apparent ruminal OMD were highly variable (CV = 22%) and each marker ranked dietary treatments differently, reflecting marker x diet interaction (P<.05). Coefficients of ruminal OMD corrected to represent 100% marker recovery at the abo-masum were less variable (CV = 12%) than those based on incomplete recovery, and all markers ranked dietary treatments similarly. Across all diets, corrected estimates of ruminal OMD by reference to Cr203, ADL and KMn04 lignin did not differ (P>.05), but ABSL overestimated (P<.05) extent of ruminal OMD compared to the other marker systems. Results demonstrate that choice of analytical method and extent of recovery may drastically affect the interpretation of digesta flow measurements calculated by reference to lignin. Spectrophoto metric analysis of phenolic components in lignin as ABSL offered no improvement over gravimetric methods; nevertheless, meaningful comparative data were obtained using this marker. Copyright © 1982. American Society of Animal Science . Copyright 1982 by American Society of Animal Science

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