Correlations of Phenolic Acids and Xylose Content of Cell Wall with In Vitro Dry Matter Digestibility of Three Maturing Grasses

Maturing reed canarygrass, Russian wildrye, and smooth bromegrass cell walls were analyzed for lignin, phenolic acids, and neutral sugars. Linear correlation between in vitro dry matter digestibility and the p-coumaric acid content was −.86. The correlation between in vitro dry matter digestibility and ratio of p-coumaric to ferulic acid was −.84. Samples with high percentages of lignin also contained high ratios of p-coumaric to ferulic acid. Thus, p-coumaric acid may be more important than ferulic acid in crosslinking lignin to structural carbohydrates. Percent xylose and in vitro dry matter digestibility also were correlated significantly in all three species. A Russian wildrye regrowth sample contained a relatively high percentage of lignin despite its immature appearance. The lower digestibility of that regrowth sample may have resulted both from its high lignin content as well as branched xylans in the hemicellulosic fraction.