Soluble lignin and its relation to Klason lignin, acid detergent lignin

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1 Soluble lignin and its relation to Klason lignin, acid detergent lignin and digestibility of NDF Peter J. Van Soest, University James B. Robertson, University Michael C. Barry, AgModels Foundation Prepped Sample ND +Na2SO3 + amylase L and Residue (andr) AD AD Residue (ADR) Acid (H2SO4) ADL ADL Cutin Ash Oxidation (KMNO4) Cutin Ash Ashing 500oC The Detergent Analysis System Sequential Analysis Option 1. Van Soest, 2015 Ash

2 Lignin Assays (Quantitative) Wet chemistry Acetyl Bromide Acid Insoluble Klason Permanganate oxidation TAPPI Van Soest Thermo chemical pygc/fid pymbms TGA Spectroscopy Fluorescence FTIR FT Raman NIR NMR Photoacoustic UV Raman UV vis Visible (image analysis) Lupoi, et.al., 2015 Where: L = KL ADL L = Acid Detergent Soluble Lignin, %DM KL = Klason Lignin, %DM ADL = Acid Detergent Lignin, %DM Lignin Lignin One example of a possible lignin structure. 28 monomers (mostly coniferyl alcohol) C 278 H Lupoi, et.al., Accessed: T12:19:26Z

3 The Data 39 Forages 7 C 3 grasses 17 C 4 grasses 13 maize plants 4 corn silages 15 Legumes 15 alfalfa hays 36 Forages 16 C 3 grasses 8 C 4 grasses 12 Legumes 6 alfalfas 6 other legume species Table 2: Mean values of Klason, acid detergent lignin, L/KL and their ranges. Component N KL ADL L/KL (%) Range L/KL Data Grasses Maize Plants Maize Silage Alfalfa et al. (1997) C 3 Grasses C 4 Grasses Alfalfas Other Legumes KL Klason lignin ADL Acid detergent lignin L/KL Acid detergent soluble lignin divided by Klason lignin (%) KL or L, % DM Figure 1: Relationships of KL and L with ADL for C 3 forages from Van Soest and Robertson and et al. (1997). KL L Linear (KL) Linear ( L) KL = ADL R² = L= ADL R² = ADL, % DM

4 Figure 5: Relationships of KL and L with ADL for C 3 forages from Van Soest and Robertson and et al. (1997) Two perspectives. Figure 2: Relation of acid detergent soluble lignin as a percent of Klason lignin with acid detergent lignin as a percent of dry matter. Combined data for forage grasses from Robertson () and et al Distribution of ADL and L in KL 20 Distribution of ADL and L in KL 80 L/KL = ADL R² = ADL and L, %DM ADL and L, %DM L/KL, % L/KL = ADL R² = Linear () KL, % DM ADL L KL, % DM L ADL Linear () ADL, % DM L/KL, % Figure 3: Relation of acid detergent soluble lignin as a percent of Klason lignin with acid detergent lignin as a percent of dry matter for C 4 mature plants. Combined data from Robertson () and et al 1997 n25. L/KL = ADL R² = L/KL = ADL R² = ADL, % DM Linear () Linear () Linear (ALL) ALL L/KL = ADL R² = Table 3: Correlation between acid detergent soluble lignin expressed as percentage of Klason Lignin ( L/KL) with acid detergent lignin (ADL) on a dry matter basis and with in vitro digestibility of neutral detergent fiber (NDFD48). Forage Class N L/KL * ADL L/KL * NDFD48 ADL * NDFD48 Grasses * * 0.95 ** Maize Plants ** ** Alfalfas * C 3 Grasses ** ** 0.79 ** C 4 Grasses * 0.59 Legumes ** * 0.69 * All Legumes Combined * **

5 Figure 4: Relation between the in vitro digestibility of NDF (NDFD48) with aciddetergent soluble lignin as a percent of Klason lignin ( L/KL). Combined data for forage grasses (n=23). Linear () Linear () Linear (ALL) NDFD48 = ( L/KL) R² = Conclusions Klason Lignin is a heterogeneous mix KL = L + ADL L is soluble in the rumen but is unfermentable NDFD ALL NDFD48 = 0.615( L/KL) NDFD48 = ( L/KL) R² = R² = L/KL, % L dilutes energy of solubles L has no effect on NDFD ADL (insoluble) is the main factor limiting NDFD Proposed Collaborative Fiber Study? Standard reference forages 12 each of: Corn Silage Alfalfa Grass Multiple Sites USDFRC Miner Texas A&M Analyses NDFom ADFom ADL Klason Acetyl Bromide Lignin undf48 undf240 Spectral Scans of all samples & filtrates UV NIR MIR?

6 The objectives of statistical efficiency and mechanistic understanding are sometimes incompatible. Peter J. Van Soest, Nutritional Ecology ot the Ruminant, 2 nd Edition. Then again, sometimes not. Shameless Plug Thank You Available NOW from CALS Contact Heather Darrow for details

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