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Alkali-Labile Cell-Wall Phenolics and Forage Quality in Switchgrasses selected for Differing Digestibility

Author:
Gabrielsen, B. C., Vogel, K. P., Anderson, B. E., Ward, J. K.
Source:
Crop science 1990 v.30 no.6 pp. 1313
ISSN:
0011-183X
Subject:
Panicum virgatum, strains, strain differences, crop quality, forage, in vitro digestibility, nutritive value, chemical composition, phenolic compounds, fiber content, lignin, crude protein, grazing
Abstract:
Alkali-labile cell-wall phenolics have been implicated in previous research as factors that affect forage digestibility by ruminants. Alkali-labile cell-wall phenolics, in vitro dry matter digestibility (IVDMD), neutral-detergent fiber (NDF), acid-detergent fiber (ADF), lignin (permanganate-oxidation), and crude protein (CP) were determined in three switchgrass (L.) strains differing genetically for IVDMD to determine relationships between these quality parameters and IVDMD during the grazing season. Grazed (upper 1/3 of grazed plants) and ungrazed (whole plants in caged exclosures) forage was collected weekly from replicated 0.4− ha pastures of ‘Trailblazer’ (high IVDMD), ‘Pathfinder’, and a low-IVDMD strain during three grazing seasons from 1983 to 1985. The principal alkali-labile phenolics (g kg NDF) detected were -coumaric acid (PCA) and ferulic acid (FA). Increased PCA concentration due to increased maturity averaged >70% during each grazing season and corresponded with increased NDF, ADF, and lignin and decreased IVDMD, CP, and FA/PCA ratio. Ferulic acid concentration either declined slightly or remained unchanged. Averaged across 3 yr, Trailblazer had higher (< 0.06) IVDMD, lower (< 0.09) PCA and higher (< 0.10) FA/PCA ratio than a divergently selected low-IVDMD strain. Differences between strains in detergent-fiber constituents, FA, and CP were either not apparent or inconsistent with strain differences in IVDMD. Results were consistent with both grazed and ungrazed switchgrass and indicate that alkali-labile cell-wall phenolic composition in switchgrass is heritable and genetically correlated to IVDMD.
Agid:
27413
Handle:
10113/27413