Forage Quality and Digestion Kinetics of Switchgrass Herbage and Morphological Components

Abstract

As switchgrass (Panicum virgatum L.) matures, whole plant nutritive value declines. In field studies, ‘Cave‐In‐Rock’, ‘Pathfinder’, and ‘Trailblazer’ switchgrass were seeded into a Blount silt loam soil (fine, illitic, mesic Aeric Ochraqualf) to determine the interaction between morphological components and maturation and its impact on forage quality. Herbage was initially harvested when the flag leaf was just visible with subsequent harvests occurring 14 and 28 d later. Cave‐In‐Rock had higher (25 g kg−1) in vitro dry matter disappearance (IVDMD) and lower (35 g kg−1) neutral detergent fiber (NDF) concentrations than the other cultivars (P < 0.05). Leaf blades, which comprised 47% of total forage at the first harvest and 26% at the last harvest, were highest in N concentration, IVDMD, and extent of NDF digestion for all harvest dates. Leaf sheaths and stems had similar N concentrations, but for IVDMD, NDF, lignin, and extent of cell wall digestion, leaf sheath values were intermediate between blades and stems. Lignin concentration of stems between the first and last harvest increased 38.8 g kg−1, while stem IVDMD and extent of stem NDF digestion declined 210 g kg−1 and 228 g kg−1 NDF, respectively. No significant whole plant cultivar differences were found for either rate or 96‐h extent of NDF digestion (P > 0.05). The in vitro rate constant for stem NDF declined 0.024 h−1 with maturation (P < 0.05), while leaf blade and sheath rate constants did not change. These results indicate that changes in the proportion and composition of the stem fraction and composition of the sheath fraction are the major factors causing a decline in switchgrass herbage quality and rate of NDF digestion with maturation.

Nitrogen and harvest management of Conservation Reserve Program (CRP) grassland for sustainable biomass feedstock production

“…The concentration of T‐N has been previously shown to decrease with delayed harvest timing (Clark, ; Griffin & Jung, ; Hayes, ; Twidwell et al ., ). The results reported here show a similar response, as T‐N was shown to decrease with delayed harvest, with the exception of GA.…”

“…The results reported here show a similar response, as T‐N was shown to decrease with delayed harvest, with the exception of GA. Previous reports have suggested a seasonal decline in T‐N (Griffin & Jung, ; Twidwell et al ., ) is possibly due to remobilization of N within the plant to the roots and other storage organs for winter survival (Owensby et al ., ; Vogel et al ., ). The concentration of T‐N was also shown to respond to N‐application; however, this response was site dependent.…”

FORAGE PRODUCTION AND NUTRITIVE VALUE OF (Clitoria ternatea) HARVESTED AT 60, 75 AND 90 DAYS AFTER PLANTING

“…Dibandingkan dengan rumput, leguminosa mempunyai proporsi daun yang lebih tinggi dan menurun dengan penurunan yang lebih lambat ketika tanaman bertambah umur. Sebagai contoh, Twidlell et al (1988) melaporkan bahwa proporsi daun pada rumput menurun dari 47% pada periode vegetatif menjadi 26% pada periode generatif. Sementara dalam penelitian ini, proporsi daun C. ternatea menurun dari 65% pada fase vegetatif menjadi 41% pada fase generatif.…”

High‐density linkage map reveals QTL underlying growth traits in AP13×VS16 biparental population of switchgrass

“…The shift from the vegetative to the reproductive growth signifies the downhill of the biomass accumulation because the photosynthetic products are mostly used to complete the development of reproductive parts. Dry matter digestibility and concentrations of crude protein, ADF (acid detergent fiber), NDF (neutral detergent fiber), and cellulose decline with the maturity of the switchgrass hay (Burns, Pond, Fisher, & Luginbuhl, 1997;Griffin & Jung, 1983;Twidwell, Johnson, Cherney, & Volenec, 1988).…”