Season Progression, Ontogenesis, and Environment Affect Lespedeza cuneata Herbage Condensed Tannin, Fiber, and Crude Protein Concentrations

Abstract

Sericea lespedeza [Lespedeza cuneata (Dumont de Courset) G. Don., SL] is a perennial, warm‐season forage legume with wide adaptation, freeze tolerance, establishment ease, and persistence under grazing. It has high condensed tannin (CT) concentrations (g kg−1), which could be useful for methane mitigation and rumen bypass protein, as well as insect pest and gastro‐intestinal nematode suppression. However, CT concentration is variable. Our objective was to test CT, crude protein (CP), and fiber concentrations at five locations (Georgia, Alabama, North Carolina, Louisiana, and Texas) during a growing season. Established ‘AU Grazer’ SL regrowth and accumulated herbage in separate trials was sampled starting late April 2010 every 35 d for four dates. Regrowth CP concentration ranged (P ≤ 0.05) from 127 g kg−1 in North Carolina on date 3 up to 221 g kg−1 in Alabama on date 1. Sericea lespedeza regrowth in the warmest latitude (Louisiana) consistently contained among the greatest (P ≤ 0.05) acid detergent fiber. In regrowth herbage, we recorded a wide (P ≤ 0.05) total CT range, from 133.5 mg kg−1 in Texas on date 3 to 46.1 mg kg−1 in Louisiana on date 1, reflecting variability in fiber‐bound, protein‐bound, and especially extractible CT. Results from accumulated herbage reflected (P ≤ 0.05) herbage ontogenesis with less CP and greater fiber concentration with maturity but showed the same lack of CT concentration pattern as the regrowth herbage. These results indicate that SL herbage nutritive value and CT concentration is variable, so that any hay or pellets sold commercially for CT content should be assayed by environment and crop maturity.

Harvest regimen changes sericea lespedeza condensed tannin, fiber and protein concentrations

“…In a field study looking at the effect of season progression in repeatedly harvested and accumulated SL herbage, Muir et al . () confirmed that CT concentration in SL varied with edaphoclimatic conditions when measured throughout the season on regrowing or previously unharvested (unstressed) SL. These studies did not, however, compare season‐long harvest regimen effect on SL herbage CT concentration, a key factor in harnessing phenolic biological activity (Naumann et al .…”

“…() found that CT concentrations were associated with maturity (reproduction) while Muir et al . (), with the same cultivar in the field, reported a less predictable pattern with season progression and ontogenesis.…”

“…) raises questions about variable concentration (Muir et al . ) and yield (Muir et al . ) of these polyphenolics with changing harvest regimen and growing environment.…”

“…Muir et al . () compared nutrient concentration changes as the growing season progressed in 35‐day (harvested from the same plants every 35 days) and ACCUM (harvested from previously unclipped plants every 35 days) as two distinct trials. In the current trial, we compared season‐long averages from 35‐day, ACCUM and 40‐cm harvest (clip every time plants reached 40 cm height) regimens as a single experiment.…”

Benefits of Condensed Tannins in Forage Legumes Fed to Ruminants: Importance of Structure, Concentration, and Diet Composition

“…Both concentration and composition can change with season Grabber et al, 2015;Muir et al, 2017), but accession differences tend to be much larger (Springer et al, 2002;Stringano et al, 2012). Importantly, environment did not affect the ranking of the CT traits of a few sainfoin accessions (i.e., there was no genotype ´ environment interaction) (Azuhnwi et al, 2013a ;Malisch et al, 2016); this demonstrates that there are opportunities for trait-directed breeding of new cultivars.…”