Components of Forage Quality in Sericea Lespedeza in Relationship to Strain, Season, and Cutting Treatments1
- W. A. Cope and
- J. C. Burns2
A study of forage quality was made on three genetically different strains of sericea [Lespedeza cuneata (Dumont) G. Don]. The study was designed to evaluate forage samples over a wide range of plant maturity, since previous studies have been restricted largely to mature hay samples representing a narrow range. The forage sampling plan covered two distinctly different growth periods, early spring and mid-summer. The three sericea strains were harvested at weekly intervals for short periods during the spring and summer of 1970 and 1971. Leaf and stem portions were separated and placed in liquid nitrogen in the field. Forage quality was evaluated by in vitro dry matter disappearance (IVDMD), by concentrations of total fiber and fiber components, and by concentration of the anti-quality component, tannin. Forage quality, as measured by IVDMD, was generally low, especially for leaf samples high in tannin and stem samples from the more mature growth stages. A low-tannin strain averaged higher in IVDMD than two high-tannin strains over all harvests. Leaf IVDMD was sharply depressed as tannin values approached 10% and then declined slowly with increasing concentrations. Leaf fiber had little direct effect on IVDMD at high tannin levels. IVDMD of stem samples decreased rapidly with successive harvests in both spring and summer. Fiber content was high at an early growth stage for both spring and summer harvest periods. The correlation of fiber content with IVDMD was high and negative. There were only small strain differences in fiber content. Stem tannin content for the summer harvest in 1971 was high enough to affect IVDMD and interacted with fiber content to give very low values. For stem samples from the first harvest period, simple regression of fiber on IVDMD accounted for a significant proportion of the variation in IVDMD (r2 = 0.81 and 0.84, respectively, for neutral detergent fiber and acid detergent fiber. For the second harvest period, the addition of tannin in multiple regression equations increased the predictability to R2 = 0.95 and 0.94, respectively. Neither the simple nor the multiple regressions accounted for a large proportion of the variation in leaf IVDMD.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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