Evaluating the Feasibility of Megathyrsus maximus (Guinea grass) as Fodder at Different Harvesting Intervals.

Abstract

Megathyrsus maximum is an invasive and problematic weed prevalent in various agricultural lands, including coconut plantations. The conventional methods of weed control, such as manual, chemical, and mechanical approaches, prove ineffective against this weed due to its competitive propagation mechanisms and the substantial labor required for weeding. Although Megathyrsus maximum is recognized as a troublesome weed in Sri Lanka, it was initially introduced to the country in the 1820s for use as fodder. Therefore, the objective of this study was to assess the fodder quality of Megathyrsus maximum under local conditions, aiming to utilize it as a beneficial management technique for controlling this weed. The experiment was conducted for five months in an existing guinea grass field, which naturally provided the growth environment. The study followed a randomized complete block design. Plant samples were collected at various growth stages, specifically at 4, 6, 8, 10, and 12 weeks after the initial cutting. Several growth parameters were measured, including plant height, number of leaves, number of tillers, leaf length, leaf-to-petiole ratio, fresh weight of biomass, dry matter yield, and percentage of flowering. The harvested grasses were analyzed for crude protein, crude fiber, and ash contents to assess the availability of nutrients in the leaves for fodder purposes. The results revealed significant differences (P<0.05) in the measured growth and quality parameters at different growth stages. Considering the growth and nutritive parameters of Megathyrsus maximum, it is recommended that the weed be harvested at the 8-week growth stage for optimal utilization as fodder for ruminant animals.