Ruminal Digestibility and In-Vitro Methane Emissions of Native Plant Species in Subtropical Rangelands

Enteric methane (CH4) emissions from livestock represent a significant agricultural source of greenhouse gas worldwide. The aim of this study was to determine the effect of plant species and season on nutritional value and methanogenic potential of Florida native rangelands. Treatments consisted of a 4 x 2 factorial arrangement of plant species (creeping bluestem [Schizachyrium scoparium var. stoloniferum {Nash} Wipff], lopsided Indiangrass [Sorghastrum secundum {Elliott} Nash], maidencane [Panicum hemitomon Schult.], and saw-palmetto [Serenoa repens {W. Bartram} Small]) and season (summer or autumn) distributed in a randomized complete block design with four replicates. Samples were analyzed for crude protein (CP), neutral detergent fiber, in-vitro CH4 production, and in-situ ruminal digestibility. The greatest digestive matter (DM) effective degradability was observed in the summer for creeping bluestem (422 g kg(-1)), followed by lopsided Indiangrass (379 g kg(-1)), maidencane (380 g kg(-1)), and saw-palmetto (250 g kg(-1)). The DM effective degradability decreased from summer to autumn for all species, except saw-palmetto. Maidencane had the greatest CP effective degradability in the summer (491 g kg(-1)), followed by lopsided Indiangrass (350 g kg(-1)), creeping bluestem (279 g kg(-1)), and saw-palmetto (170 g kg(-1)); however, lopsided Indiangrass and maidencane decreased CP effective degradability from summer to autumn. There was no difference in CH4 production among creeping lopsided Indiangrass and maidencane (mean of 7 mg g(-1) DM), and saw-palmetto had the least CH4 emissions (2 mg g(-1) DM). Grazing lopsided Indiangrass and maidencane in the summer was an effective strategy to optimize the use of native plant species with greater nutrient digestibility than autumn. Management practices intended to increase rangeland productivity, and the proportion of native grass species relative to saw-palmetto are expected to increase CH4 production. Further research is warranted to evaluate the impacts on rangeland management on animal performance and greenhouse gas balance. (C) 2022 The Society for Range Management. Published by Elsevier Inc. All rights reserved.