PS11-20. Influence of Cultivar on Potential Activity of Methane Production from Annual Ryegrass.

Abstract

Methane (CH4) is a potent greenhouse gas produced during ruminal fermentation, and forage characteristics are key drivers of enteric methane yield in ruminant animals. Annual ryegrass (Lolium perenne L. spp. Multiflorum [Lam.] Husnot) is commonly used in pasture-based livestock systems because of its adaptability, rapid growth, and forage value; however, information on how varietal differences affect the potential activity of methane production (PAMP) remains limited. Therefore, this study evaluated PAMP across 44 annual ryegrass varieties to identify their Varietal differences and their contributions to sustainable livestock production. Ryegrass samples were obtained from the Official Variety Trials at Auburn University in the 2022 and 2023 growing season. Samples were dried and ground to pass through a 2-mm screen and composited by variety across harvest. Samples were incubated for 3 h with buffered rumen fluid under anaerobic conditions at 39 °C and then stored at 4 °C to stop fermentation and until further analysis. Methane concentrations were determined by gas chromatography; There was an effect of variety on methane production potential (P < 0.01). Green Dragon, GrazeKeeper, RANAHAN, and Mantis showed the greatest methane production potential values, ranging from approximately 60 to 69 mM/g, whereas FrostProof, Bruiser, and Rival showed the lowest values, with values below 30 mM/g. The other varieties ranged from 30 to 60 mM/g. Overall, this study highlights the importance of considering forage varietal differences when evaluating both animal performance and environmental sustainability. Identifying specific varieties associated with less effect on methane production may help to support forage selection for sustainable livestock systems. Future research should evaluate these methane responses in relation to forage nutritive value and animal performance.