Physicochemical Characteristics, In Vitro Ruminal Digestibility, Bioactive Compounds, and Estimated Methane...

Pasture plants can contribute to ruminant nutrition and may, depending on composition, influence rumen fermentation and methane production. This study evaluated the nutritional composition, bioactive compounds, and methane production potential of 32 terrestrial plant species commonly foraged by goats in Malta. Dried plant samples were analysed for proximate composition using near-infrared spectroscopy, total polyphenols using the Folin-Ciocalteu assay, antioxidant activity using the DPPH assay, and methane production using an in vitro rumen fermentation system incubated for 48 h, with rumen fluid pooled from three goats (analyses performed in triplicate). Crude protein ranged from 1.16 to 31.97% DM, neutral detergent fibre from 12.29 to 48.89%, and ash from 9.69 to 17.20% across species. Total polyphenolic content varied from 0.07 to 1.30% (w/w), while antioxidant activity (IC₅₀) ranged from 0.37 to 55.9 mg/mL. Methane production after 48 h ranged from 30.39 to 198.26 L CH₄ kg^-1, indicating variation in fermentation characteristics among species. These results indicate that Rumex bucephalophorus and Urtica pilulifera demonstrated relatively high protein or bioactive values and comparatively lower in vitro methane-related parameters under the conditions tested.