Sustainable Modulation of Rumen Fermentation and Greenhouse Gas Emissions Using Radish Seeds as a Natural Feed Additive

This study investigated the potential of radish seeds as a sustainable feed additive to enhance nutrient utilization and mitigate greenhouse gas emissions in ruminant systems. Five dietary treatments were formulated by supplementing radish seeds at 0, 0.5, 1.0, 1.5, and 2.0% of dietary dry matter (DM) into a basal diet consisting of concentrate feed mixture, berseem hay, and rice straw (5:4:1 ratio). Key parameters evaluated included in vitro nutrient degradability, ruminal fermentation kinetics, gas production (GP), and emissions of methane (CH4) and carbon dioxide. Gas chromatography analysis identified eucalyptol, α-pinene, and β-pinene as the predominant bioactive compounds in radish seeds. Inclusion of radish seeds led to significant linear (p < 0.001) and quadratic (p < 0.001) increases in asymptotic GP, with the highest values observed at 1.5% and 2.0% inclusion levels. Although CH4 production increased with seed supplementation, its rate exhibited a quadratic trend (p = 0.03), reaching a minimum at 1% inclusion. Radish seeds also linearly improved (p < 0.001) the degradability of DM, neutral detergent fiber, and acid detergent fiber. While total short-chain fatty acids (SCFA) and acetate concentrations increased (p = 0.004), propionate and butyrate remained unaffected. Additionally, ammonia-N concentration, microbial protein synthesis, and partitioning factor showed both linear and quadratic responses (p < 0.05 and p < 0.019, respectively). These findings highlight the potential of radish seeds to improve fermentation efficiency and reduce the environmental footprint of ruminant production systems, contributing to more sustainable livestock feeding strategies.