Mechanisms of Action of Plant-Derived Compounds in Animal Nutrition and Their Role in Mitigating Livestock Environmental Emissions

Livestock agriculture faces mounting pressure to reduce its environmental footprint, particularly enteric methane, urinary nitrogen, and ammonia emissions, without compromising animal productivity or feed-use efficiency. Plant-derived bioactive compounds, including condensed tannins, hydrolysable tannins, essential oils, saponins, flavonoids, and polyphenols, have emerged as promising natural feed additives and nutritional strategies in ruminant production systems. However, their responses are often inconsistent and depend on plant source, chemical structure, dietary composition, inclusion level, animal species, and method of delivery. Their wider application has therefore been limited by an incomplete mechanistic understanding: how exactly do these compounds alter rumen fermentation, modify microbial community function, improve nutrient utilization, or shift nitrogen metabolism in ways that translate into measurable reductions in livestock emissions?This Research Topic focuses specifically on the mechanisms through which plant-derived compounds exert their effects in the gastrointestinal tract, with particular emphasis on rumen ecology, fermentation pathways, nitrogen utilization, gut health, and the downstream environmental consequences of these biological responses. The aim is to bring together studies that move beyond simple performance responses and provide clearer mechanistic explanations for how plant bioactive compounds can support sustainable livestock production.Areas of interest include, but are not limited to:• Rumen fermentation and methane mitigation: inhibition of methanogenic archaea, changes in hydrogen balance, modulation of volatile fatty acid profiles, acetate-to-propionate ratio, and protozoa-mediated pathways targeted by saponins and tannins.• Nitrogen metabolism and excretion: tannin–protein binding, reduced ruminal protein degradation, improved microbial protein synthesis, increased intestinal amino acid supply, shifts in urinary versus faecal nitrogen partitioning, and reductions in urease activity and ammonia volatilization.• Gut microbial targets: how specific bioactive compounds selectively suppress or enrich microbial taxa linked to methane production, fiber degradation, protein metabolism, rumen ammonia formation, or inefficient nitrogen use.• Digestibility, feed efficiency, and animal response: effects on dry matter intake, nutrient digestibility, feed conversion efficiency, milk production, growth performance, and productive efficiency in dairy and beef cattle, sheep, goats, buffaloes, and other livestock species.• Molecular and cellular mechanisms: receptor-level interactions, enzyme inhibition, and signalling pathways, including NF-κB, tight junction proteins, oxidative stress responses, inflammatory regulation, epithelial barrier function, and nutrient transport, relevant to digestive efficiency and fermentation output.• Dose response, bioavailability, and delivery systems: how compound structure, feed matrix, rumen stability, encapsulation, slow-release technology, adaptation period, and delivery method govern in vivo efficacy and environmental outcomes.• Environmental measurements and practical implications: studies linking mechanistic nutritional responses with direct or indirect measurements of enteric methane, nitrogen losses, ammonia emissions, manure characteristics, and whole-farm sustainability indicators.We welcome Original Research, Reviews, Mini Reviews, and Perspectives. Methodological papers and studies integrating rumen fermentation, microbiome analysis, metabolomics, animal performance, and environmental measurements are also encouraged. Studies that bridge mechanistic nutritional science with environmental measurement and provide practical implications for sustainable ruminant feeding systems are particularly encouraged. Topic editors: Anusorn Cherdthong, Chaichana Suriyapha, Juan J. Loor Source: https://www.frontiersin.org/research-topics/82351/mechanisms-of-action-of-plant-derived-compounds-in-animal-nutrition-and-their-role-in-mitigating-livestock-environmental-emissions