Enhancing Agricultural Sustainability by Improving the Efficiency of Lignocellulosic Biomass Utilization in the Ruminant Diet via Solid-State Fermentation with White-Rot Fungi: A Review

Abstract

Against the backdrop of the green circular economy, the exploration of reliable and sustainable applications of lignocellulosic biomass (LCBM) has emerged as a critical research frontier. The utilization of LCBM as a ruminant roughage source offers a promising strategy to address two pressing issues: the "human-animal competition for food" dilemma and the environmental degradation resulting from improper LCBM disposal. However, the high degree of lignification in LCBM significantly restricts its utilization efficiency in ruminant diets. In recent years, microbial pretreatment has gained considerable attention as a viable approach to reduce lignification prior to LCBM application as ruminant feed. White-rot fungi (WRF) have emerged as particularly noteworthy among various microbial agents due to their environmentally benign characteristics and unique lignin degradation selectivity. WRF demonstrates remarkable efficacy in enzymatically breaking down the rigid lignocellulosic matrix (comprising lignin, cellulose, and hemicellulose) within LCBM cell walls, thereby reducing lignin content-a largely indigestible component for ruminants-while simultaneously enhancing the nutritional profile through increased protein availability and improved digestibility. Solid-state fermentation mediated by WRF enhances LCBM utilization rates and optimizes its nutritional value for ruminant consumption, thereby contributing to the advancement of sustainable livestock production, agroforestry systems, and global environmental conservation efforts. This review systematically examines recent technological advancements in WRF-mediated solid-state fermentation of LCBM, evaluates its outcomes of nutritional enhancement and animal utilization efficiency, and critically assesses current limitations and future prospects of this innovative approach within the framework of circular bioeconomy principles.

Keywords: agricultural by-products; livestock production; preprocessing; roughage ingredients; ruminant ration.

Figure 2

Comparison of nutritive value, nutrient index, and rumen degradation parameters of several LCBM with alfalfa and oat hay [25,26,27,28,29,30]. (A) Reported chemical composition of LCBM, alfalfa hay, and oat hay (calculations based on research data); (B) Forage quality indices of LCBM, alfalfa hay, and oat hay (calculations based on research data; calculation formula reference [31,32]); (C) In situ rumen degradation parameters for LCBM and nutrients in alfalfa hay (%); a, immediately degradation at time (%); b, potentially degradable fraction (%); ED, effective degradability (%); DM, dry matter; OM, organic matter; HC, hemicellulose; CL, cellulose.

Figure 1

Basic guidelines and approximate flow of LCBM for solid-state fermentation using WRF. (A) Distribution of countries studied on solid-state fermentation of LCBM using white-rot fungi, 2000–2025; (B) Keyword co-occurrence map of studies on solid-state fermentation of LCBM using white-rot fungi, 2000–2025; (C) Basic principles of solid-state fermentation of LCBM using white-rot fungi.