This study is a systematic critical review aimed at rigorously evaluating the potential of Hermetia illucens larvae (black soldier fly larvae, BSFL) as a sustainable protein source for animal feed through a standardized methodological framework. To address the significant challenge posed by the increasing global demand for protein feed to agricultural sustainability, we retrieved relevant studies published between October 2008 and June 2025 from three core databases—PubMed, ScienceDirect, and Web of Science—and conducted study screening and data extraction in accordance with the PRISMA guidelines. BSFL represent a viable alternative, with a high protein content of 40–60% and efficient organic waste conversion capabilities. This systematic review explores the potential of BSFL to replace traditional protein sources such as fishmeal and soybean meal in animal feed, highlighting their advantages in enhancing growth performance, improving gut health, and reducing methane emissions in ruminants. However, there are still critical research gaps, including the need for standardized safety assessments regarding heavy metal accumulation and chitin digestibility. Addressing these challenges through optimized rearing techniques and rigorous safety evaluations will be crucial for scaling up BSFL production and advancing the development of circular agriculture.

The rumen microbiome represents a cornerstone of ruminant digestive physiology, orchestrating the anaerobic fermentation of plant biomass into short-chain fatty acids (SCFAs)—critical metabolites underpinning host energy metabolism, immune function, and environmental sustainability. This comprehensive review evaluates the transformative role of pan-genomics in deciphering the genetic and metabolic networks governing SCFA production in the rumen ecosystem. By integrating multi-omics datasets, pan-genomic approaches unveil unprecedented layers of microbial diversity, enabling precise identification of core functional genes and their dynamic contributions to carbohydrate degradation and SCFA biosynthesis. Notable advancements include the following: mechanistic insights into microbial community assembly and metabolic pathway regulation, highlighting strain-specific adaptations to dietary shifts; precision interventions for optimizing feed efficiency, such as rationally designing microbial consortia and screening novel feed additives through pan-genome association studies; and sustainability breakthroughs, demonstrating how targeted modulation of rumen fermentation can simultaneously enhance production efficiency and mitigate methane emissions. This synthesis underscores the potential of pan-genomics to revolutionize ruminant nutrition, offering a blueprint for developing next-generation strategies that reconcile agricultural productivity with environmental stewardship. The translational applications discussed herein position pan-genomics as a critical tool for advancing animal science and fostering a resilient livestock industry.

The valorization of food waste through bioconversion using black soldier fly larvae (BSFL, Hermetia illucens) represents a promising pathway for sustainable waste management. However, the efficiency and safety of this process when using low-quality food waste substrates remain insufficiently characterized. This study investigated the adaptive responses, nutrient conversion efficiency, and product safety of BSFL reared solely on food waste (moisture 78.4%, crude protein 42.98%, pH 3.62) under controlled conditions (28 °C, 55% RH). Larval growth followed a logistic model (R² = 0.96), with an inflection point at 13.14 days and a maximum daily weight gain of 0.0153 g/larva. Crude protein content increased significantly to 64.21%, while crude fat peaked at 26.42% by day 6 before declining. Larvae accumulated essential amino acids and functional fatty acids effectively. Notably, BSFL demonstrated a strong ability to exclude arsenic and chromium, with over 90% of these heavy metals retained in the frass. The frass itself exhibited high organic matter content (up to 61.57%) and an alkaline pH, meeting general standards for organic fertilizers. These findings underscore the resilience of BSFL and its potential for safe, high-value biomass production from challenging food waste streams, contributing to advanced circular economy strategies.

Black soldier fly larvae (Hermetia illucens) (BSFL) are insect larvae with significant ecological and economic value. This study aims to investigate whether swill and manure had any effects on the transcriptome and metabolome of BSFL. Through high-throughput transcriptome sequencing, we found that larvae fed with swill exhibited higher levels of gene expression, especially with the upregulation of genes related to energy metabolism, amino acid metabolism, and redox reactions. Metabolomics analysis showed a significant increase in energy metabolism-related metabolites, such as organic acids and amino acids, in the swill-fed larvae. In contrast, gene expression and metabolic characteristics in the pig manure-fed group indicated a higher stress response, with relevant genes and metabolites (such as short-chain fatty acids and antioxidants) showing significant upregulation. GO and KEGG enrichment analyses further supported these results, suggesting that swill promotes larval growth and metabolism, whereas pig manure induces the activation of stress response mechanisms. These findings offer clear molecular and physiological insights into the optimization of substrate selection for enhancing the performance of BSFL in waste management.

Black soldier flies (Hermetia illucens) are widely used in organic waste bioconversion, and their adaptive capacity to region-specific food waste is critical for efficient application. This study aimed to explore the molecular mechanisms underlying the adaptation of black soldier fly larvae to long-term domestication on regional food waste from Kunming and Qujing. Integrated transcriptomic and metabolomic analyses were performed to identify differences in gene expression and metabolite profiles between the two groups of larvae. The results showed significant divergence in gene expression networks, with key differences in cytochrome P450 detoxification pathways, TOR nutrient-sensing pathways, and zf-C2H2 zinc finger transcription factor families. Metabolomic analysis revealed region-specific metabolic reprogramming, including enhanced branched-chain amino acid degradation in one group and activated sphingolipid signaling pathways with accumulated indole derivatives in the other. Additionally, 13.86% of unannotated metabolites in the metabolome exhibited high connectivity in metabolic networks, suggesting potential roles as “bridge metabolites” in adaptation. These findings demonstrate that long-term domestication on regional food waste drives adaptive differentiation in black soldier fly larvae through regulatory network remodeling, metabolic reprogramming, and activation of hidden metabolic reserves. The study provides a theoretical basis for optimizing the application of black soldier flies in waste treatment and strain breeding and establishes a “substrate-gene-metabolism” multi-omics framework for understanding insect adaptive evolution.

Against the background of the ongoing transition toward green livestock production and the implementation of “dual-carbon” goals, reducing the environmental footprint of ruminant production while maintaining animal performance has become a key focus in nutritional regulation research. This review summarizes and critically discusses the mechanisms and recent progress of nutritional strategies for emission mitigation and improved nutrient utilization in ruminants, with particular emphasis on major environmental challenges, including enteric methane emissions and nitrogen and phosphorus losses. The review discusses the underlying mechanisms through which nutritional interventions contribute to emission reduction, focusing on ruminal hydrogen flux allocation, microbial community remodeling, host metabolic responses, and changes in nutrient utilization efficiency. In addition, by integrating functional feed additives, diet formulation optimization, precision protein supply, and mineral nutrition regulation, this review compares the application characteristics and practical challenges of different strategies in mitigating methane emissions, reducing nutrient excretion, and sustaining production performance. Furthermore, research approaches such as in vitro screening, multi-omics analysis, and evidence synthesis approaches are discussed to highlight the shift of green nutritional technologies from single-target interventions toward integrated and system-level regulation. This review provides a theoretical basis and technical reference for developing green ruminant production systems that balance productivity, animal health, and environmental sustainability.