Nano/microencapsulation of feed additives for ruminal microbiome modulation and enteric methane mitigation in ruminants: a critical review.

Abstract

The latest advances in nutrition, microbiology, and omics sciences are redefining strategies to improve health indices and productivity in livestock. A novel strategy focuses on the deliberate modulation of rumen and intestinal microbiome ecosystems, which, besides being complex, are crucial for animal performance. The use of feed additives, such as bioactive compounds derived from plants and probiotics, has a long tradition supported by their known antioxidant, anti-inflammatory, and antimicrobial properties, among others. However, their practical efficacy is often compromised by their high susceptibility to degradation. Environmental factors such as light, temperature, and harsh conditions like extreme pH and enzymatic and microbiota activity in the gastrointestinal tract of livestock can inactivate these compounds before they reach their site of action to exert the beneficial effects mentioned above. To solve this challenge, nanotechnology, specifically micro- and nanoencapsulation techniques, presents an innovative solution. These strategies can protect bioactive compounds, providing controlled release and targeted delivery to specific absorption sites. This design not only optimizes probiotic survival and bioavailability of bioactive compounds but also facilitates more effective modulation of ruminal and intestinal microbial communities. Recent evidence indicates that this modulation translates into tangible productive benefits, such as better nutrient absorption and higher energy efficiency, positively impacting parameters like milk production. Additionally, these encapsulation techniques improve the efficiency of these bioactive compounds to mitigate enteric methane emissions by altering ruminal fermentation patterns. This review critically analyzes the mechanisms, applications, and potential of encapsulation technologies in ruminant production. Special emphasis is placed on how these delivery systems represent a significant advance toward precision nutrition. Indeed, the efficacy of encapsulation for microbiota manipulation and toxicological challenges for safe and sustainable implementation is discussed. This critical review addresses the following questions: (1) Under what conditions could encapsulation offer real advantages over traditional additives in ruminant livestock? (2) Are there biologically significant differences between nano- and microencapsulation in the ruminal environment? (3) How are changes in the ruminal microbiota translated into productive performance and environmental impact? (4) What is the balance between productive and environmental sustainability benefits versus the toxicological risks of nanomaterials?