Microencapsulation Strategies in Veterinary Medicine: Overcoming Gastrointestinal Barriers in Monogastric and Ruminant Species.

Oral delivery of bioactive compounds in veterinary medicine offers important opportunities to improve animal health, productivity, and welfare, but its effectiveness is often limited by species-specific gastrointestinal physiology. This review aims to provide a comprehensive overview of microencapsulation strategies for oral veterinary delivery, focusing on species-specific gastrointestinal barriers and the formulation approaches developed to overcome them. Monogastric and ruminant animals present distinct gastrointestinal environments that compromise the stability, bioavailability, and therapeutic performance of orally administered compounds. In monogastrics, gastric acidity, digestive enzymes, gastrointestinal transit, and microbiota-mediated interactions represent major barriers, whereas in ruminants, ruminal fermentation, prolonged retention, and physicochemical conditions may cause premature degradation of bioactive compounds. These barriers significantly hinder the successful use of probiotics, enzymes, essential oils, nutrients, vaccines, and veterinary drugs. However, microencapsulation has emerged as a promising solution, providing a protective barrier that improves compound stability, enhances gastrointestinal survival, and enables controlled or site-specific release. By preserving bioactivity and modulating release kinetics, microencapsulation contributes to improved delivery efficiency and functional performance. A distinctive feature of this review is the integration of species-specific gastrointestinal physiology with microencapsulation technologies to provide a rational framework for designing oral delivery systems in veterinary medicine, rather than focusing solely on individual encapsulation technologies. Current challenges related to material selection, formulation optimisation, and industrial scalability are discussed. Overall, this review highlights that integrating gastrointestinal physiology with advanced microencapsulation technologies is essential for developing effective, targeted, and sustainable oral delivery systems, ultimately supporting improved animal health, productivity, and welfare.