Impact of Microplastics on Livestock: Sources, Exposure Pathways, and Physiological Consequences

Microplastic (MP) contamination has emerged as an escalating environmental hazard with profound implications for terrestrial ecosystems, particularly within livestock-based agricultural systems. The pervasive presence of MPs in soil, water, and feed resources poses significant risks to animal health, food safety, and agricultural sustainability. This review explores the increasing vulnerability of livestock animals to MP exposure, focusing on environmental sources, exposure pathways, and associated physiological impacts. Livestock are regularly exposed to MPs via polluted feed, forage, drinking water, and soils altered with sewage sludge. MP intake, retention, and systemic distribution are influenced by species-specific changes in digestive physiology, notably those between ruminants and monogastric animals. Once internalized, MPs may cause gastrointestinal damage, oxidative stress, immunological dysfunction, hepatic impairment, and possible reproductive harm. Furthermore, microplastics (MPs) act as vectors for hazardous co-contaminants, including heavy metals and persistent organic pollutants, thereby enhancing the risk of bioaccumulation in edible tissues and posing significant challenges to food safety. Chronic exposure to MPs may impair animal health, productivity, and reproductive function, providing greater problems to livestock sustainability, economic viability, and human health. This review highlights the critical need for interdisciplinary research that combines veterinary toxicology, environmental science, and food safety to understand MP toxicokinetic in cattle better and influence evidence-based risk reduction and regulatory regimes.