Polyethylene microplastics impair chicken growth through gut microbiota-induced hepatic fatty acid metabolism dysfunction.

Microplastics (MPs) negatively impact various terrestrial animals, but their comprehensive effects on Gallus gallus domesticus, key agricultural and ecological species connecting people and the environment, are not well-documented. This study investigates the effects of polyethylene (PE) MPs and phthalate esters (PAEs) on chicken growth, liver metabolism, and gut microbiota using multi-omics and 16S rRNA sequencing technology. Results show that PE MPs, particularly those containing PAEs, significantly reduced body weight gain and hepatic triglyceride levels by up to 71.2 % and 50.1 %, respectively (p < 0.05). The clean MPs affected energy metabolism, while PAE-spiked MPs disrupted fatty acid metabolism and triggered immune and inflammatory responses in the liver. Key genes related to fatty acid metabolism such as FAN, SCD and ELOVL5 were significantly downregulated, leading to imbalances in lipid metabolism. These disruptions in PAE-spiked MPs exposure were associated with the altered gut microbiota balance, including increased Firmicutes/Bacteroidetes ratios and changes in Actinobacteriota and Proteobacteria abundance. Totally, the study highlights a "Trojan Horse" effect, where MPs act as carriers for PAEs, intensifying toxicity through gut-liver axis interactions. The findings emphasize the role of gut microbiota in mediating liver dysfunction and impaired growth.