Polystyrene Nanoplastics Exposure Alters Gut Microbiota and Correlates with Egg Quality Parameters in Chickens

NPs have become a concerning global environmental problem. Dietary exposure to NPs can cause microbial dysbiosis. However, the risks of NPs to animals, particularly poultry species such as chickens, remain poorly understood. In this study, chickens were continuously exposed to 100 nm NPs via dietary inclusion from 18 weeks of age for 120 days to evaluate the effects of NPs on intestinal health. We found that NPs accumulated in chicken intestinal tissues, leading to adverse alterations in the intestinal mucosal structure, such as villus atrophy and goblet cell depletion, and significantly altering intestinal length. The 16S rRNA sequencing revealed significant gut microbiota dysbiosis, characterized by a loss of diversity and shifts in key bacterial groups. Functional predictions of the microbiota revealed impairments in metabolic pathways, especially carbohydrate and amino acid metabolism. Furthermore, network analysis showed that microbial interactions were disrupted and key functional hubs were lost. Most importantly, NPs exposure led to a significant decline in egg quality parameters, including eggshell thickness and strength, yolk color, weight, shape index, and Haugh units. Correlation analyses connected specific taxa, such as <i>Methanobrevibacter</i>, <i>Rikenellaceae_RC9_gut_group</i>, and <i>Prevotellaceae_UCG-001</i>, to intestinal damage and declines in egg quality. These findings provide a scientific basis for assessing the health risks of NPs in animals and offer insights into the development of gut health interventions.