A new laboratory study suggests that microplastics may not simply pass through farm animals. Instead, they appear to interact with the microbial community inside the rumen, the first stomach chamber in cattle where fermentation takes place. The findings add early evidence that plastic particles common in agricultural settings could influence animal health and the broader food chain.
Microplastics have been found in livestock feed, soil, manure and even human stool samples. To better understand what happens once these particles enter an animal’s digestive system, researchers from the University of Helsinki and several European universities used a controlled fermentation system that mimics the cow rumen. They combined rumen fluid with hay or barley and exposed the mixture to five types of microplastics often present in farm environments.
Across all experiments, the particles altered fermentation activity. Researchers saw lower cumulative gas production, a standard measure of microbial function, regardless of plastic type or particle size. Total dry matter disappearance also increased, suggesting that not only feed but some portion of the plastic mass itself may break down into smaller fragments during fermentation.
Certain proteins linked to microbial stress increased in barley-based incubations, while activity related to carbohydrate and amino acid metabolism decreased. The team says the pattern is consistent with a stressed microbial ecosystem.
“Our work is a first step toward understanding the biological consequences of microplastic exposure in farm animals,” said lead researcher Daniel Brugger. “There is an urgent need for in-vivo studies to better understand the impacts on animal health and food safety, especially as global plastic production continues to rise.”
The findings highlight potential implications for animal health and for contamination pathways within agricultural systems. A rumen that is less efficient or more stressed may affect digestion and nutrient use, while smaller particle fragments created during fermentation could be more likely to move into tissues. Scientists say that needs to be investigated in live animals.
“Our study shows for the first time that microplastics do not simply pass through the digestive tract of farm animals,” said Jana Seifert. “This means farm animals are not passive recipients of plastic pollution.”
Researchers also stress that plastic use in agriculture, including feed packaging, silage wrap and sludge fertilizer, contributes to microplastic contamination. Understanding how these particles behave in the digestive tract is becoming more urgent as plastics continue to accumulate on farmland.
The study was published in the Journal of Hazardous Materials. The authors report that the work was supported by remaining funds from previous animal nutrition projects at the Technical University of Munich.