National Science Centre, OPUS 21 “Threats related to antibiotic contamination of feed” 2022-03-01 – 2026-02-28

Project Manager: Ewelina Iwan, PhD

Funding: PLN 527,703.00

Project Description: The use of antibiotics in food-producing animals is one of the primary concerns for consumers. Understandably so, as antimicrobial resistance is a global public health threat. Although the use of antimicrobials in veterinary medicine is decreasing in Europe, this trend is not always evident in Poland. Even more concerning, the use of certain antibiotics critical to human medicine (such as polymyxins and fluoroquinolones) is among the highest in Europe. Antimicrobials are administered to animals through various routes. In pigs and poultry, administration via drinking water and medicated feed is preferred due to its practicality. However, producing high-quality medicated feed is challenging; furthermore, subsequent batches of feed produced by the same feed company can be subject to cross-contamination. The European Commission has recognized this issue and intends to introduce legal limits for antibiotic cross-contamination in feed. However, reliable data on the potential impact of low doses of antibiotics administered to animals over extended periods are needed for this purpose. Our project aims to address this need. We intend to verify the possible impact of low doses of antibiotics on animal and human health, as well as the environment. The approach is broad and includes the emergence of antimicrobial resistance and subtle effects on animal physiology, including the microbiome’s metabolism of bioactive compounds and immunology. The animal experiment will be conducted on broilers. Six different antibiotics (doxycycline, flumequine, colistin, thiamphenicol, tiamulin, tylmicosin) will be tested and compared with a control group. Antibiotics will be administered in feed throughout the rearing period at doses equivalent to 2% of the maximum approved concentration. The following parameters will be analyzed: • Monitoring of clinical status and production results; • Histopathological analyses of the intestines and spleen; • Changes in the gut microbiome (percentage of specific bacterial genera/species and occurrence of antimicrobial resistance genes); • Metabolic activity of the gut microbiome, which may affect animal physiology; • Transcriptomic profile of the cecum, spleen, liver, and pancreas, indicating, among other things, the animal’s immune status; • Interactions with CYP450 enzymes in the liver and intestines, which may affect the action of other drugs administered to animals; • Antibiotic residues in muscles, liver, and kidneys; • Meat quality. The European Food Safety Authority is to conduct a risk analysis related to antibiotic cross-contamination in feed. This project will provide data for such an analysis. Furthermore, the project results can be used by producers wishing to raise animals without the use of antibiotics.