The effects of biotic treatments on degradation of antimicrobials and coccidiostats in broiler litter used as ruminant feed

Abstract

While broiler litter (BL) represents a valuable protein source for ruminant feed, the presence of pharmaceutical residues poses significant concerns for food safety and antimicrobial resistance. Previous research has primarily focused on composting and aerobic digestion of BL, leaving a critical knowledge gap regarding the comparative efficacy of economically viable treatment methods. This study presents the first systematic comparison of three cost-effective treatments—stacking, aerobic, and anaerobic processing—specifically analyzing their impacts on pharmaceutical compound degradation in BL intended for ruminant feed. Using LC/MS/MS analysis, we evaluated the degradation patterns of 29 antimicrobials and coccidiostats under controlled conditions, while simultaneously monitoring key parameters including temperature kinetics, pH fluctuations, short-chain volatile fatty acids (SCVFA), and nutritional content. Our findings revealed that stacking treatment demonstrated superior degradation efficiency for most compounds, achieving > 95% degradation for key antimicrobials and 54.9–74.7% for commonly used coccidiostats. Notably, the stacking method maintained optimal crude protein levels (32–34.8%) while reducing moisture content by 29.5–34.6%. Temperature profiles showed distinct patterns: aerobic treatment reached 60 °C within 24 h, while stacking achieved 50 °C over 2 weeks, both significantly outperforming anaerobic treatment (38 °C). This research provides the first comparative evidence for selecting cost-effective BL treatment methods, offering practical guidelines for agricultural operations to minimize pharmaceutical residues while preserving nutritional value for ruminant feed.