Antibiotic residues in cattle manure increase greenhouse gas emissions during solid storage in Kenya

Abstract

The increasing use of antibiotics in livestock farming raises concerns about environmental impacts. This study examined the effects of three commonly used veterinary antibiotics – Tylosin, Enrofloxacin, and Oxytetracycline – on manure greenhouse gas (GHG) emissions and fertilizer quality during solid manure storage. Aliquots of fresh cattle manure (10 kg) were either spiked with high or low concentrations of each antibiotic, or left untreated as Control, then incubated in open buckets for 110 days to simulate manure heaping. Emissions of CO2, CH4, and N2O were measured using a static chamber with a laser spectrometer. Tylosin (High and Low) treatments and High-dose Enrofloxacin significantly increased manure N2O emissions (2.1 ± 0.2 to 2.5 ± 0.4 %), exceeding the IPCC default values of 1 % manure-N. All antibiotic treatments increased CH4 emission factors (6.4 ± 0.7 to 14.2 ± 1.1 g CH4 kg