Effects of antibiotics consumption on the behavior of airborne antibiotic resistance genes in chicken farms

The antibiotics and antibiotic resistance genes (ARGs) have caused pollution of livestock farm environments. There are limited investigations about airborne ARGs and what role the antibiotics play remains largely unclear. The dynamics of various antibiotics were compared between feces samples from chicken fed a diet with and without antibiotics. In contrast to the farm with no antibiotics drugs, the hazard quotients (HQs) of OTC (24.8-205.4) and CTC (18.0-317.0) are particularly high in the farm with in-feed antibiotics drugs. The high ecological risks of antibiotics in chicken feces with in-feed antibiotic drugs were 100 % as determined. We quantified mobile genetic elements (MGEs) and ARGs and investigated bacterial communities in feces and air samples. The concentration of airborne ARG/MGE subtypes with in-feed antibiotic drugs is about two orders of magnitude higher than those without drugs. This study reveals that the indoor air of chicken farms is a reservoir of ARGs in the environment. Continuous feeding of antibiotics can change the intestinal microbial community structure of the chicken. The possibility of horizontal gene transfer of ARGs in air and feces samples might be increased by in-feed antibiotic drugs. The enrichment of ARGs in the chicken farm can be reduced by minimizing antibiotic use.