Aeration Effect On Antibiotic Dissipation in Swine Slurry.

Veterinary antibiotics have been used to promote growth of livestock and increase feed efficiency in addition to treat disease. The antibiotics administered into livestock are generally excreted via feces and urine. Before animal manure or slurry is applied into agricultural land, the antibiotics need to be reduced or removed during composting or other managements. The objective of the study was to examine the effect of aeration on antibiotic dissipation in swine slurry. The swine slurry used in the study contained two antibiotics; tetracycline (TC) and tylosin (TYL). One hour aeration per day decreased TC concentration in the swine slurry from 199 to 43 ng/L, about one fifth of the initial concentration, 62 days after treatment, while 104 ng/L without aeration. Three and six hours aeration per day decreased TC level to 30 and 23 ng/L, respectively. The dissipation of TC was fitted with a simple first-order kinetic model. The first-order rate constant, k, was increased from 0.011 to 0.022, 0.026, and 0.037 by aeration for 1, 3, and 6 hours every day, respectively. A greater k value means faster degradation. For TYL, aeration also increased k from 0.0074 under anaerobic condition to 0.014, 0.018, and 0.031 for 1, 3, and 6 hours per day, respectively. This results suggest that aeration may enhance the degradation of antibiotics during storage of swine slurry.