USDA-Agricultural Research Service (ARS) scientists are studying how oxytetracycline (OTC), an antibiotic that is administered to animals, breaks down in cattle manure.  

The researchers found that in controlled laboratory conditions, OTC in cattle manure was degraded more quickly as temperatures increased and as the moisture content in the manure increased. But the OTC breakdown slowed as water saturation levels neared 100 percent. Scientists conclude that this slowdown resulted when oxygen levels were not high enough to fuel the OTC biodegradation.

They also note that OTC breaks down more quickly in manure than in soil. Compared to soil, manure has higher levels of organic material and moisture that support the microorganisms that break down this pharmaceutical.

This laboratory research may be useful in designing studies that evaluate the potential effects of lagoons, holding ponds and manure pits on bacteria and antimicrobial resistance.

The study was published in theJournal of Agricultural and Food Chemistry.