On‐farm screw press and rotary drum treatment of dairy manure‐associated antibiotic residues and resistance

Abstract

Core Ideas  Only sulfadimethoxine and oxytetracycline residues were detected in manure samples.  Most antibiotic resistance genes (ARGs) partitioned with separated manure liquids.  tetO was primarily associated with separated manure solids (SS).  A rotary drum composter (RD) treated SS from antibiotic-treated cattle.  The RD significantly reduced all four ARGs and oxytetracycline residues.

Antimicrobial resistance in dairy slurry tanks: a critical point for measurement and control

“…Specifically, secondary storage of slurry for a period of 60 days, without fresh inflow, would significantly reduce the levels of ARB within the tank, representing an opportunity for rational farm design and practice to minimize AMR outcomes. This result is also concordant with other practices for mitigating AMR on farms, including the use of anaerobic digestion (79,88), vermicomposting and solid-liquid separation (43).…”

“…Meanwhile, studies assessing how cattle faecal resistomes respond to contrasting antibiotic management practices generally place emphasis on individual cattle (40)(41)(42), with different microbiomes, rather than the collective faecal output of the herd. Liquid-solid separation of manure may also influence the persistence of AMR (43).Therefore, there is a need for detailed longitudinal studies of AMR in dairy slurry and potential mitigations.…”

Quantifying Antibiotic Distribution in Solid and Liquid Fractions of Manure Using a Two-Step, Multi-Residue Antibiotic Extraction

“…A blank dairy manure (BDM) sample was collected at the Beltsville Agricultural Research Center (Beltsville, MD USA) farm from dairy cows that were free of antibiotics and included in the extraction experiments. Dairy manure substrates from a farm located in New York, US that used solid/liquid separation, with the liquid manure sent to a lagoon and the separated solids subsequently heat treated using a bedding recovery unit (BRU), were collected and used to compare extraction efficiencies from different manure types [ 38 ]. Manure was collected at four points in the bedding recovery treatment process: (1) unprocessed pit manure (UPM), (2) separated liquid manure (SL), (3) separated solids (SS) from the top of a screw press, and (4) solids heat treated using the bedding recovery unit (BRU).…”

Antimicrobial Resistance in Dairy Slurry Tanks: A Critical Point for Measurement and Control

“…Meanwhile, studies assessing how cattle faecal resistomes respond to contrasting antibiotic management practices generally place emphasis on individual cattle (Halbert et al, 2006;Feng et al, 2019;Feng et al, 2020), with different microbiomes, rather than the collective faecal output of the herd. Liquid-solid separation of manure may also influence the persistence of AMR (Oliver et al, 2020). Therefore, there is a need for detailed longitudinal studies of AMR in dairy slurry and potential mitigations.…”