Isomerization of chlortetracycline in prairie wetland water.

Chlortetracycline (CTC), an antimicrobial administered as a feed additive to cattle, swine, and poultry, is present in the corresponding manure. Land application of raw or processed (composted or stockpiled) manure provides a mechanism by which CTC (and other antimicrobials) enters the environment and becomes available for transport to surface receiving waters via rainfall or snowmelt runoff. Chlortetracycline has been detected in Canadian surface waters, but little has been reported on its fate in aquatic ecosystems.

Persistence of the antimicrobials lincomycin, chlortetracycline, and sulfamethazine in prairie wetlands.

Antimicrobials used in livestock production can be present in manure via excretion in the feces and/or urine. Application of raw or processed (composted or stockpiled) manure to crop and pasture land as a plant nutrient source can result in antimicrobial transport to surface waters via rainfall or snowmelt runoff. Little is known regarding antimicrobial persistence in aquatic ecosystems.

Veterinary antimicrobials in feedlot manure: dissipation during composting and effects on composting processes.

Composting of manure may lead to the degradation of veterinary antimicrobials, but it is largely unknown if the presence of antimicrobials affects the composting process. Open-air windrow composting of manure from beef cattle (Bos taurus) administered chlortetracycline, sulfamethazine, and tylosin was investigated in a 2-yr study. At windrow construction, chlortetracycline had extensively isomerized to iso-chlortetracycline.

Transport of lincomycin to surface and ground water from manure-amended cropland.

Livestock manure containing antimicrobials becomes a possible source of these compounds to surface and ground waters when applied to cropland as a nutrient source. The potential for transport of the veterinary antimicrobial lincomycin to surface waters via surface runoff and to leach to ground water was assessed by monitoring manure-amended soil, simulated rainfall runoff, snowmelt runoff, and ground water over a 2-yr period in Saskatchewan, Canada, after fall application of liquid swine manure to cropland. Liquid chromatography tandem mass spectrometry was used to quantify lincomycin in all matrix extracts.

Fate of lincomycin in snowmelt runoff from manure-amended pasture.

Livestock manure containing antimicrobials becomes a possible source of these compounds to surface and ground waters when applied to agricultural land as a plant nutrient source. The potential for the transport of the veterinary antimicrobial, lincomycin, to surface waters via snowmelt runoff was assessed following field-scale fall injection of liquid swine manure into perennial grassland in Saskatchewan, Canada. This was achieved by monitoring snow melt runoff which accumulated in nineteen closed basin depressions, four ephemeral wetlands and two dugouts (small constructed reservoirs), approximately 6 months after manure injection.

Lincomycin and spectinomycin concentrations in liquid swine manure and their persistence during simulated manure storage.

Antimicrobials administered to livestock can be excreted up to 75% in the feces and urine. Liquid swine manure from confined animal feeding operations is generally retained in lagoon storage until it is applied as a nutrient source to crop and pasture land. Thus, the applied manure becomes a possible source of antimicrobials to aquatic ecosystems.

Development of a hydrophilic interaction chromatography-mass spectrometry assay for spectinomycin and lincomycin in liquid hog manure supernatant and run-off from cropland.

A specific and sensitive analytical method was developed to extract and quantify spectinomycin and lincomycin in liquid hog manure supernatant and simulated rainfall run-off from manure-treated cropland. Sample extracts were prepared using solid-phase extraction (SPE) employing a weak cation-exchange resin (Oasis WCX) for extraction of spectinomycin. An Oasis HLB cartridge was used for extraction of lincomycin.