Location: Food Animal Metabolism Research
2019 Annual Report
Accomplishments
1. Pork products free of chemical residues. Pork kidneys tend to concentrate veterinary drugs and other chemicals prior to their excretion and are therefore commonly used for monitoring violative drug residues. Research scientists at the Agricultural Research Service in Fargo, North Dakota, determined the occurrence of five commonly used animal health drugs in 1040 pork kidneys bought from retail markets. Using highly sensitive assay methods, none of the pork kidneys contained violative drug residues, and most of the kidneys contained no detectable drug residue. These data confirm that veterinary drug residues are usually absent in pork kidney available to consumers and fall well below regulatory thresholds when detected by highly sensitive analytical methods.
2. Contamination-level drug detection. Zilpaterol is a cattle feed additive banned by many U.S. trade partners, competitive sports organizations (animal and human), and livestock trade shows. Additionally, zilpaterol in food animals other than cattle is strictly proscribed. Research scientists at the Agricultural Research Service in Fargo, North Dakota, demonstrated that modern analytical methods are sufficiently sensitive, such that even trace-level zilpaterol exposures (commensurate with accidental exposures) can cause positive chemical residue tests in animal tissues. Sheep exposed to as little as one-thousandth of the normal zilpaterol dose could be positively identified using a variety of modern analytical tools. The data clearly confirm that animals exposed to the equivalent of trace-level zilpaterol contamination would likely test positive using a variety of common analytical methods.
3. Age-related drug metabolism in cattle. Flunixin is an effective anti-inflammatory agent commonly used in dairy cows that is approved by the U.S.-Food and Drug Administration. When used, cattle producers must wait 4 days from the last flunixin treatment to market animals for use as meat. However, flunixin residues exceeding the allowable level (set by the FDA) are one of the most common residue violations in dairy cattle. Dairy cattle are typically harvested at a much older age than beef cattle, because they can produce milk for up to 10 years. Agricultural Research Service scientists in Fargo, North Dakota, demonstrated that rates of flunixin metabolism in liver fractions of older (4 years or greater) cows were lower than in younger (2.5 years or less) steers and heifers. These findings support the theory that high flunixin residues in some dairy cows might, in part, be caused by age-related slowing of flunixin metabolism.
Review Publications
Chakrabarty, S., Shelver, W.L., Hakk, H., Smith, D.J. 2018. Atmospheric solid analysis probe and modified desorption electrospray ionization mass spectrometry for rapid screening and semi-quantification of zilpaterol in urine and tissues of sheep. Journal of Agricultural and Food Chemistry. 66(41):10871-10880. https://doi.org/10.1021/acs.jafc.8b03925.
Shappell, N.W., Duke, S.E., Bartholomay, K.A. 2019. In vitro subcellular characterization of flunixin liver metabolism in heifers, steers, and cows. Research in Veterinary Science. 123:118-123. https://doi.org/10.1016/j.rvsc.2018.12.012.
Shelver, W.L., Mcgarvey, A.M. 2019. Assessment of veterinary drugs present in pork kidney purchased from a Midwest US retail market. Food Additives & Contaminants: Part A. 36(4):571-581. https://doi.org/10.1080/19440049.2019.1586455.
Casey, F.X., Selbie, D., Hakk, H., Richards, K.G. 2019. Leaching of free and conjugate natural estrogens in soil monoliths. Water, Air, and Soil Pollution. 230:49. https://doi.org/10.1007/s11270-019-4079-z.
Smith, D.J., Shelver, W.L., Chakrabarty, S., Hoffman, T.W. 2019. Detection and quantification of residues in sheep exposed to trace levels of dietary zilpaterol HCl. Food Additives & Contaminants: Part A. 36(9):1289-1301. https://doi.org/10.1080/19440049.2019.1627005.
Shelver, W.L., Lupton, S.J., Shappell, N.W., Smith, D.J., Hakk, H. 2018. Distribution of chemical residues among fat, skim, curd, whey, and protein fractions in fortified, pasteurized milk. ACS Omega. 3(8):8697-8708. https://doi.org/10.1021/acsomega.8b00762.
