ARS | Publication request: Distribution of veterinary drug residues among muscles

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2010
Publication Date: June 1, 2010
Citation: Schneider, M.J., Solomon, M.B. 2010. Distribution of veterinary drug residues among muscles. Meeting Abstract. 31.

Technical Abstract: The U.S. Food and Drug Administration sets tolerances for veterinary drug residues in muscle, but does not specify which muscle should be sampled for analysis. The goal of this research was to determine if antibiotic residue levels are dependent on muscle type. In this study, penicillin G (Pen G) distribution in muscle of culled dairy cows was examined. Cows were dosed for 3 days, and then sacrificed on days 1, 2 or 5 of withdrawal. A selection of incurred muscle samples, divided into two portions, were collected, along with liver and kidney samples. Corresponding muscle juice samples were also prepared. All samples were extracted and analyzed by LC-MS/MS to determine Pen G levels. Muscle levels of Pen G were lower than those of liver or kidney, except for injection site muscles, which were elevated. Pen G levels decreased significantly in muscle between Day 1 and Day 2 of withdrawal. Distribution of Pen G in both muscle and muscle juice samples for Day 1 of withdrawal are described. Differences in Pen G levels were observed between muscle types, and in some cases, within muscles, suggesting that sampling may be a complex issue and that a standardized sampling approach could be helpful.