In vitro subcellular characterization of flunixin liver metabolism in heifers, steers, and cows.

The majority of cattle found to have violative liver residues of flunixin (FNX) in the United States are dairy cows. It has been hypothesized that illness of cows decreases the rate of FNX metabolism, resulting in violative residues at slaughter. Another contributing factor might be an age-related decrease in FNX metabolism, as dairy cull cows are typically older at slaughter than cattle raised for beef, rather than milk production.