Figure 2.

Schema of the 3-compartment model of QA toxicokinetics in dairy cows. The central compartment represents the entry point for QAs into the cow and the output site for elimination (grouping unabsorbed as well as putatively metabolized and/or excreted QAs). The peripheral compartment acts as a small storage. The udder compartment is where the milk is produced, stored, and periodically emptied at milking events (together with the QAs contained). The parameter k_ij represents the transition rate from compartment i to compartment j for the compartments: i,j = C, Central; P, Peripheral; U, Udder; and E, Elimination.