A data-fitted mathematical sequence to calculate depuration rates for pesticide residues in milk from dairy cow feeding studies

A mathematical sequence is introduced to extract information on the rate of pesticide residue level increase and decline in milk from dairy cows dosed, for a number of days, with pesticide in a livestock feeding study. The sequence is governed by two parameters: 1) the added increment of residue concentration attributed to the daily dose and, 2) the constant proportion of residue dissipated in a day. Values for the parameters are obtained by finding the best fit of the sequence to the measured residues in the milk. Behaviour of the residue in the depuration phase (after dosing has ceased) is well predicted by the parameters obtained from the dosing phase. Not all dairy cow feeding studies have included a depuration phase, so the data-fitted mathematical sequence supplies the previously lacking information.