Excretion of deltamethrin in lactating dairy cows.

A study was conducted to determine the metabolic fate of deltamethrin in lactating cows after a 'pour-on' application. Two cows were treated with 0.1 g deltamethrin and two with 1 g of the compound. Urine, faeces, milk and blood were collected over an 8-day period and analyzed for deltamethrin. This preliminary experiment has shown that it is necessary to undertake further experiment of longer duration (1 month). Deltamethrin was rapidly absorbed and slowly excreted. In milk, residues levels were very low: less than 1% of the treatment dose, and maximum levels were reached after 2 days (0.009 micrograms/ml for 0.1 g deltamethrin and 0.053 micrograms/ml for 1 g deltamethrin). For cows 1 and 2 (0.1 g deltamethrin), no residue level was detected at the detection limit (0.001 micrograms/ml) after 8 days. A total of 0.3-0.6% of excreted deltamethrin was present in urine, and no residue was found after 8 days. The major route for elimination was via faeces (about 95% of the total eliminated compound). Maxima were reached after 2 days and were still present after 8 days. Results shown in this study substantiate previously published work.