Residues of zeta-cypermethrin in bovine tissues and milk following pour-on and spray application.
The depletion of zeta-cypermethrin residues in bovine tissues and milk was studied. Beef cattle were treated three times at 3-week intervals with 1 ml 10 kg-1 body weight of a 25 g litre-1 or 50 g litre-1 pour-on formulation (2.5 and 5.0 mg zeta-cypermethrin kg-1 body weight) or 100 mg kg-1 spray to simulate a likely worst-case treatment regime. Friesian and Jersey dairy cows were treated once with 2.5 mg zeta-cypermethrin kg-1 in a pour-on formulation. Muscle, liver and kidney residue concentrations were generally less than the limit of detection (LOD = 0.01 mg kg-1). Residues in renal-fat and back-fat samples from animals treated with 2.5 mg kg-1 all exceeded the limit of quantitation (LOQ = 0.05 mg kg-1), peaking at 10 days after treatment. Only two of five kidney fat samples were above the LOQ after 34 days, but none of the back-fat samples exceeded the LOQ at 28 days after treatment. Following spray treatments, fat residues were detectable in some animals but were below the LOQ at all sampling intervals. Zeta-cypermethrin was quantifiable (LOQ = 0.01 mg kg-1) in only one whole-milk sample from the Friesian cows (0.015 mg kg-1, 2 days after treatment). In whole milk from Jersey cows, the mean concentration of zeta-cypermethrin peaked 1 day after treatment, at 0.015 mg kg-1, and the highest individual sample concentration was 0.025 mg kg-1 at 3 days after treatment. Residues in milk were not quantifiable beginning 4 days after treatment. The mean concentrations of zeta-cypermethrin in milk fat from Friesian and Jersey cows peaked two days after treatment at 0.197 mg kg-1 and 0.377 mg kg-1, respectively, and the highest individual sample concentrations were 2 days after treatment at 0.47 mg kg-1 and 0.98 mg kg-1, respectively.
Rothwell
J T
JT
Elanco Animal Health, 16 Giffnock Ave, Macquarie Park, New South Wales 2113, Australia.
Burnett
T J
TJ
Hacket
K
K
Chevis
R
R
Lowe
L B
LB
D000273:Adipose Tissue / Q000378:metabolism; D000279:Administration, Cutaneous; D000818:Animals; D002417:Cattle; D005260:Female; D007306:Insecticides / Q000008:administration & dosage / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008892:Milk / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism; D010573:Pesticide Residues / Q000032:analysis*; D011722:Pyrethrins / Q000008:administration & dosage / Q000378:metabolism*; D014018:Tissue Distribution
D007306:Insecticides; D010573:Pesticide Residues; D011722:Pyrethrins; C017160:cypermethrin