Permethrin was tested for the protection of cattle against field populations of mosquitoes. Permethrin (500 ml of a permethrin 4.0 g liter-' aqueous emulsion) applied with a 'Dual-Cloud' electrostatic sprayer was effective in providing coverage of the cattle body surface of a group of four animals; 100 ml of a permethrin 5.0 g liter-' aqueous emulsion applied with a 'Dual-Cloud' electrostatic sprayer as a total body spray to a yearling heifer provided 70% or better protection from field populations of mosquitoes for at least 72 h; 500 ml of a permethrin 1.0 g liter-' aqueous emulsion applied as a low-pressure spray to the body of a yearling heifer provided 70% or better protection from mosquitoes for at least 140 h. Permethrin applied as a total body-spray thus provides adequate protection to cattle from field populations of mosquitoes.
Abstract:The pharmacokinetics of total radioactivity and of intact fenvalerate were determined in sheep treated intravenously with radiolabelled or nonradiolabelled fenvalerate. Mean residence times (MRT) of total radioactivity and intact fenvalerate in plasma were 910 (f 75) and 39 ( f 3) min, while harmonic mean elimination-phase half-lives (TM,) were 990 and 82 min, each respectively. Systemic clearance values (CI,) of total radioactivity and intact fenvalerate were 2.8 (k0.3) ml min-' kg-' and 51.3 (f5.9) ml min-' kg-', respectively. Volumes of distribution at steady state (V,) were each near 2500 ml kg-'. Elimination of radioactivity occurred, in part (33.3 (f 3.3)% of dose), by renal excretion, at a rate (0.9 (kO.1) ml min-' kg-I), similar to that of glomerular filtration. These data are consistent with a disposition model according to which intact fenvalerate was rapidly distributed into a peripheral compartment, where metabolism occurred. In addition, since the elimination half-life of fenvalerate from plasma was less than 90 min after intravenous injection, 'flip-flop' kinetics should be considered when longer elimination half-lives are observed after oral or dermal exposures.
Danielson, T. J. and Golsteyn, L. R. 1997. Weight gain and feed utilization in Hereford steers exposed to diazinon. Can. J. Anim. Sci. 77: 181-183. Body weights and feed consumption were monitored in 48 Hereford steers, under feedlot conditions, for 10 wk after exposure to diazinon, an organophosphate insecticide. Experimental design consisted of four complete blocks, each of four treatment groups (positive and negative controls, two insecticidal ear tags and four insecticidal ear tags). Plasma cholinesterase activity was reduced by 50%, 24 h after topical application of diazinon directly to the skin (positive control) but was not reduced after attachment of either two or four insecticidal ear tags per animal. Daily weight gain and feed utilization in control animals, during the 70-d study, were 1.21 ± 0.22 kg d -1 and 0.144 ± 0.007 kg kg -1 (dry matter basis) and were not altered in steers exposed to diazinon.
: Experiments were conducted to identify pharmacokinetic interactions between topically applied piperonyl butoxide and intravenous fenvalerate in cattle (Angus steers). Intact fenvalerate in plasma was derivatized by condensation with acetone and measured by negative chemical ionization gas chromatography/mass spectrometry. Noncompartmental pharmacokinetic analyses indicated that the elimination-phase rate constant (b, 0É000 69 (^0É000 06) min~1), mean residence time (172 (^14) min), systemic clearance (10É4 (^0É7) ml min~1 kg~1) or volume at steady state (1800 (^230) ml kg~1) were not changed (P [ 0É05) after topical application of a low dose of piperonyl butoxide. These data indicate that topical application of a low dose of the metabolic synergist piperonyl butoxide would not be expected to modify the in-vivo disposition of fenvalerate in cattle.
The pharmacokinetics of total radioactivity and of intact fenvalerate were determined in sheep treated intravenously with radiolabelled or nonradiolabelled fenvalerate. Mean residence times (MRT) of total radioactivity and intact fenvalerate in plasma were 910 (f 75) and 39 ( f 3) min, while harmonic mean elimination-phase half-lives (TM,) were 990 and 82 min, each respectively. Systemic clearance values (CI,) of total radioactivity and intact fenvalerate were 2.8 (k0.3) ml min-' kg-' and 51.3 (f5.9) ml min-' kg-', respectively. Volumes of distribution at steady state (V,) were each near 2500 ml kg-'. Elimination of radioactivity occurred, in part (33.3 (f 3.3)% of dose), by renal excretion, at a rate (0.9 (kO.1) ml min-' kg-I), similar to that of glomerular filtration. These data are consistent with a disposition model according to which intact fenvalerate was rapidly distributed into a peripheral compartment, where metabolism occurred. In addition, since the elimination half-life of fenvalerate from plasma was less than 90 min after intravenous injection, 'flip-flop' kinetics should be considered when longer elimination half-lives are observed after oral or dermal exposures.
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