Plasma estradiol-17 beta concentrations in the cow during induced estrus and after injection of estradiol-17 beta benzoate and estradiol-17 beta cypionate--a preliminary study.
Plasma estradiol-17 beta concentrations were investigated in cows during induced estrus and after an intramuscular injection of 10 mg of estradiol-17 beta benzoate and estradiol-17 beta cypionate to determine a withdrawal period for both preparations. After the estradiol-17 beta benzoate injection, the plasma estradiol-17 beta concentration was higher than the physiological maximum of 24 pg/ml obtained during induced estrus for a period of 114 +/- 10 h (mean +/- SEM). For estradiol-17 beta cypionate the corresponding value was 170 +/- 17 h (mean +/- SEM). A withdrawal period of 7 days for the benzoate ester and of 10 days for estradiol-17 beta cypionate is therefore proposed. These results were confirmed by biopsies taken at the injection site 8 and 15 days after the injection of estradiol-17 beta benzoate and estradiol-17 beta cypionate, respectively. In these biopsies no residues of estradiol-17 beta nor of its esters could be detected.
Vynckier
L
L
Laboratory of Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, R.U.G., Gent, Belgium.
Debackere
M
M
De Kruif
A
A
Coryn
M
M
D000818:Animals; D002417:Cattle / Q000097:blood*; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood* / Q000378:metabolism; D004971:Estrus / Q000097:blood*; D005260:Female; D007273:Injections, Intramuscular / Q000662:veterinary; D013997:Time Factors
D004958:Estradiol; C007630:estradiol 17 beta-cypionate; C010452:estradiol-17 beta-benzoate