Plasma estradiol-17ß concentrations in the cow during induced estrus and after injection of estradiol-17ß benzoate and estradiol-17ß cypionate -a preliminary study |
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| Authors: | L VYNCKIER M DEBACKERE A De KRUIF M CORYN |
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| Institution: | Laboratory of Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, R.U.G., Gent, Belgium. |
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| Abstract: | 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. |
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