Excretion of tetracycline and chlortetracycline in eggs after oral medication of laying hens.
After dosing laying hens orally with tetracycline (TC) through either drinking water (0.25 and 0.5 g/l for 5 days) or feed (300 and 600 ppm for 7 days), and chlortetracycline (CTC) through feed (600 ppm) residues were determined by an agar plate diffusion technique in cylinders with Bacillus cereus as test-organism, separately for albumen and for yolk. The sensitivity threshold was 0.07 micrograms/g in albumen and 0.15 micrograms/g in yolk for TC and 0.01 micrograms/g in albumen and 0.06 micrograms/g in yolk for CTC. Drug excretion via egg was 3-fold higher for TC than for CTC. The drug was excreted preferentially into the yolk (about 75% of the total amount) and the elimination period lasted between 6 and 11 days for TC and 9 days for CTC, after treatment. Tetracycline use in laying hens is discussed, taking into consideration the proposals presented by the joint FAO/WHO Expert Committee on Food Additives.
Roudaut
B
B
Ministère de l'Agriculture, Laboratoire National des Médicaments Vétérinaires, Fougères, France.
Moretain
J P
JP
Boisseau
J
J
D000821:Animal Feed; D000818:Animals; D002645:Chickens; D002751:Chlortetracycline / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D004530:Egg Yolk / Q000032:analysis; D004531:Eggs / Q000032:analysis*; D010047:Ovalbumin / Q000032:analysis; D013752:Tetracycline / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D014867:Water
D014867:Water; D010047:Ovalbumin; D013752:Tetracycline; D002751:Chlortetracycline