Assessment of estradiol and its metabolites in meat

Most studies related to research on steroids in main edible tissues (muscle , liver or kidney) have focused on measurement of parent or major metabolit e residues. In order to evaluate the estradiol content in bovine edible tis sues, a multi-step extraction procedure was developed in conjunction with p arallel metabolism studies of [C-14]-17 beta -estradiol in cattle (1-2). Va rious classes of free estradiol and conjugates were separated: estradiol -1 7 beta and -17 alpha, estradiol-17-fatty. acid esters, estradiol 17-glycosi de, estradiol 3-glucuronide, estradiol-17-glycoside and 3- glucuronide (dic onjugates) were separated. No sulphates conjugated forms have been found at the detection level of the method. The quantification was realized by cali bration with deuterated 17 beta -estradiol -d(3) standard and was validated at the ng . kg(-1) (ppt) level. Muscle, liver, kidney and fat samples from control or Revalor S (R) single (licensed implantation) or multi-implanted steers have been assayed. The results show a wide variation between animals, but both the highest val ue and the mean of total estradiol content in each group proportionally inc rease from untreated to multi-implanted animals. In accordance with interna tional rules, a calculation of the daily food supply of estradiol by such e dible tissues in comparison with the acceptable daily intake was performed.