Estradiol-17beta and linseed meal interact to alter visceral organ mass and hormone concentrations from ovariectomized ewes.

To evaluate the estrogenic potential of secoisolariciresinol diglycoside (SDG) found in linseed meal (LSM) on visceral organ mass, IGF-I, and thyroid hormone (T(3) and T(4)) concentrations, 48 multiparous, ovariectomized ewes (54.6 +/- 1.1 kg) were used in a 3 x 4 factorial arrangement. Main effects were length of LSM feeding (0, 1, 7, or 14 d) and length of exposure to estradiol-17beta (E(2)) implant (0, 6, or 24 h prior to tissue collection). Implanting ewes with E(2) for 24h increased liver mass relative to empty body weight (EBW; g/kg EBW) compared with ewes implanted for 0 or 6 h (P <or= 0.03), whereas feeding LSM for 14 d decreased liver mass compared with ewes fed LSM for 1 or 7 d (P <or= 0.02). There was an LSM x E(2) interaction (P = 0.01) for duodenal mass (g/kg EBW), LSM, and E(2) tended (P = 0.07) to influence the stomach complex mass; however, ileal mass was not affected. Neither LSM nor E(2) affected (P >or= 0.12) CYP2C or CYP3A mRNA expression or cellularity of the liver. Exogenous E(2) influenced circulating concentrations of IGF-I, T(3), and T(4). The estrogenic or anti-estrogenic potential of LSM is dependent upon the tissue, exposure to E(2), and the duration of LSM feeding. Feeding LSM during gestation, lactation, or during the grow-finish phase warrants further investigation.