In 1954 Snair, et al. (30) stated that residues containing significant amounts of 
stilbestrol had been recovered from the fatty tissue of poultry after the pellet implanta- 
tion of stilbestrol. Stob, et al. (31) reported measurable estrogenic activity which did not 
exceed 0.1 Ug./gm. dried tissue after treatment of chickens with 12 mg. stilbestrol 
pellets for 1, 2, 3, or 4 weeks. They point out that this is a rather high level of hormone 
in comparison with sheep and cattle when considered on a dose per unit of body weight. 
In this assay for estrogens the dried tissues were directly incorporated into the diet of 
the test mice instead of preparing extracts of the hormone containing tissues. 
Merker, et al. (24) did not detect any estrogenic activity in either the free or 
conjugated residues of extracts obtained from chickens which had been treated with 12 
mg. stilbestrol pellets. 
Umberger, et al. (39) also studied the estrogenic residues in the edible tissues of 
stilbestrol implanted chickens using a sensitive bioassay in which immature mice were 
fed the chicken tissues directly. Stilbestrol was applied to the chickens in either 12 mg. 
pellets, a 15 mg. paste, a 15 mg. liquid rosin, or 15 mg. liquid preparations. Measurable 
estrogenic residues were detected after the use of either of the first three methods of 
administration. No activity was detected 5 weeks after the use of the liquid preparation. 
The amounts of estrogenic activity were equivalent to 20 to 30 p.p.b. of stilbestrol in 
the liver and to 35 or more p.p.b. in the fat of the skin, Detectable amounts also occur 
in the kidneys and smallintestines ofthe treated birds. Smaller amounts, 0.5 to 1.8 p.p.b., 
were found in the breast and leg muscles. Ina review of the literature on estrogenic 
residues in poultry Umberger, et al. (39) pointed out that in only a few cases were the 
treated tissues fed to the assay animals; the other assays involved extraction of the 
estrogen from the tissues with attendant possibilities of losses. 
The residual estrogens found in meat appear to be relatively stable to heat, Thus, 
Stob, et al. (31) found no losses after cooking. Taylor and Gordon (35) also found no 
destruction of estrogenic activity in swine tissues by cooking. Umberger, et al. (39) 
also found no losses in diethylstilbestrol content in chicken tissues due to cooking. 
Stability of hexestrol in excreta appears to be high. A recent report (44) has shown 
estrogenic activity in silage contaminated with manure from estrogenized steers which 
persisted for several months, 
REFERENCES 
1, Andrews, F.N., Stob, M., Perry,T.W.,and Beeson, W.M. J. An. Sci. 15: 575 (1956). 
2. Beeson, W. M., Andrews, F.N., Perry, T. W. and Stob, M. J. An. Sci. 14: 475 (1955), 
3. Bird, S., Pugsley, L.I.,and Klotz, M.O. Endocrinology 41: 282 (1947). 
4 
. Campbell, E. D., and Wick, H. Endocrine Laboratories Report pp. 1438-1439. (See 
Meyer, R. K. for ref.) 
5. Colombel, J. Rec. de Med. Veterinaire Paris 126: 100 (1950). 
6. Cowie, A. T., and Flux, D.S. J. Endocrinol. 11: 255 (1954). 
7. Ellis, N. R., Davis, R. E., and Denton, C, A. Antibiotics, Hormones, Tranquilizers 
in Animal Production Symposium USDA April 27-29, 1960. 
8. Ellis, P. J., Allen, ©. E., and Whiting, F. Canad. J. Agroisci. 347292 (954): 
9. Davey, R. J., Armstrong, D. T., and Hansel, W. J. An. Sci. 18: 75 (1959). 
10. Dodgson, K. S:, "Garton, ©. A., Stubbs, A. i.,,and Williams, RK. 1.) Biochem.) 0. 
42; 357 (1948). 
11. Glascock, R. F., and Hoekstra, W.G. Biochem. J. 72: 673 (1959). 
12. Gossett, F. O., Smith -- and Downing -- Symposium on Medicated Feeds 1956, 
Washington, D.C. 
216 
