Effect of genistein on the growth and reproductive function of male and female yellow perch Perca flavescens

We studied the effect of genistein, a weak estrogenic compound found in soy bean products, on the growth and reproductive development of yellow perch P er cn flavescens. Four diets were prepared: control, estradiol-17 beta (E-2 ) at 10 mu g/g diet (E10), and genistein at 7.5 and 0.75 mg/g diet (G7.5 an d G0.75). Fish (initial weight = 13-15.5 g and initial total length = 105-1 11 mm) were fed to excess for 63 d. The E10 diet promoted weight gain in ye llow perch of both sexes, whereas the G7.5 diet decreased weight gain in fe males. The growth of the G0.75 group was not different from either the E10 group or the control group. Among females, fish fed the E10 diet had the lo west plasma concentration of E-2 36 h after the last feeding of the study. The plasma concentration of E-2 did not differ among the males from the fou r treatments. The E10-treated fish of both sexes had increased plasma conce ntration of alkali-labile phosphoprotein phosphorous (ALPP) in both sexes, indicating that vitellogenesis had been induced. Neither genistein diet inc reased plasma (ALPP) concentration. Male but not female yellow perch fed th e E10 diet had significantly lower gonadosomatic indices compared to contro l and genistein groups. These results suggest that genistein may have a pos itive effect on growth in yellow perch, but no apparent estrogenic effects on reproductive function.