Animal Industry Report

Extension Number

ASL R2536



Summary and Implications

The triazine herbicide, atrazine, has come under scrutiny for its reported feminizing effects in amphibians. To date, there is little information concerning the effects of atrazine on reproduction in avian species. The current study examines the putative reproductive toxicity of atrazine after exposure in ovo. Atrazine at 504, 246 and 123 µg/kg was administered to Japanese quail eggs prior to incubation. The eggs were hatched and the birds raised to 14-days of age. Indices of hatchability, sex ratios and growth were determined. Furthermore, circulating concentrations of reproductive hormones (estradiol, progesterone and testosterone) and gonadal histology were examined. Atrazine at 504 µg/kg decreased 14-day hatchling weight 13.1% versus control. However, no detrimental effects on hatchability or sex ratios were observed. In female birds, atrazine at 504 µg/kg reduced ovarian weights and circulating concentrations of progesterone 48.3 and 73.3%, respectively, versus control. However, concentrations of estradiol and testosterone did not differ from control. In male quail, at all doses tested, atrazine reduced circulating concentrations of testosterone as much as 80.2% versus control. However, no effects on gonadal weights or circulating concentrations of estradiol or progesterone were observed. Moreover, no incidences of left ovotestis formation were observed. In contrast, 10 ng/kg ethinylestradiol (a positive control) induced the formation of a left ovotestis in 4 of 8 birds analyzed. The current results may suggest that exposure to atrazine in ovo at concentrations above ecological relevance exerts modest effects on the reproductive system of the young male and female quail. However, no evidence is presented that atrazine induces feminization of the testis in the male quail.

Copyright Holder

Iowa State University