MP9 Developing Reliable Endpoints in Avian Endocrine Testing at the Population Level
Room 12A/B, Level 4
2:10 PM - 5:30 PM, Monday, 10 November 2003
Chair: Brugger, Kristin ,
(160) Comparing Species Sensitivity to Dietary Methoxychlor in a Two Generation Test.
Ottinger, M1, Hazelton, J1, Quinn, M1, Thompson, N 1, Wu, J1, Quigley, E1, Abdelnabi, M1, Beavers, J2, Fry, L2, Jaber, M2, 1 Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA2 Wildlife International,Ltd., Easton, MD, USA
ABSTRACT- Because of a vast array of reproductive strategies, it has been difficult to ascertain reliable end points that are representative for a variety of birds. The two-generation dietary test provides a platform for determining the effects of exposure to an endocrine disrupting chemical (EDC) at various stages of the life cycle. In this way, consequences of EDCs can be ascertained relative to timing and duration of exposure of individuals. Two-generation studies were run concurrently with Japanese and northern bobwhite quail with dietary methoxychlor (MXC) exposure (0, 5ppm, and 10ppm). The parent generation (P1) was raised under short photoperiod and paired, placed on a 16L: 8D photoperiod, with initiation of treatment at photostimulation. Feed intake, egg production, fertility, offspring viability were monitored; chicks (F1) were raised on the same diet as their parents, paired as adults, and monitored for sexual maturation, reproductive behavior and endocrine measures. F2 chicks were raised on control feed and assessed for the same end points as the F1 birds. Results showed that bobwhite quail matured more slowly and had lower productivity. Although dietary MXC did not affect general measures of health and reproduction, both species showed delayed sexual maturation with treatment, with reduced reproductive performance at 10ppm MXC. Sexual behavior was impaired by MXC exposure in F1 and F2 Japanese quail males; behavioral assessment was not conducted in bobwhite males. Plasma steroid hormones reflected reproductive performance. Overall, Japanese and bobwhite quail showed similar response to dietary MXC, in spite of differences in the timing of maturation. These data support the use of a model species for evaluating EDC impact in birds, with the proviso that absolute magnitude of effect will differ and precocial species are likely to be more sensitive to embryonic exposure. Supported by EPA R-82877801
Key words: methoxychlor, Japanese quail, reproductive endocrine end points, endocrine disruption