Effects of Dietary Methyl Parathion on Northern Bobwhite Egg Production and Eggshell Quality

Abstract

There is a need to develop avian reproduction tests that reflect more realistic exposure scenarios for short‐lived pesticides, like organophosphorus and carbamate compounds. The effect of a short‐term dietary methyl parathion exposure on northern bobwhite (Colinus virginianus) egg production and shell quality was investigated. Hens in egg production were fed either a methyl parathion diet (0, 14, 20, 28 or 40 ppm) or a pair‐fed diet (PF28 and PF40 received the same daily allotment of control feed on a g/kg/d basis as the 28 or 40 ppm‐treated hen with whom she was paired) for 8 d. Daily food consumption was significantly reduced in all treatment groups and inversely related to chemical concentration. However, actual chemical consumption was similar for all methyl parathion‐treated groups. Body weight, egg production, egg weight and eggshell strength, thickness and weight were reduced in the methyl parathion groups in a dose‐related manner. Similar responses were observed in the pair‐fed groups, indicating that effects were associated with a pesticide‐induced reduction in food consumption. The dietary methyl parathion exposure impacted bobwhite egg production within 3 to 4 d and eggshell quality within 1 d of the onset of treatment.