Effects of dietary methyl parathion on northern bobwhite egg production and eggshell quality

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.