Relation between DDT in Diets of Laying Birds and Viability of their Eggs

Abstract

CONCERN at the presence of organo-chlorine insecticides in birds' eggs has stimulated attempts to relate concentrations of toxicants in eggs to hatchability¹. We have tried to relate the ingestion of DDT by adult birds to the viability of their eggs. Initially we carried out a pilot study similar to that of Cross et al.² and followed this with the study described here, in which diets containing 200 p.p.m. of DDT were fed after the start of laying to caged Japanese quail (Coturnix c. japonica). Eggs were set at weekly intervals before and after the start of feeding of DDT and the hatchability of the eggs and survival of chicks were compared with those of a control group. The concentration of DDT in the treated diet is expressed as the amount of the (pp) isomer contained in a commercial wettable powder containing 35 per cent (pp) and 10 per cent (op) isomers. On this basis, the mean weight of pp DDT consumed per bird per week was estimated at 28 mg for the first week and 22 mg for the second.