Adult chickens were dosed with 10 mg of , '-DDT per kg of body weight daily for 90 days and then killed. The residues of , '-DDT and related compounds were higher in the tissues of treated adult males than in tissues of treated hens. The highest residue levels were found in the fats and preen gland, and the lowest levels were in the breast muscle and brain. The residue levels in control chickens were unchanged throughout the study.Yolks of eggs collected prior to the start of the study and at 30-day intervals during the study were analyzed for residues. Peak residues were found at 60 and 90 days. The tissues of chicks hatched from eggs collected during the 13th week of the study were analyzed. Peak residue levels were found at either day 1 or 7 after hatch. Residues had practically disappeared by 21 days after hatch. No residues were found in chicks of control chickens.A tremendous amount of research has been published since the discovery of l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and two of its metabolites, l,l-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 1,1dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE). A review article by St. Omer (1970) gives a background on the research of chlorinated hydrocarbon insecticides.In the area of residues, work has been done in all types of domestic animals, fish, and wildlife, including quail, falcons, eagles, and ducks. These residue studies have been linked directly with metabolism studies. An article by French and Jefferies (1969) gave the metabolism of , '-DDT in both living and dead avian tissues. The o,p'-DDT is broken down to , '-DDT and then to DDE in living avian tissues. In dead avian tissues, the , '-DDT is metabolized to DDD.Residues of DDT and metabolites have been determined in eggs and chicken tissues (Ecobichon and Saschenbrecker, 1968;Graves et al., 1969;Herrick et al., 1969) after shortterm feeding trials. In other studies, the residues were traced after injections of DDT and metabolites into the avian embryo (Abou-Donia and Menzel, 1968; Guthrie and Donaldson, 1970). Other researchers have attempted to deplete the DDT residues in laying hens (Wesley et al., 1969) and cockerels (Ecobichon and Saschenbrecker, 1969) by various means.
