Toxicity of high dietary levels of DDT in laying hens.

White Leghorn hens were fed diets containing 0, 300, 600, or 1200 ppm technical grade DDT for three 28-day periods. The 1200 ppm diet caused tremors and 33% mortality in the final period, but no gross toxicity symptoms were seen in birds fed the other diets. Egg production was decreased during the third period by 600 or 1200 ppm. Egg weight was decreased during the third period by 600 or 1200 ppm. Egg weight was decreased during the last two periods by 1200 ppm. Shell thickness was decreased in all three periods by feeding 600 or 1200 ppm DDT. Dietary DDT caused no change that could be detected by shell beta backscatter. Shell weight as a percent of total egg weight was decreased by 600 or 1200 ppm DDT.