Dietary Calcium, DDT Source and Age of Hen on the Reproductive Performance of Caged White Leghorns Fed DDT

Abstract In Experiment 1 eight groups of 20 caged White Leghorn pullets each were fed 0, 10 or 50 p.p.m. technical grade DDT from two different manufacturers (#1 or #2), 10 or 50 p.p.m. combination of pure DDT isomers, or 50 p.p.m. p,p′-DDT in a 3.5% calcium breeder diet, and eight counterpart groups were fed the same pesticides in a 1.5% calcium diet for 40 weeks. The traits studied were body weight gains, egg production, livability, feed intake, fertility and hatchability. Significant effects included calcium level for body weight gains, egg production, livability and feed intake, in favor of 3.5% calcium, irrespective of DDT, and calcium × diet for body weight changes, in which some of the pesticide-supplemented groups were significantly different from one another but none were superior to the control group on each calcium level. In Experiment 2 four groups of 20 pullets each were fed 0, 10 or 50 p.p.m. technical grade DDT #1 or 50 p.p.m. p,p′-DDT in a diet containing 3.5% calcium for 20 weeks, 3.0% the next 12 weeks and 1.0% the final 8 weeks. The data showed no basic differences due to DDT among pullets fed periodic decreases of calcium, as compared with the controls. Experiment 3 consisted of six groups of yearling hens fed 0, 10 or 50 p.p.m. technical grade DDT #1 or #2 or 50 p.p.m. p,p′-DDT in a 3.5% calcium diet. The 28-week data indicated that yearling hens significantly gained less and laid fewer eggs than their counterpart pullet groups fed 3.5% calcium in Experiment 1, irrespective of DDT. DDT effects were nonsignificant between hens and pullets for all traits studied.