COMPARATIVE EXCRETION AND RETENTION OF DDT ANALOGS BY DAIRY COWS

Three groups of three cows each were fed 25 mg of p,p′-DDT, p,p′-DDD, or p,p′-DDE per day for 60 days. Concentrations of the compounds in milk fat approached, but did not reach, equilibrium during the feeding period. From 40 to 60 days, 25.8% of the p,p′-DDE, 7.6% of the p,p′-DDD, and 5.1% of the p,p′-DDT as p,p′-DDT (2.1%) and p,p′-DDD (3.0%) were excreted in the milk. When the feeding of the compounds ended at 60 days, the decline in milk fat concentrations of all compounds could be described as the sum of two first-order terms. The initial partial concentrations of the first term were 0.41, 0.91, and 0.41 with rates of decline of 67, 41, and 31% per day for p,p′-DBT, p,p′-DDD, and p,p′-DDE, respectively. The initial partial concentrations of the second term were 0.59, 0.09, and 0.59, with rates of decline of 1.3, 2.6, and 1.3% per day, respectively. © 1969, American Dairy Science Association. All rights reserved.