[Dynamics of exogenous progesterone in the blood of pigs stressed with polychlorobiphenyls (PCB)].

For a period of 70 days, young gilts were given rations containing a commercial mixture of polychlorinated biphenyls (PCB), produced in Czechoslovakia (Delor 105). One group of animals (A) was given feed containing 10 mg chlorobiphenyls per kg, the other group (B) was given feed containing 50 mg chlorobiphenyls per kg; on the whole, each animal of group A got 1 g of PCB mixture and each animal of group B 5 g. In about the mid-time of the experiment and before its termination the animals were given an i. m. injection of progesterone; then the animals were studied for the changes in the concentration of blood plasma progesterone. Statistically significant (P less than 0.05) and highly significant (P less than 0.01) differences in the values of the biological half-life of progesterone were found between the group of PCB-treated animals and the control group, and between groups A and B.