[Effect of DDT, intensive use of the floor surface and post-incubation stress on the development of immune response in chickens].

We studied the long-term effect of civilization factors, DDT, high stocking rates, and post-incubation stress on the antibody response to the administration of Newcastle disease vaccine. The chickens were divided into three groups after hatching. The first group was fed a mixture with an addition of commercial DDT (100 mg per 1 kg of feed). The second group was given the same feed and, in addition, was kept at a high stocking rate. Half the experimental chickens of each group were tied in the third post-natal week, to subject the birds to another stress. Those in the control group remained intact. The results indicate that DDT administered with food increased the immunity response to the antigen stimulus. The additive stress from high stock densities reduced the immunity response, and decreased the response raised by DDT administration to the level of the control. The post-incubation stress was found to modify the long-term effect of DDT and high stocking rate upon the immunity response of the chickens.