Effects on growing swine and sheep of two polychlorinated biphenyls.

Dietary polychlorinated biphenyls in feeds at concentrations of 20 ppm given to swine and sheep between weaning and time of their reaching market weight reduced feed efficiency and rate of gain. These effects were of the same magnitude as those observed in swine and sheep fed sub-optimal diets, and in swine, there was a highly significant interaction between diet and polychlorinated biphenyl effects. Gross and microscopic lesions were few, consisting of increased frequency of pneumonia in swine and sheep and of increased frequency and severity of gastric lesions in swine. The gastric lesions in swine consisted of erosions of surface mucosa; these lesions were greater in the swine given the higher dose levels when they included hypertrophy, hyperplasia, and deep ulcerative lesions.