The effect of Aroclor 1254 (mixture of several polychlorinated biphenyls, PCBs) on chicken embryogenesis and hatching process was investigated. Aroclor 1254 was injected in ovo at the 4th d of embryogenesis at doses of 0 (control), 10, 100, 1,000 ng/egg (n=120 eggs/group). The incubation was carried out under standard conditions. Course of hatching was recorded for each group. Blood samples were collected from ten one-day-old chickens, which were randomly chosen from each group. Following blood sampling, the chicks were decapitated, and their livers and hearts were weighed. Thyroxine (T₄) and triiodothyronine (T₃) concentrations in blood plasma were determined by RIA method. In ovo injection of Aroclor 1254 did not affect the final rate of hatching. There was no influence of the PCB mixture on body weight and weight of the liver and heart. The compound injected at doses of 10 and 100 ng/egg did not affect T₄ concentrations; however, the highest dose of the PCB mixture decreased its level by 37% (P≤0.05). Aroclor 1254 at a dose of 10 ng/egg decreased by 20% T₃ concentration while at a dose of 1,000 ng/egg elevated the concentration of this hormone by 17% (P≤0.05). The data presented suggest that injection of PCBs mixture in ovo at the early stages of embryogenesis affects embryonic development and influences thyroid hormone concentration in blood plasma in one-day-old chickens.
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