The aim of this study was to determine the effects of dietary lycopene supplementation on growth performance and antioxidant status of broiler chickens exposed to cold environment to induce ascites. Three hundred male chickens were exposed full-day to cold stress (CT, 10°C) starting from day 15 of age until the end of experiment at day 42, while a positive control group (NT, 100 birds) was kept under normal temperature (23-25°C). The CT groups (three treatments and five replicates of 20 birds) were as follows: negative control (basal diet, CT) and CT + 200 or 400 mg lycopene per kg diet from 15 to 42 d of age. Results showed that CT without lycopene supplementation caused a reduction of feed intake and weight gain and increased the feed conversion ratio. Supplementation of lycopene during CT restored the performance to levels of the positive control, lowered the index of right ventricles/total ventricles and ascites mortality. Birds reared under CT had lower serum activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and higher malondialdehyde (MDA) concentration than birds reared under the NT environment. With lycopene supplementation, serum MDA level significantly decreased and the activity of SOD and GPx increased. Blood concentration of haematocrit, haemoglobin and red blood cells were decreased by the highest lycopene supplementation to a level comparable to NT. Moreover, increasing dietary lycopene level suppressed serum concentrations of cholesterol and enhanced high-density lipoproteins levels in blood. In conclusion, lycopene supplementation alleviates adverse effects of cold stress on performance through modulating activity of antioxidant enzymes in broiler chickens.
Keywords: Antioxidant properties; ascites; blood lipids; broilers; cold stress; lycopene; performance.