Evaluation of changes in tonic immobility, vigilance, malondialdehyde, and superoxide dismutase in broiler chickens administered fisetin and probiotic (Saccharomyces cerevisiae) and exposed to heat stress

Abstract

The study evaluated changes in tonic immobility (TI), vigilance behavior, malondialdehyde (MDA), and superoxide dismutase (SOD) in broiler chickens administered fisetin and probiotic. Sixty Arbor Acre breed of broiler chickens at day old, allotted into 4 groups of 15 birds each, were used. Group I (control) was given only sterile water; group II, fisetin (5 mg/kg); group III, probiotic (4.125 × 106 cfu/100 mL); and group IV, fisetin + probiotic. At weeks 3, 4, and 5, thermal environment parameters, TI and vigilance behavior, were recorded each day at 07:00 h, 13:00 h, and 18:00 h. The vigilance at self-righting during each TI test was observed in broiler chickens and ranked as (1) fearlessness, (2) slightly fearful, and (3) fearfulness. MDA concentration and SOD activity in breast muscle were determined using a spectrophotometer. Temperature-humidity index (25.55-35.30) was outside the thermoneutral zone (20.8) for broiler chickens above 3 weeks of age. Week 3 had the longest (P < 0.05) duration of TI in the controls, but the shortest (P < 0.05) duration was recorded in the fisetin + probiotic group. At week 4, the shortest (P < 0.05) TI duration was recorded in the probiotic-supplemented group, while the longest (P < 0.05) TI was obtained in the control group. The shortest (P < 0.05) TI duration was recorded at week 5 in the probiotic and fisetin + probiotic groups, compared with that of the controls. The highest (P < 0.05) TI duration was recorded at 13:00 h in the controls, but the shortest (P < 0.05) was obtained at 18:00 h in the probiotic and fisetin + probiotic groups. At week 3, the vigilance behavior ranking recorded in the probiotic, fisetin + probiotic, and fisetin broiler chickens were lower (P < 0.05) than that obtained in the control group, which was the highest. At week 4, the highest (P < 0.05) vigilance behavior ranking was obtained in the control group. At week 5, the lowest (P < 0.05) vigilance behavior ranking was recorded in the probiotic-supplemented group, but the highest (P < 0.05) value was obtained in the control group. At 7:00, 13:00, and 18:00 h, there was no significant difference (P > 0.05) in the vigilance behavior ranking in the control, fisetin, probiotic, and fisetin + probiotic groups of broiler chickens. The MDA concentration in broiler chickens administered probiotic, either alone or in combination with fisetin, was lower (P < 0.05) compared with that of the controls. The activity of SOD was higher (P < 0.05) in fisetin + probiotic broiler chickens than in the control group. Probiotic and/or fisetin ameliorated the behavioral stress response in the broiler chickens via oxidative stress mechanism, as evidenced by increase in SOD activity and decrease in MDA concentration in the breast muscle of the chickens. In conclusion, administration of probiotic, either alone or in combination with fisetin, decreased duration of TI and vigilance behavior ranking, increased SOD activity, and lowered MDA concentration in broiler chickens exposed to heat stress.