Abstract
This research aims at studying the effects of adding green tea and vitamin E on the performance, blood
parameters, immune system, visceral traits, and blood cells in broilers under dexamethasone stress. In this
experiment, 210 male broiler chicks were studied by completely randomized block design in 7 treatments,
and each group with three replications (each replication with 10 male chicks). Treatment groups, include
group 1: control (basic diet, without adding green tea and vitamin E, and no dexamethasone injection),
group 2( with green tea and dexamethasone injections, without adding vitamin E), group 3(with addition
of 300 mg/kg of vitamin E, without dexamethasone injection and consumption of green tea), group 4(a
basic diet containing 1.5% green tea, without vitamin E and dexamethasone injections), group 5(a basic
diet containing 300 mg/kg of vitamin E and dexamethasone injection without adding green tea), group
6(basic diet with 1.5% green tea with dexamethasone injection, without adding vitamin E.), and group
7(Basic diet taking 1.5% of green tea and 300 mg/kg of vitamin E with dexamethasone injection).
Dexamethasone was injected twice in two stages during the 31th and 33th days for the first time and at 37th
and 40th days for the second time of breeding. The minimum feed consumption was observed by green
tea, and the maximum feed consumption was observed in the control group with the dexamethasone and
vitamin E taking group (P<0.05). The maximum weight gain in the initial growth, growth, and final
growth stages were in the control group and the minimum weight gain was in a group of 1.5% added
green tea and dexamethasone groups (P<0.05). In this study, consumption of green tea reduced the
performance through its effect on reducing feed consumption. Therefore, broilers' weight was reduced.
Using dexamethasone as a stressful factor harmed the performance of broilers. Adding the green tea to the
blood biochemical parameter reduced blood cholesterol and LDL (P<0.05). Blood cholesterol reduction
was observed by the impact of adding green tea to the diet.