The effect of the addition of green tea and fish oil to diet of broiler on the performance and response of humoral immunity against Newcastle

In order to study the effect of green tea and fish oil on performance and antibody titer against Newcastle disease, 405 day-old broiler chickens were evaluated in a 3×3 factorial experiment using completely randomized design. Chicks were divided into 9 parts and each part was split into 3 groups. Each part was fed by diet containing 0% (T0), 0.75% (T0.75) or 1.5% (T1.5) dry powder of green tea and 0% (F0), 0.75% (F0.75) or 1.5% (F1.5) fish oil. Feed intake, gain weight and feed conversion ratio were estimated weekly. The vaccine of Newcastle was inoculated at 8 and 17d. To assay the antibody of Newcastle by HI test, blood samples were collected from five checks of each group from brachial vein at 25, 32 and 39 d. The results showed that there was no difference between treatments on the feed conversion ratio (P>0.05) and the lowest weight gain (30.43) and the highest feed intake (72.25) were observed by 1.5% fish oil and 1.5% green tea. At 39 d, the highest level of antibody (3) was obtained by 1.5 % fish oil (P<0.05). At 32 and 39d, the levels of antibody against Newcastle was lower in 1.5% green tea (2.09 and 2.18, respectively) than 0% green tea (2.64 and 2.84, respectively; P<0.05). Therefore, the addition of 1.5% fish oil and 1.5% green tea to diet of broiler chickens increased and decreased the humoral immunity responses against Newcastle disease, respectively.