Effect of Levels and Different Periods of Vitamin Premix Consumption during Finisher Period on Performance and Immunocompetence of Broiler Chicks fed Wheat and Barley Based Diet

The purposes of this study were to estimate the effect of levels and different periods of vitamin premix consumption during finisher period (29-42 d) on performance and immunocompetence of broiler chicks fed wheat and barley based diet in floor system. A total of 504 male broiler chicks (Ross 308) were allocated to 7 treatment groups, with 4 replicates per treatment group and 18 birds per replicate pen, and all data were analyzed in a randomized complete design. The dietary treatments were: T1) the basal diet with no vitamin premix during 29-42 days; T2) the basal diet 33.33% vitamin premix during 29-42 days; T4) the basal diet 66.66% vitamin premix during 29-42 days and T6) 100% vitamin premix during 29-42 days and treatments 3, 5 and 7, similar treatments 2, 4 and 6 grespectively and fed during 24-35 day and the vitamin premix was with drawn from all these lates diets (35 and 7) during 36-42 day of age. Feed intake and weight gain were measured at 3 and 42 days of ages and feed conversion ratio was calculated. At 35 and 42 days of ages, after slaughtered and determine carcass weight and the organs bursa of fabricius and spleen were weighed and immunocompetence was evaluated at 42 day of age, based on SRBC, IgG and IgM titers by hemagglutination method. Results showed that different levels of vitamin premix did not impair performance and immunocompetence response during the final period of broilers (29-42d). In conclusion, it is possible to withdraw vitamin premix from finisher diets.