Growth performance and immune response of broilers fed probiotic-supplemented diets

Abstract:

Can supplementing broiler diets with multi-strain probiotics improve both growth metrics and humoral immunity under commercial rearing conditions? This research addressed that question through a 35-day feeding trial conducted at the Federal University of Viçosa poultry research unit in Viçosa, Brazil, during March-April 2023. A total of 240 day-old Cobb 500 broiler chicks were randomly allocated to four treatment groups (T0, T1, T2, T3) of 60 birds each, with three replicates per group. The control group (T0) received a standard corn-soyabean meal basal diet, while T1, T2, and T3 received the same basal diet supplemented with a commercial multi-strain probiotic at 0.5, 1.0, and 1.5 g/kg feed, respectively. Weekly records of body weight, feed intake, and feed conversion ratio were maintained. Blood samples collected on day 35 were analysed for Newcastle disease antibody titres, serum IgG, and IgM concentrations. Birds on T2 and T3 diets had significantly higher final body weight (2047.9 g and 2063.2 g) compared with T0 (1842.1 g; p < 0.05). Feed conversion ratio improved by 8.3% in T2 relative to control. Serum IgG levels rose by 19.7% in T2 birds, and ND antibody titres were markedly elevated in all probiotic groups. Results point to 1.0 g/kg as a cost-effective inclusion level that enhances both growth and immune competence in commercial broilers.