Growth performance, nutrient digestibility and immune response of broiler chicks fed diets supplemented with a culture of Lactobacillus bulgaricus

BACKGROUND: Probiotics are being developed for use in animal feed to enhance production performance and prevention of gastrointestinal infections. The ban on using antibiotics as growth promoters, antibiotic resistance and the inherent problems of developing new vaccines make a compelling case for developing alternatives for in-feed antibiotics. The alternatives of choice have to be considered under the environmental conditions of the animal. Among the probiotics in use today, Lactobacillus has been shown to play a vital role in disease prevention, immune enhancement, improved growth and carcass yield in poultry. The present study investigates the effect of Lactobacillus bulgaricus (LB)-based probiotic on the growth performance, nutrient digestibility and immune response of broilers under tropical environmental conditions. RESULTS: Broilers fed LB diets consumed more feed (P < 0.05) and had greater body weight gain than the control group. Feed/gain ratio improved significantly (P < 0.05) with the 20, 40 and 60 mg kg(-1) LB diets compared with the control or 80 mg kg(-1) LB diet. The apparent digestibilities of nitrogen and fat increased with LB supplementation. However, there was no significant difference (P > 0.05) in fibre digestibility. White blood cell count increased significantly in broilers fed higher levels (> 40 mg kg(-1)) of LB compared with the control group. Antibody production measured as antibody titre against Newcastle disease vaccine showed a curvilinear response over the range of LB concentrations examined. CONCLUSION: The results indicate that LB addition to broiler chick diets significantly improved growth performance, increased nutrient digestibility and stimulated humoral immune response. (C) 2008 Society of Chemical Industry