Abstract

Background and Objectives: Tsukamurella species are Gram-positive rods that exist in a broad range of environments. In this study, the efficacy of heat-killed Tsukamurella inchonensis on growth performance, intestinal morphology, and humoral immune responses of broiler chicken was evaluated.Materials and Methods: Ross broiler chicks in the cage were randomly allocated to five groups. Trail diets were prepared by adding 106 cells per bird of heat-killed T. inchonensis into the basal trading diet for group 1 continuously dosed for 24 h from day 1 to day 13, and for group 2, 24 h on days 1 to 5; 8; 9, 12 and 13. Group 3 was received 10 6 bacteria as a subcutaneous injection on days 1, 6, and 12. Groups 4 and 5 were not received T. inchonensis during the experiment period.Results: Feed intake (FI) and feed conversion ratio (FCR) were not altered by different delivery methods of T. inchonensis supplementation. The pulsed dosed in feed tended to provide higher body weight gain (BWG) than the negative control groups. T. inchonensis treatments, never less of the ways of delivery, boosted (P<0.05) the antibody titers to Newcastle disease virus (NDV), and avian influenza (AI) (H9N2) virus, especially when broiler chickens treated with pulse dosed in the feed. The most significant intestinal development (p<0.05) was observed between groups 1 and 2. There were no significant differences in the thymus, liver, and bursa of Fabricius relative weight. Still, there were significant increases in the relative weight of spleen on day 14 in vaccinated chickens treated with T. inchonensis pulse dosed.Conclusion: It seems that the supplementation of T. inchonensis in the broiler diet can improve intestinal morphology and humoral immune response, which was represented by increased antibody response to NDV, and AI vaccines significantly, but it cannot affect FI and FCR.