Effect of on the microarchitectural development of the immune system in -challenged broiler chickens.

The effect of  on the immune responses and morphometry of the immune organs was evaluated in broilers challenged with . For this purpose, -free birds ( = 240) were split into four groups with six replicates of ten birds each. Groups included an NC (negative control, non-infected + non-medicated), a PC-S (positive control, -infected + non-medicated), an AT-S (-infected + medicated with enrofloxacin), and a BS-S (-infected +  (2.0 × 10 cfu/g; 0.1 g/kg) group. On day 21, the thickness of the thymus cortex and medulla, germinal centre area of the spleen, bursal follicular length and bursal follicular area increased ( < 0.05) in the BS-S when compared to the NC and PC-S groups. On day 35, the BS-S group exhibited a higher ( < 0.05) antibody titre against the Newcastle disease virus (NDV), and cortex of the thymus was thicker ( < 0.05) compared to the other groups. A decrease in the thymus medulla thickness, germinal area of the spleen and bursal follicular number were noted in the PC-S group when compared to the other treatment groups. In conclusion, the prophylactic use of  type probiotics alleviated the stress resulting from a  infection and improved the immune organs development and function in infected broilers.