Bacillus amyloliquefaciens spray improves the growth performance, immune status, and respiratory mucosal barrier in broiler chickens

ABSTRACT Studies have shown that supplementing probiotics in a nasal spray can provide prophylaxis against upper respiratory tract infections. Previously, we found that spraying with Bacillusreduced the concentration of atmospheric ammonia and airborne microbiological aerosols in broiler houses. In the present study, we evaluated the effects of spraying with Bacillus amyloliquefacienson the respiratory mucosal barrier in broilers. Two Trials were conducted simultaneously in four environmentally controlled chambers. In each trail, 320 1-d-old male broilers were randomly assigned to control (CON) and B. amyloliquefaciens(BAQ) group. Eight cages containing 20 birds per cage were placed in two chambers. The BAQ group chambers were sprayed with B. amyloliquefaciensat 4 × 109CFU/m2each day for 42 d. Spraying with B. amyloliquefaciensincreased average daily gain and average daily feed intake in broilers (P 0.05). The relative weights of the bursa (21 d) and spleen (42 d) were higher in the BAQ group (P