Evaluation of dietary probiotic (Bacillus subtilis KMP-BCP-1 and Bacillus licheniformis KMP-9) supplementation and their effects on broiler chickens in a tropical region

The experiment aimed to investigate the effects of probiotic (Bacillus subtilisKMP-BCP-1 andBacillus licheniformisKMP-9) supplementation on growth performance, ileal digestibility, jejunal histomorphology, colonic ammonia-nitrogen (NH3-N) and blood parameters in broiler chickens. A total of 288, one-day-old female Ross-308 broilers were randomly allotted into 4 treatments with 6 replicates of 12 birds. Treatments were (T1) basal diet (BD), (T2) BD with 200 ppm amoxicillin, (T3) and (T4) BD with probiotics at the levels of 2.5 x 10(7)and 5.0 x 10(7)cfu/kg feed, respectively. Supplementation of amoxicillin or probiotics improved (P < 0.05) average daily gain (ADG) and feed conversion ratio (FCR) on d 42. Compared to those fed with T1, broilers fed with T4 increased (P < 0.05) the ratio of jejunal villus height to crypt depth, and improved (P < 0.05) ileal digestibility of dry matter and protein. They also had the highest numbers of lactic acid bacteria (LAB) andBacillusspp. as well as the ratio of LAB toEscherichia coli(P < 0.05). Probiotics at the level of 5.0 x 10(7)cfu/kg feed improved the growth performance of broilers in a tropical region by enhancing the balance of caecal bacteria, jejunal histomorphology and ileal digestibility.