Abstract
We investigated the effects of replacing raw soybean meal (RSM) with autoclaved soybean meal (ASBM) and fermented soybean meal by Lactobacillus plantarum (FSBMLP) and Bacillus pumilus (FSBMBP) on the performance, microbial population, intestinal morphology, immune system, and PepT1 gene expression in broiler chickens. One-day-old male Ross 308 broiler chicks (n = 800) were utilized in a fully randomized design featuring eight treatments and 5 replicates, and each replicate consisted of 20 chicks. The experimental treatments included: 1) a control group ([RSM]-based diet), 2) a basal diet + ASBM, 3) a basal diet + 2% FSBMLP, 4) basal diet + 4% FSBMLP, 5) basal diet + 6% FSBMLP, 6) basal diet + 2% FSBMBP, 7) basal diet + 4% FSBMBP, and 8) basal diet + 6% FSBMBP. The results showed significant improvements in feed conversion ratio and body weight gain throughout the experiment for broiler chickens receiving various FSBMLP levels and 4% and 6% FSBMBP compared to the controls (P < 0.05). The group receiving 6% FSBMLP also demonstrated significantly higher antibody titers against Newcastle disease virus and Gumboro disease, along with increased IgG and total immunoglobulin levels in response to sheep red blood cells, compared to the controls (P < 0.05). Additionally, the Lactobacillus population in the ileum and villus height in the jejunum were significantly higher in chickens fed FSBMLP than in the control group (P < 0.01). Furthermore, chickens fed 6% FSBMLP showed a significant increase in PepT1 gene expression compared to the control group (P < 0.05). Overall, the results suggested that replacing 6% of RSM with FSBMLP in broiler chicken diets improved growth performance, immune function, intestinal health, and PepT1 gene expression compared to ASBM and FSBMBP.