The increasing recognition of the potential advantages beyond nanoencapsulation of probiotics has gained great attention owing to their effective properties. Hence, we provided the most in-depth look into the influence of nanoformulated multistrain probiotics (BLB-NPs), comprising Bacillus subtilis ATCC 19659, Lactobacillus plantarum ATCC 8014, and Bifidobacterium bifidum ATCC 29521, on growth performance, antioxidant status, and intestinal immunity, supporting the defense against Salmonella Typhimurium (S. Typhimurium) challenge in broiler chickens.
A total of 2,800 one-day-old male Ross 308 broiler chicks were divided into 7 groups: (1) control without additives, (2-4) three probiotics groups (fed control diets mixed with B. subtilis, L. plantarum, and B. bifidum (BLB) at concentrations of 1×10⁴ (BLB-I), 1×10⁶ (BLB-II), and 1×10⁸ (BLB-III) CFU/kg diet, respectively), and (5-7) three nanoencapsulated probiotics groups (fed control diets supplemented with BLB-loaded nanoparticles (BLB-NPs) at concentrations of 1×10⁴ (BLB-NPs-I), 1×10⁶ (BLB-NPs-II), and 1×10⁸ (BLB-NPs-III) CFU/kg diet, respectively). All groups were challenged at day 22 of age with S. Typhimurium.
Birds fed BLB-NPs-II and III exhibited better weight gain and feed conversion ratio (FCR), along with upregulation in nutrient transporter genes (*LAT-1, PepT-1, CAT-1*, and SGLT1), even after S. Typhimurium challenge. Upregulation of immune-related genes (*IL-1β, IL-6, IL-8, MyD88, NF-κB, CCL20, CXCLi2, TLR-2, TLR-4*, and SOCS1) was prominently subdued in the BLB-NPs-III-fed group. The strengthening ability of BLB-NPs for broilers’ intestinal barriers was evidenced by augmented expression of *JAM, MUC-2, occludin*, and *FABP-2* genes, diminished S. Typhimurium counts, and suppressed its virulence-related genes (HilA and SopD), along with restored histopathological pictures of the cecum.
Notably, after dietary inclusion of higher levels of BLB-NPs-III, the abundance of beneficial Bifidobacterium and Lactobacillus species dominated over harmful E. coli ones. Birds fortified with BLB-NPs displayed potent antioxidant potential, signified by boosting serum and intestinal antioxidant markers while reducing oxidative ones.
Overall, the abovementioned positive outcomes of BLB-NPs encourage their potential application in poultry feed to attain superior performance and elicit protective immunity against S. Typhimurium infection.