Aim: The aim of the study was to determine the potentials and effects of Bacillus subtilis and lactic acid bacteria (LAB) as probiotics on broiler growth, health, and Salmonella infection. Materials and Methods: To evaluate the inoculum size applicable for broilers, 1-day-old broilers were orally fed fresh cultures of single strains and a B. subtilis KKU213/Pediococcus pentosaceus NP6 mixture at 108 and 1012 colony-forming unit (CFUs)/mL/chick. The body weight gain (BWG), Salmonella contamination level and total Bacillus and LAB abundances in the crop and intestine were measured. Subsequently, 1-day-old broilers were orally fed of KKU213, CH403, and Pediococcus acidilactici SH8 at 1010 CFUs/mL, followed by inulin. After 35 days, the BWG, Bacillus and LAB abundances in the cecum, blood parameters, and KKU213 colonization were assessed. Results: The broilers fed single strains or KKU213+NP6 exhibited a higher BWG and a higher crop LAB abundance than the controls (p<0.05). Probiotic feeding decreased the intestinal Salmonella abundance and correspondingly increased the LAB abundance. The broilers fed the mixed culture (KKU213+CH403+SH8) followed by prebiotics showed lower mortality, higher blood high-density lipoprotein levels, and lower blood uric acid levels than the controls (p<0.0004). Probiotic feeding significantly increased the Bacillus and LAB counts (p<0.05). A CE330 isolate obtained from the cecum after 35 days of KKU213 feeding was closely related to B. subtilis KKU213. Conclusion: B. subtilis KKU213 is a potent probiotic strain that can survive, colonize and reduce Salmonella infection in broilers and improve their growth and health. This strain, combined with different LAB can act synergistically in the gut and promote broiler growth.

Background and Aim: Many strains of probiotics have been exploited and used as animal dietary supplements for broiler production. The efficacy and survival of probiotics during production may reflect better activities of the probiotics in the host. This study investigated the effects of freeze- and spray-drying on the survivability and properties of probiotics and their ability to improve the growth and health performance of broilers. Materials and Methods: Probiotic powders of four strains of lactic acid bacteria, Enterococcus faecium CA4, Enterococcus durans CH33, Ligilactobacillus salivarius CH24, Pediococcus acidilactici SH8, and Bacillus subtilis KKU213, were prepared using rice bran/chitosan/carboxy methyl cellulose as the carrier. The survival of each probiotic strain was investigated under stress conditions, including freeze-drying, spray-drying, and simulated gastrointestinal conditions. The body weight gain (BWG) and intestinal histomorphology were determined to assess broiler growth performance. Results: All dried probiotics yielded a high survival rate during freeze-drying (95.8-98.6%) and spray-drying (94.4-98.2%). In addition, an analysis of the main effect revealed that the effectiveness of freeze-drying was higher than that of spray-drying in minimizing the loss of cell viability. The antimicrobial activity of all immobilized dried probiotic strains against Salmonella was maintained. The immobilized probiotics tolerated a low pH value of 2.0 and 0.5% (w/v) bile salt. Probiotic administration of a mixture of the five dried probiotics to 1-day-old hatched male broilers at early and late ages resulted in potential colonization in the broiler intestine, and enhancements in the BWG, lipid metabolism, and gut health (villus height and cryptal depth) were observed in the probiotic-treated groups. Conclusion: The administration of three doses of the spray-dried probiotic mixture at days 15, 17, and 19 after hatching was sufficient to achieve long-term growth and health benefits in broilers. This finding might provide a cost-effective alternative to the administration of commonly used antibiotics in broiler production. Keywords: broilers, growth performance, immobilized probiotics, intestinal morphology, lactic acid bacteria.