Feeding with Single Strains Versus Mixed Cultures of Lactic Acid Bacteria and Bacillus subtilis KKU213 Affects the Bacterial Community and Growth Performance of Broiler Chickens

Abstract

This study sought to isolate lactic acid bacteria (LAB) from chicken intestines and caeca and apply them as probiotics in broilers. Out of the 247 isolates, 14 LAB were selected based on their tolerance to pH 3 and 0.5% bile salt conditions and were tested against Salmonella serovars using two assay methods: (1) bacterial cells and double layers and (2) cell-free supernatants and agar well diffusion. The chicken isolates CA4, CH24 and CH33 strongly inhibited Salmonella Typhimurium ATCC13311 and S. Enteritidis. The selected strains were identified via 16S rDNA sequencing as Enterococcus faecium CA4, Enterococcus durans CH33 and Lactobacillus salivarius CH24. Only CH33 survived in simulated gastric juice and intestinal juice with survival rates of 90 and 18%, respectively. All three chicken LAB strains as well as food-originating Pediococcus acidilactici SH8 and bacteriocin-producing Bacillus subtilis KKU213 were tested in broilers. Single strains and mixed cultures of KKU213 and the four LAB strains were orally fed to 1-day-old male Cobb broilers, which were then raised for 45 days. Broilers fed LAB strains demonstrated higher numbers of LAB than the groups fed only B. subtilis KKU213 or mixed cultures. Among all treatments, the broilers fed B. subtilis KKU213 on days 1 and 3 and LAB on day 5 (T8) had the highest body weights and high-density lipid levels and the lowest uric acid levels. Therefore, a combination of bacterial species originating from various sources exhibits potential as a probiotic mixture to promote health in broilers.