This study was conducted to investigate effects of dietary Limosilactobacillus fermentum and Lacticaseibacillus paracasei supplementation on the intestinal stem cell proliferation, immunity, and ileal microbiota of broiler chickens challenged by coccidia and Clostridium perfringens. A total of 336 one-day-old Ross 308 chickens were randomly assigned into four groups. Chickens in the control (CTR) group were fed basal diet, and chickens in the three challenged groups were fed basal diets supplemented with nothing (CCP group), 1.0 × 109 CFU/kg L. fermentum (LF_CCP group), and 1.0 × 109 CFU/kg L. paracasei (LP_CCP group), respectively. All challenged birds were infected with coccildia on day 9 and Clostridium perfringens during days 13-18. The serum and intestinal samples were collected on days 13 and 19. The results showed that L. fermentum significantly increased jejunal gene expression of cdxB (one of the intestinal stem cell marker genes) on day 13. Additionally, L. fermentum significantly up-regulated mRNA levels of JAK3 and TYK2 and tended to increase STAT6 mRNA expression in jejunum on day 19. In the cecal tonsil, both L. fermentum and L. paracasei decreased mRNA expression of JAK2 on day 13, and L. fermentum down-regulated JAK1-2, STAT1, and STAT5-6 gene expressions on day 19. Ileal microbiological analysis showed that coccidial infection increased the Escherichia-Shigella, Lactobacillus, and Romboutsia abundance and decreased Candidatus_Arthromitus richness on day 13, which were reversed by Lactobacillus intervention. Moreover, Lactobacilli increased ileal Lactobacillus richness on day 19. In conclusion, Lactobacilli alleviated the impairment of intestinal stem cell proliferation and immunity in coccidia- and C. perfringens-challenged birds via modulating JAK/STAT signaling and reshaping intestinal microflora.
Keywords: Lacticaseibacillus paracasei; Limosilactobacillus fermentum; broiler chicken; intestinal health; necrotic enteritis.