The Modulatory Effects of Lacticaseibacillus paracasei Strain NSMJ56 on Gut Immunity and Microbiome in Early-Age Broiler Chickens

SIMPLE SUMMARY: Feed additives have been used in the livestock industry because of their positive effect on animals, including broiler chickens. Recently, probiotics, which are one of the representative feed additives for antibiotic replacement, have been widely used due to the prohibition of the use of antibiotics in the livestock industry. Various beneficial effects of probiotic Lactobacillus spp. have been reported; however, to our knowledge, there are few studies related to their regulating effects on gut immunity and microbiome in early-age broiler chickens. In the present study, we performed a comparative animal study on gut immunity and gut microbiome in early-age broiler chickens fed either a control diet or Lacticaseibacillus paracasei NSMJ56-supplemented diet. Our results suggest that L. paracasei NSMJ56 has modulatory effects on the gut environment, such as gut immunity and microbiome, in early-age broiler chickens. ABSTRACT: Gut health has been attracting attention in the livestock industry as several studies suggest that it is a crucial factor for growth performance and general health status in domestic animals, including broiler chickens. Previously, antibiotics were widely used to improve livestock growth, but their use is now prohibited due to serious problems related to antibiotic resistance. Thus, finding new feed additives to replace antibiotics is drawing attention. Probiotics are representative feed additives and many beneficial effects on broiler chickens have been reported. However, many probiotic studies are focused on productivity only, and there are insufficient studies related to the gut environment, especially gut immunity and gut microbiome. In this study, we conducted an animal experiment using Lacticaseibacillus paracasei NSMJ56 to determine whether it has beneficial effects on gut immunity and microbiome. To evaluate the effects of NSMJ56 supplementation, newly hatched Ross 308 broiler chickens were fed an NSMJ56-containing diet for 10 days, and growth performance, antioxidant indicators, gut morphology, gut immunity-related parameters, and gut microbiome were analyzed. Flow cytometry analysis results revealed that NSMJ56 treatment increased CD4+ T cells and decreased CD8+ T cells in small intestine lamina propria and decreased IL1b and IL10 gene expression in small intestine tissue. In the microbiome analysis, NSMJ56 treatment increased the alpha diversity indices and led to three enriched genera: Massilimicrobiota, Anaerotignum, and Coprococcus. This study suggests that NSMJ56 supplementation has regulatory effects on gut immunity and microbiome in early-age broiler chickens.