Bacillus licheniformis (B. licheniformis) is a safe probiotic that can promote animal growth and inhibit pathogenic bacteria. This study aimed to assess the effects of B. licheniformis, one green feed additive, on growth performance, diarrhea incidence, immune function, fecal volatile fatty acids, and microflora structure in weaned piglets. Weaned piglets (n = 180) were randomly divided into three treatment groups and fed a basal diet and a basal diet supplemented with 500 mg B. licheniformis per kg and 1000 mg B. licheniformis per kg, respectively. The dietary 500 mg/kg B. licheniformis inclusion improved the average daily gain, reduced diarrhea incidence, and strengthened antioxidant capacity. Piglets supplemented with B. licheniformis presented increased serum immunoglobulins (IgA, IgM) compared to the CON group. Meanwhile, the expression of anti-inflammation factors was increased, and the levels of pro-inflammation factors were reduced after B. licheniformis administration. Moreover, the levels of volatile fatty acids, including acetic acid, propionic acid, butyric acid, isobutyric acid, and isovaleric acid, in the BL500 and BL1000 groups were increased compared with the CON group, and the concentration of valeric acid was higher in the BL500 group. Furthermore, piglets in the 500 mg/kg B. licheniformis addition group significantly altered fecal microbiota by increasing Clostridium_sensu_stricto_1 and Oscillospira. In conclusion, dietary B. licheniformis relieved diarrhea, enhanced antioxidant capacity, immunity function, and fecal microflora structure in weaned pigs.

The purpose of this study is to investigate the effects of Yucca saponin (YSa), Yucca schidigera (YS), and Quillaja Saponaria (QS) on growth performance, nitrogen metabolism, immune ability, antioxidant capability, and intestinal flora of yellow-feather broilers. This study randomly divided a total of 480 1-day yellow-feather broilers into 4 treatment groups. Factors in the 4 groups included CON group (basic diet), YSa group (basic diet mixed with 500 mg/kg YSa), YS group (basic diet mixed with 500 mg/kg YS), and QS group (basic diet mixed with 500 mg/kg QS). Throughout the 56-day study period, YSa, YS, and QS groups had higher average daily gain in broilers than the CON group (p < 0.01). The YS group had a lower feed gain ratio (F: G) in broilers than the CON group (p < 0.05). YSa, YS, and QS showed increased serum immunoglobin A (IgA), immunoglobin Y (IgY), immunoglobin M (IgM), and total antioxidant capacity (T-AOC) levels; enhanced acetic acid, butyric acid, and valeric acid levels of cecal content; and reduced contents of ammonia nitrogen, urea nitrogen, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and malondialdehyde (MDA) in serum in broilers (p < 0.05). The relative abundance of Lachnoclostridium in the QS group was decreased compared with that in the CON group (p < 0.05). Higher IgA and IgY sera contents were observed in the YS group compared to the YSa and QS groups (p < 0.05). In contrast with the QS group, the serum IL-6 concentration of the YS group was reduced (p < 0.05). In conclusion, YSa, YS, and QS promoted growth performance, nitrogen metabolism, immunity, antioxidant capability, and intestinal flora in broilers. Through the comparison of YSa, YS, and QS, it was found that YS is more suitable as a feed additive to ameliorate the healthy growth of broilers.

This research study aimed to investigate the effects of Lactiplantibacillus plantarum (L. plantarum) on growth performance, oxidation resistance, immunity, and cecal microbiota in broilers. This work classed three hundred and sixty 1-day-old male broilers into three groups randomly, including a control group (CON, basal diet) and antibiotic (ANT, 75 mg kg⁻¹ chlortetracycline added into basal diet) and probiotic groups (LP, 5 × 10⁸ CFU kg⁻¹Lactiplantibacillus plantarum HJLP-1 contained within basal diet). Animals were then fed for 42 days, and each group comprised eight replicates with 15 broilers. Compared with CON, L. plantarum supplementation significantly improved the average daily weight gain (AWDG) (p < 0.05) while reducing the feed–gain ratio over the entire supplemental period (p < 0.05). Birds fed L. plantarum had markedly lower serum ammonia and xanthine oxidase levels (p < 0.05) than those in the ANT and CON groups. Significant improvements (p < 0.05) in superoxide dismutase, catalase, and serum IgM and IgY contents in broilers fed L. plantarum were also observed when compared with those in the CON and ANT groups. Both L. plantarum and antibiotics decreased pro-inflammatory factor IL-1β levels significantly (p < 0.05), while only L. plantarum promoted anti-inflammatory factor IL-10 levels in the serum (p < 0.05) compared with CON. L. plantarum (p < 0.05) increased acetic acid and butyric acid concentrations in cecal contents when compared to those in CON and ANT. Among the differences revealed via 16S rRNA analysis, L. plantarum markedly improved the community richness of the cecal microbiota. At the genus level, the butyric acid-producing bacteria Ruminococcus and Lachnospiraceae were found in higher relative abundance in samples of L. plantarum-treated birds. In conclusion, dietary L. plantarum supplementation promoted the growth and health of broilers, likely by inducing a shift in broiler gut microbiota toward short-chain fatty acid (SCFA)-producing bacteria. Therefore, L. plantarum has potential as an alternative to antibiotics in poultry breeding.

Our study aimed to explore the effects of postbiotics on protecting against Salmonella infection in mice and clarify the underlying mechanisms. Eighty 5-week-old C57BL/6 mice were gavaged daily with Lactiplantibacillus plantarum (LP)-derived postbiotics (heat-killed bacteria, LPB_inactive; culture supernatant, LPC) or the active bacteria (LPB_active), and gavaged with Salmonella enterica Typhimurium (ST). The Turbidimetry test and agar diffusion assay indicated that LPC directly inhibited Salmonella growth. Real-time PCR and biofilm inhibition assay showed that LPC had a strong ability in suppressing Salmonella pathogenicity by reducing virulence genes (SopE, SopB, InvA, InvF, SipB, HilA, SipA and SopD2), pili genes (FilF, SefA, LpfA, FimF), flagellum genes (FlhD, FliC, FliD) and biofilm formation. LP postbiotics were more effective than LP on attenuating ST-induced intestinal damage in mice, as indicated by increasing villus/crypt ratio and increasing the expression levels of tight junction proteins (Occludin and Claudin-1). Elisa assay showed that LP postbiotics significantly reduced ST-induced inflammation by regulating the levels of inflammatory cytokines (the increased IL-4 and IL-10 and the decreased TNF-α) in serum and ileum (p < 0.05). Furthermore, LP postbiotics inhibited the activation of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome by decreasing the protein expression of NLRP3 and Caspase-1, and the gene expression of Caspase-1, IL-1β and IL-18. Meanwhile, both LPC and LPB observably activated autophagy under ST infection, as indicated by the up-regulated expression of LC3 and Beclin1 and the downregulated p62 level (p < 0.05). Finally, we found that LP postbiotics could trigger an AMP-activated protein kinase (AMPK) signaling pathway to induce autophagy. In summary, Lactiplantibacillus plantarum-derived postbiotics alleviated Salmonella infection via modulating bacterial pathogenicity, autophagy and NLRP3 inflammasome in mice. Our results confirmed the effectiveness of postbiotics agents in the control of Salmonella infection.