The present study aimed to investigate the effect of probiotic lactic acid bacteria (LAB) addition on Listeria monocytogenes translocation and its toxin listeriolysin O (LLO), proinflammatory factors, immune organ indexes and serum immunoglobulins in farmed rabbits. Five treatments included negative control (NC), positive control (PC) with L. monocytogenes infection and supplemental LAB at 3.0 × 10⁶(low-LAB, L-LAB), 3.0 × 10⁸ (medium-LAB, M-LAB) and 3.0 × 10¹⁰(high-LAB, H-LAB) CFU/kg of diet, respectively. The LAB was a mixture of equal amounts of Lactobacillus acidophilus (ACCC11073), Lactobacillus plantarum (CICC21863) and Enterococcus faecium (CICC20430). A total of 180 weaned rabbits (negative for L. monocytogenes) were randomly assigned to 5 groups with 6 replicates of 6 rabbits each in response to the 5 treatments. L. monocytogenes infection occurred on the first day of feeding trial and dietary LAB supplementation lasted for 14 days. The results showed that on days 7 and 14 post administration, L. monocytogenes in caecum, liver, spleen and lymph nodes was reduced in M-LAB and H-LAB compared to PC (P < 0.05), and linear and quadratic reducing trends were found in liver on day 7 (P ≤ 0.002). On day 14, mucosa LLO mRNA expression and serum TNFα, IL1β and IFNγ were reduced in the three LAB treatments (P < 0.05), and linear and quadratic trends were found on TNFα and IL1β (P ≤ 0.025); indexes of thymus and spleen, serum IgA and IgG were increased in the LAB treatments (P < 0.05). It is concluded that LAB can be used to alleviate L. monocytogenes infection and to improve the immune function of farmed animals.

Artemisia vulgaris (A. vulgaris) is an edible plant showing antioxidant and antibacterial effects, but its effect as a feed additive or forage source on the herbivore growth and health is unclear. This study aimed to investigate the effect of A. vulgaris meal supplementation on the growth performance, gut microbes, and immune function in rabbits. A total of 120 growing Rex rabbits were randomly allocated into 4 treatments with 6 replicates per 5 rabbits each. There were four experimental diets containing A. vulgaris meal at doses of 0, 3.0, 6.0 or 9.0%, respectively. The experiment lasted for 70 days. The results showed that diets supplemented with A. vulgaris meal improved the rabbits’ feed intake, body weight gain, and decreased feed conversion ratio (P < 0.05). Linear and quadratic responses were found between the growth parameters and the herbal meal doses (P ≤ 0.002). A. vulgaris meal also improved gut microbe populations by increasing Lactobacilli and Bifidobacteria, and decreasing E. coli, C. perfringens, Salmonella, and Gram-negative bacteria (P < 0.05), and linear and quadratic dose-dependent advantages were exhibited for these microbes (P ≤ 0.013). Furthermore, blood levels of IgA, IgM, and lymphocytes of bursale, thymus, CD4 and CD8 were increased by the treatments containing A. vulgaris meal (P < 0.05), and linear dose-dependent effect was found on these immune indexes (P < 0.001). Diet supplemented with A. vulgaris meal is effective in improving growth, gut microbes, and immunity of Rex rabbits.