RESUMEN
Antibiotics have been widely used for the prevention and the treatment of diseases to humans and animals, and they have fed additives for agricultural animals to promote growth. However, there is a growing concern over the practice due to its side effects on intestinal microbial communities which plays a vital role in animals' health. To investigate the effect of antibiotics on the bacterial population of the caecum in rex rabbits, 80 rex rabbits were randomly divided into four groups: control group (B, basal diet), chlortetracycline group (C, 50 mg/kg), colistin sulfate group (S, 20 mg/kg) and zinc bacitracin group (Z, 40 mg/kg). Caecum microbial communities of rex rabbits from the four groups were analyzed through Illumina Miseq platform after being fed 28 days. The results showed that most obtained sequences belongs to Firmicutes followed by Bacteroidetes, and the ratio of Bacteroidetes/Firmicutes in C group (42.31 %) was higher than that in Z group (21.84 %). Zinc bacitracin supplementation caused a significant decreased of the Proteobacteria phylum and Lactobacillus spp. (P < 0.05), while the Lactobacillus spp. significantly increased in S group (P < 0.05). In addition, Ruminococcus spp., especially Ruminococcus albus were the predominant bacterial species found in both S and Z groups. The proportion of Coprococcus spp. significantly increased in Z group (P < 0.05). These findings suggested that the antibiotics used may cause significant changes in the caecum microbiota of rex rabbits, and we also found C group had a similarity caecum bacteria structure with B group which was probably due to the high levels of chlortetracycline resistance.
RESUMEN
Yupingfeng (YPF) is a kind of Astragali radix-based ancient Chinese herbal supplemented with Atractylodis Macrocephalae Rhizoma and Radix Saposhnikoviae. Increasing evidence has proven the beneficial immunomodulating activity of YPF. However, the action mechanism(s) of it is not known. Here, we explored the immunomodulatory activity of unfermented Yupingfeng polysaccharides (UYP) and fermented Yupingfeng polysaccharides (FYP) obtained using Rhizopus oligosporus SH in weaning Rex rabbits. The results showed that both UYP and FYP exhibited notable growth-promoting and immune-enhancing activities, improvement of the intestinal flora homeostasis, and maintenance of intestinal barrier integrity and functionality. Notably, compared with UYP, FYP effectively enhanced average daily gain, organ indices, interleukin-2 (IL-2), IL-4, IL-10, tumor necrosis factor-alpha (TNF-α), TLR2, and TLR4 mRNA levels in spleen, IL-1, IL-2, IL-4, IL-6, IL-10, IL-12, TNF-α, and IFN-γ protein concentrations in serum, and TLR2 and TLR4 mRNA expressions in the gastrointestinal tract (GIT). Moreover, FYP exhibited greater beneficial effects in improving the intestinal flora, including augment flora diversity and the abundance of cellulolytic bacteria, reduction the abundance of Streptococcus spp. and Enterococcus spp. in the GIT, particularly the foregut and maintaining the intestinal barrier integrity and functionality by upregulating zonula occludens 1, claudin, polymeric immunoglobulin receptor, trefoil factor, and epidermal growth factor mRNA levels in the jejunum and ileum. Our results indicated the immunoenhancement effect of FYP is superior over that of UYP, which is probably related with the amelioration of the intestinal microflora and intestinal barrier in the foregut.