As natural bioactive components, plant-derived polysaccharides have many biological functions, such as anti-inflammatory, antioxidant, anticoccidial, and immunity regulation, and have been widely used in poultry production. In this review paper, firstly, the sources and structures of plant-derived polysaccharides are reviewed; secondly, the effects of plant-derived polysaccharides on the intestinal microbiome, permeability, morphology and immune function of poultry are summarized; thirdly, the potential molecular regulation mechanism of plant-derived polysaccharides on the intestinal barrier function of poultry was preliminarily analyzed. The review paper will bring a basis for the scientific utilization of plant-derived polysaccharides in the poultry industry.

The spleen and small intestines are the primary immune organs that provide important immunity against various diseases. Artemisia ordosica polysaccharide (AOP) could be used as an immunologic enhancer to boost immunity in response to infection. This study was performed to explore the effects of the dietary supplementation of AOP on the growth performance and spleen and small intestine immune function in broilers. A total of 288 AA broilers (1 day old) were randomly assigned into six dietary groups. Each group included six replicates of eight broilers per cage. The broilers were fed with a basal diet supplemented with 0 mg/kg (CON), 50 mg/kg chlortetracycline (CTC), 250, 500, 750, and 1000 mg/kg AOP for 42 d. The results showed that dietary AOP supplementation affected broiler growth performance, with 750 and 1000 mg/kg of AOP being able to significantly improve broiler BWG, and 750 mg/kg of AOP was able to significantly reduce the FCR. The dietary AOP supplementation increased the levels of IgA, IgG, IgM, IL-1β, IL-2, and IL-4 in the spleen and small intestine in a dose-dependent manner (p < 0.05). Meanwhile, we found that AOP can promote the mRNA expression of TLR4/MAPK/NF-κB signaling-pathway-related factors (TLR4, MyD88, P38 MAPK, JNK, NF-κB p50, and IL-1β). In addition, the dietary supplementation of 750 mg/kg AOP provides better immunity in the tissue than the CON group but showed no significant difference from the CTC group. Therefore, AOP has an immunoregulatory action and can modulate the immune function of broilers via the TLR4/ NF-ΚB/MAPK signal pathway. In conclusion, dietary supplementation with 750 mg/kg AOP may be alternatives to antibiotics for enhancing broilers’ health, immunity, and growth performance.

Cold conditions in northern China during winter may reduce sheep growth and affect their health, especially if they are young, unless housing is provided. We allocated 45 two-month-old female lambs to be housed in an enclosed building, a polytunnel, or kept outdoors, for 28 days. The daily weight gain and scalp and ear skin temperature of outdoor lambs were less than those of lambs that were housed in either a house or polytunnel; however, rectal temperature was unaffected by treatment. There was a progressive change in blood composition over time, and by the end of the experiment, outdoor lambs had reduced total antioxidant capacity (T-AOC), catalase (CAT), glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) and increased malondialdehyde compared to those in the house or polytunnel. In relation to immune responses in the lambs’ serum, in the polytunnel, immunoglobulin A (IgA), tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) were higher and immunoglobulin G (IgG) lower compared with the concentrations in lambs that were outdoors. Over the course of the experiment, genes expressing heat shock proteins and antioxidant enzymes increased in lambs in the outdoor treatment, whereas they decreased in lambs in the indoor treatments. It is concluded that although there were no treatment effects on core body temperature, the trends for progressive changes in blood composition and gene expression indicate that the outdoor lambs were not physiologically stable; hence, they should not be kept outdoors in these environmental conditions for long periods.

Artemisia ordosica polysaccharides (AOP) can promote animal growth, improve intestinal morphology, regulate immunity, and enhance antioxidant capacity. To investigate the antioxidant capacity of AOP, three experiments were conducted. (1) Different concentrations of AOP (0, 50, 100, 150, 200, and 250 μg/mL) and 1 µg/mL VA on peripheral blood lymphocytes (PBLs) treated with/without lipopolysaccharides (LPS) were investigated to select the optimum concentration. The results showed that 150 μg/mL AOP had significant antioxidation activity. (2) The PBLs was randomly divided into eight treatments with six replicates, namely CON, AOP, LPS, ML385 (Nrf2 inhibitor), AOP + LPS, AOP + ML385, LPS + ML385 and LPS + ML385 + AOP. The results showed that under a normal condition or stress condition, AOP presented antioxidation activity via upregulating Nrf2/Keap1 pathway-related gene expression. (3) The PBLs was randomly divided into eight treatments with six replicates, namely CON, AOP, LPS, PDTC (NF-κB inhibitor), AOP + LPS, AOP + PDTC, LPS + PDTC and LPS + PDTC + AOP. The results showed that under a normal condition, AOP presented antioxidation activity via increasing TLR4/NF-κB pathway-related gene expression; under a stress condition, AOP alleviated oxidative damage caused by LPS via suppressing TLR4/NF-κB pathway-related gene expression.

The purpose of this research was to investigate the impact of chestnut tannins (CHTs) on nutrient digestibility, nitrogen balance, in situ crude protein (CP) digestibility, protease enzymes, and microbial community composition in sheep. Eighteen 1.5-year-old sheep (43.0 ± 2.0 kg initial BW) fitted with permanent ruminal cannula were selected and randomly divided into three groups, which were fed with CHTs added at 0, 2, and 6%/kg DM. The pre-feeding period lasted for 12 days, and the actual trial period was 18 days. Rumen fluid was collected to assess in situ crude protein (CP) degradability, while rumen digesta was analyzed for total and ruminal proteolytic bacterial populations. Using one-way ANOVA in SAS to analyze data, the results indicated that 2% CHT reduced in situ degradability by 26.23%, while 6% reduced it by 58.01% in the rumen of the sheep. The CP apparent digestibility, nitrogen metabolism, and population of proteolytic bacteria of sheep were decreased in the 6% CHT group (p < 0.05), while the above indices of the 2% CHT group were not affected. Furthermore, CHT supplementation significantly altered the ruminal microbial community structure. Particularly in the 2% CHT group, the relative abundances of Bacteroidota and Prevotella increased. LEfSe analysis revealed that Bacteroidale replaced U29-B03 as the dominant microbiota at 2% CHT. Doses of 2% CHT can be incorporated into sheep diets without impairing digestion. These findings support the inclusion of CHT doses of less than 2% for enhancing protein digestion and increasing the types of beneficial bacteria in the rumen, while doses above 6% should be avoided.

This study was conducted through in vivo and in vitro experiments and aimed to reveal the regulatory effect of water extract of Artemisia annua L. (WEAA) on the antioxidant function of mutton sheep and the underlying mechanism. In the in vivo experiment, 32 Dorper × Han female sheep (3 months old; avg. body weight: 24 ± 0.09 kg) were allocated to four groups (eight lambs/group) and fed a diet containing 0, 500, 1000, and 1500 mg/kg WEAA, respectively. In the in vitro experiments, peripheral blood lymphocytes (PBLs) were cultured with different doses of WEAA (0, 25, 50, 100, 200, 400 µg/mL) to determine the optimal concentration, followed by a 2 × 2 factorial experiment with four treatment groups (six replicates per treatment group): the ML385(−)/WEAA(−) group, the ML385(−)/WEAA(+) group, the ML385(+)/WEAA(−) group, and the ML385(+)/WEAA(+) group. The results showed that WEAA supplementation dose-dependently increased serum, liver and spleen tissue total antioxidant capacity, glutathione peroxidase (GSH-Px), and catalase (CAT) activity while reducing malondialdehyde level (p < 0.05). Moreover, WEAA supplementation significantly upregulated the liver and spleen expression of nuclear factor erythroid 2-related factor 2, superoxide dismutase 2, GSH-Px, CAT and NAD(P)H quinone dehydrogenase 1 (p < 0.05) while significantly downregulating the kelch-like ECH associated protein 1 expression in a dose-dependent manner (p < 0.05), thereby activating the Keap1/Nrf2 pathway with the peak effect observed in the 1000 mg/kg WEAA group. Additionally, supplementation with 100 µg/mL of WEAA had significant antioxidation activity in the culture medium of PBLs. Its action mechanism involved the Keap1/Nrf2 pathway; specifically, WEAA exerted its antioxidant effect by upregulating the gene expression related to the Keap1/Nrf2 pathway. In conclusion, WEAA enhances sheep’s antioxidant capacity by up-regulating Keap1/Nrf2 pathway genes and boosting antioxidant enzyme activity. The results provided experimental support for the potential application of WEAA in intensive mutton sheep farming.