Inflammatory response is a complex physiological response of the immune system to external stimuli, which is regulated by a variety of inflammatory mediators. Appropriate amount of inflammatory factors plays an important role in maintaining the normal physiological functions of animals, but when animals are infected by viruses or bacteria, a large amount of inflammatory factors will be deposited in the body, leading to serious inflammatory damage (13–15). Atractylenolide I and atractylenolide III can reduce the expression level of tumor necrosis factor-α (TNF-α) and the production of nitric oxide (NO) in animal serum. Atractylenolide I showed a more effective inhibitory effect on the production of TNF-α and NO in peritoneal macrophages activated by lipopolysaccharide (LPS) than atractylenolide III (16). Both nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways can regulate the release of inflammatory factors in animals. The study by Jeong et al. (17) showed that atractylenolide I and Atractylenolide III could inhibit the phosphorylation of p38 MAPK, c-Jun N-terminal kinase (JNK), and inhibitor of nuclear factor-κB (IκB) in LPS induced mouse inflammatory macrophages, promote the phosphorylation of extracellular signal-regulated kinase (ERK), block the translocation of NF-κB to the nucleus, and significantly reduce the expression of pro-inflammatory factors such as TNF-α, interleukin-6 (IL-6), and interleukin-1β (IL-1β). In addition, atractylenolide II can reduce the release of inflammatory factors such as NO, TNF-α, and IL-6 in mouse macrophages induced by LPS, but the effect is not significant (18). In summary, atractylenolide, as the most effective anti-inflammatory component in Atractylodes lancea, can reduce the expression level of inflammatory factors and alleviate inflammatory damage by regulating the MAPK and NF-κB signaling pathways, but the inflammatory regulation mechanism of other compounds still needs further study.

Reactive oxygen species (ROS) are extremely bio-active materials. Excessive levels of ROS in livestock and poultry can cause oxidative stress (19). The phenolic acids and flavonoids contained in Atractylodes lancea have metal chelating and free radical scavenging functions, inhibiting the production of ROS (20). The Nrf2-Keap1 signaling pathway plays a pivotal role in the antioxidant response of animals and increase the activity of antioxidant enzymes, among which Nrf2 is the main effector (21). Study had shown that Atractylodes polysaccharide II can increase the activity of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in the tissue of mouse liver, significantly reduce the activity of nitric oxide synthase (NOS) and the content of NO and malondialdehyde (MDA) (22). It can be seen that A. lancea polysaccharide has good antioxidant activity. On the one hand, A. lancea polysaccharide balances the antioxidant system in animals by inhibiting the production of ROS; On the other hand, A. lancea polysaccharide can regulate the Nrf2-Keap1 signaling pathway, enhance the activity of antioxidant enzymes SOD and GSH-Px, and improve the ability of animals to clear ROS.

Viral infections such as swine flu and avian flu are extremely harmful to livestock and poultry production. The clinical manifestations include diarrhea, cough, fever, and lameness. Mild cases can cause breathing and movement difficulties, while severe cases can lead to large-scale deaths, seriously affecting the economic benefits of the breeding industry. A. lancea can act on the cell surface to change the protein receptor structure, significantly block the adsorption and penetration of swine influenza virus into cells. Study has shown that A. lancea can significantly inhibit the proliferation of swine influenza virus in cells and has a direct effect of inactivating virus (23, 24). In addition, atractylone, as the main antiviral ingredient in A. lancea, can block the adsorption and replication of avian influenza virus (25). Toll-like receptor 7 (TLR7) is widely present in immune cells, epithelial cells and nerve cells. When livestock and poultry are invaded by pathogens, TLR7 will immediately transfer to the cell membrane, identify the pathogens, aggregate specific proteins to activate regulatory factors such as IκB, MAPK and interferon (IFN), initiate specific immune responses, and participate in the antiviral process. Atractylone can regulate TLR7 receptors, inhibit the activation of MAPK and NF-κB signaling pathways, relieve epidemic diarrhea and respiratory diseases caused by influenza A virus infection. Chen et al. (26) found that continuous treatment with 10, 20, and 40 mg/kg atractylone for 5 days could alleviate influenza A virus-induced lung injury in mice, significantly reduce serum TNF-α, IL-6, and IL-1β levels, meanwhile increase IFN-β levels, indicating that atractylone can promote IFN-β production by activating the TLR7 signaling pathway, interfere with viral replication, and recruit immune cells to activate specific immune responses and eliminate viruses. Therefore, A. lancea has important application potential in livestock and poultry production because of its antiviral effects.

A. lancea also has anti-tumor, liver protection, diuretic, glucose metabolism, and lipid metabolism regulating functions. Studies have shown that A. lancea polysaccharides have anti-tumor effects, which can activate macrophages through the Toll-like receptor 4 (TLR4) signaling pathway, reduce the expression of B cell lymphoma-2 (Bcl-2), increase the expression of pro-apoptotic factors such as Bcl-2-associated X protein (Bax) and cysteine aspartate proteinase-9 (Caspas-9), finally promote tumor cell apoptosis (27–29). Additionally, A. lancea polysaccharides can prevent liver damage caused by harmful chemicals and toxins. Han et al. (22) showed that A. lancea polysaccharide can reduce the expression levels of AST, ALT, and MDA in liver, increase the activity of SOD and GSH-Px, and alleviate LPS-induced liver inflammation in mice by inhibiting the NF-κB signaling pathway. It is reported that A. lancea has a diuretic effect. Study has found that intravenous injection or oral administration of 1.0 g/kg A. lancea solution can significantly increase the urine output of mice (27). In addition, the active ingredients in A. lancea can improve glucose uptake, inhibit fat production, and regulate lipid metabolism in animals (30). The regulatory mechanism of A. lancea on MAPK, NF-κB, Toll-like receptor (TLR) and Nrf2-Keap1 signaling pathways is shown in Figure 2. The key functions and associated mechanisms of Atractylodes lancea was showed in Table 1.

A. lancea is rich in natural active substances, which have multiple functions such as improving immunity, resisting stress and promoting digestion. It has great potential in improving the production performance of livestock and poultry. Li et al. (31) found that adding 3, 6, and 9 g/kg of A. lancea polysaccharide to the diet could significantly improve the growth performance of early weaned piglets. On the one hand, A. lancea polysaccharides can play an antioxidant role and alleviate the adverse effects of stress on growth performance (32). On the other hand, A. lancea polysaccharide can stimulate lymphocyte proliferation and antibody production in early weaned piglets, improve disease resistance and reduce diarrhea rate (33). In addition, A. lancea also plays an important role in improving the productive performance of poultry and ruminants. Study has found that adding A. lancea polysaccharides to laying hen diets can significantly increase egg weight, egg production rate, and feed conversion rate, reduce mortality of laying hens (34). In the ruminants, studies have shown that adding 0.75% of A. lancea to the diet can improve the fermentation capacity, increase the efficiency of rumen microorganisms in degrading substances such as protein and cellulose, and promote the synthesis of bacterial protein in the rumen (35). It can be seen that A. lancea has good application value and research potential in improving the production performance of livestock and poultry, but its specific addition amount needs further exploration.

After weaning, piglets lose the protection of maternal antibodies and their immune system is not fully developed, so they are easy to meet with problems such as poor disease resistance, growth retardation and diarrhea. Li et al. (36) added 0.3% purified A.lancea polysaccharide, 0.6% crude polysaccharide and 0.6% crude A. lancea polysaccharide to the diet of weaned piglets. The results showed that all three polysaccharides could increase the antibody content in serum, promote lymphocyte proliferation and improve immunity of weaned piglets. Wang et al. (37) found that adding 0.1, 0.2, and 0.3% fermented A. lancea to the diet of early weaned piglets could increase the levels of immunoglobulin A (IgA), immunoglobulin G (IgG) and immunoglobulin M (IgM) as well as TP and ALB in the serum, among which 0.2% fermented A. lancea had the most significant effect. Interleukin-1(IL-1) and interleukin-2 (IL-2) are cytokines produced by activated T cells, which can stimulate the proliferation and differentiation of immune cells and enhance animal immunity. The experimental results of Xu et al. (33) showed that adding an appropriate amount of A. lancea polysaccharide to the diet of weaned piglets can promote lymphocyte proliferation, increase the levels of antibodies such as IgA and IgG in serum and release cytokines such as IL-1 and IL-2, thereby improving the immunity of weaned piglets. A. lancea can significantly increase the spleen and thymus index of livestock and poultry, and it has a positive effect on improving immunity and intestinal health. Li et al. (38) found that A. lancea polysaccharide can alleviate cyclophosphamide-induced immune organ damage in geese. In ruminants, A. lancea polysaccharides can induce the proliferation of bovine mammary lymphocytes and activate immune cells (39). In summary, A. lancea can be used as an immunomodulator and has important application potential in livestock and poultry production, but its specific mechanism of regulating immunity needs further study.

Heat stress refers to the sum of non-specific physiological responses made by the body to any requirements imposed by the thermal environment at high ambient temperatures (52). In general, there is an isothermal zone in homeothermic animals, and when the ambient temperature is in the range of the isothermal zone, the animal can maintain normal temperature through body temperature regulation; When the ambient temperature is higher than the upper limit of the isothermal zone, the animal will be subjected to heat stress (64). When heat stress occurs, animals typically show increased breathing, increased heart rate, and impaired electrolyte balance (53). Therefore, heat stress can effect the growth performance and reproductive performance. Under the influence of heat stress, animals' appetite decreases, resulting in a decrease in feed intake, which seriously affects production performance (54). Studies have shown that heat stress can lead to oxidative stress, adding A. lancea to pig diets can increase the activity of antioxidant enzymes in serum, reduce MDA and ROS levels, and thus alleviate heat stress (55, 56). A. lancea can terminate lipid peroxidation by removing ROS and hydrogen peroxide, improve ROS-induced intestinal epithelial cell shedding, and restore the digestive and absorptive functions of the intestine. Xu et al. found that adding A. lancea polysaccharides to broiler diets can significantly improve the antioxidant capacity, enhance immunity, and alleviate the damage caused by heat stress (57). In addition, A. lancea also has a good effect in alleviating heat stress in ruminants. It has been reported that under heat stress conditions, adding A. lancea to cattle diets can significantly improve immunity and antioxidant capacity, promote rumen digestion and absorption of nutrients in the feed, and improve production performance (57). It can be seen that A. lancea plays an important role in alleviating heat stress in animals, but its effective components and optimal additive dosage need further study.