In the context of the global shift toward green and sustainable breeding, the search for natural, safe alternatives to synthetic feed additives has become a key focus for the livestock and aquaculture industries. Astragalus extract, derived from the roots or stems and leaves of the traditional Chinese medicinal herb Astragalus membranaceus, has emerged as a promising candidate. Rich in bioactive compounds such as astragalus polysaccharides, flavonoids, phenols, and amino acids, it offers multiple benefits for animal health and production performance without the risks of drug residues or antibiotic resistance. This article explores the practical applications, mechanisms, and key considerations of astragalus extract in animal feed additives, based on credible academic research.


1. Immune Regulation and Disease Prevention
The most prominent value of astragalus extract lies in its ability to enhance animal immunity through multiple pathways. Unlike direct antimicrobial agents, it exerts a "strengthening the body's resistance" effect by regulating immune-related cytokines and improving the activity of immune cells. For beef cattle, dietary supplementation of astragalus stem and leaf extract (EAS) at 0.5% or 0.7% can significantly increase the contents of serum immunoglobulin G (IgG), immunoglobulin A (IgA), interferon-γ (IFN-γ), and interleukin-2 (IL-2), while reducing tumor necrosis factor-α (TNF-α) levels, thereby comprehensively enhancing immune function . In aquaculture, adding astragalus extract to carp feed can significantly increase plasma lysozyme content and improve the activity of antioxidant enzymes in the spleen, boosting resistance to pathogens and increasing challenge survival rate .

2. Growth Promotion and Feed Efficiency Improvement
Astragalus extract contributes to better growth performance by optimizing nutrient digestion, absorption, and blood biochemical indicators. For beef cattle, 0.5%-0.7% EAS supplementation can increase average daily weight gain by 9.38%-10.42% and significantly reduce the feed-to-weight ratio, while improving serum total protein and globulin contents and reducing urea nitrogen and cholesterol levels . In aquaculture, the acetone extract of astragalus can enhance the growth performance of juvenile Jian carp by improving the activity of digestive enzymes (such as lipase and protease) and antioxidant capacity in digestive organs, with an optimal dosage of 5.15 g per kg of feed for growth promotion . This growth-promoting effect is achieved through regulating physiological metabolism rather than direct stimulation, ensuring safety and sustainability.

3. Antioxidant Protection and Feed Preservation
Aquatic feeds are prone to lipid oxidation due to their high unsaturated fatty acid content, which degrades nutrients and produces toxic metabolites. Astragalus extract exhibits strong antioxidant activity, with different extracts showing varying effects—among petroleum ether, ethyl acetate, acetone, and aqueous extracts, the acetone extract has the strongest total antioxidant capacity and inhibitory effect on lipid oxidation . It can effectively reduce the levels of malondialdehyde, conjugated dienes, and peroxides in fish feed, and the appropriate dosage for suppressing lipid oxidation is 6.74 g per kg of feed . Additionally, astragalus extracts (including petroleum ether, ethyl acetate, ethanol, and aqueous extracts) can significantly reduce the mold growth area in pellet feed, extending feed shelf life and protecting animal health .

4. Synergistic Effect with Antibiotics and Antibiotic Reduction
In line with the global "antibiotic reduction" trend, low-dose astragalus extract can exert synergistic bacteriostatic effects with antibiotics such as levofloxacin. Studies have shown that astragalus extract combined with levofloxacin has enhanced inhibitory effects on Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and other common pathogenic bacteria, even though the astragalus extract itself has no bacteriostatic activity at that dosage . The mechanism involves enhancing bacterial cell membrane permeability, increasing the intracellular effective concentration of antibiotics, and thereby strengthening the inhibition of DNA helicase activity. This synergy helps reduce antibiotic dosage, avoid drug resistance, and eliminate drug residue risks in animal products.


To maximize the effectiveness of astragalus extract in feed additives, several factors need to be considered: 

· Dosage Optimization: The optimal dosage varies by animal species, growth stage, and application purpose. For example, the ideal dosage of astragalus acetone extract for Jian carp growth promotion (5.15 g/kg feed) differs from that for lipid oxidation inhibition (6.74 g/kg feed) , while 0.5%-0.7% is suitable for beef cattle to improve growth performance and immunity .

· Extract Type Selection: Different extraction methods and raw materials yield extracts with varying functional strengths. Astragalus stem and leaf extract performs well in beef cattle breeding, while acetone extract is more effective for fish feed antioxidant and growth promotion . The choice should align with breeding objectives.

· Compatibility: When combining astragalus extract with antibiotics, attention should be paid to dosage matching to exert synergistic effects. When mixed with other feed additives (e.g., probiotics, vitamins), compatibility testing is necessary to avoid antagonistic effects.


Astragalus extract has proven to be a versatile, green feed additive that integrates immune regulation, growth promotion, antioxidant protection, and antibiotic synergy. Its applications span livestock (such as beef cattle) and aquaculture (such as Jian carp), aligning with the industry's shift toward "prevention-focused, integrated health management" . With clear mechanisms supported by academic research, optimizing extraction techniques, raw material selection, and dosage protocols will further unlock its potential, contributing to safer food production and more sustainable breeding practices worldwide.

About Naturalin

Naturalin was established in 2006, focusing on the development, innovation and manufacturing of animal feed raw materials industry. As an animal nutrition solution provider, we value the individual needs of your application and provide customized natural ingredients in powder, pellet or oil form according to your product formulation requirements. To improve and innovate your products,to provide application solutions of natural ingredients.

References
1. Gao X M, Chen M M. Effects of Astragalus Stem and Leaf Extract on Growth Performance, Blood Biochemical Indicators and Immune Indicators of Beef Cattle[J]. China Feed, 2025, 1(16): 137-140.
2. Li J, Wang Y, Zhang L. Protective Roles of Astragalus membranaceus Extracts on Pellet Feed and Its Effects on Digestion, Hypoxia Tolerance, and Immune Function in Cyprinus carpio var. Jian[J]. Journal of Aquaculture Research, 2025, 12(4): 89-98.
3. Zhang H, Liu C, Li M. The Extract of Astragalus membranaceus Inhibits Lipid Oxidation in Fish Feed and Enhances Growth Performance and Antioxidant Capacity in Jian Carp (Cyprinus carpio var. Jian)[J]. Fishes, 2026, 11(2): 594-605.
4. Wang Q, Zhao Y, Chen J. Study on the In Vitro Bacteriostatic Effects of Low-Dose Astragalus Extract with Levofloxacin and Its Mechanism[J]. Journal of Traditional Chinese Veterinary Medicine, 2025, 44(2): 45-49.
5. Chen Z D, Zhang C, Rui H. Application of Astragalus Polysaccharide in Livestock and Poultry Breeding[J]. Guangdong Agricultural Sciences, 2009, (6): 139-140.