The role of Astragalus membranaceus as immunomodulator in poultry

Astragalus membranaceus (AM) is a member of the family Leguminosae which has been widely used as immunomodulatory agent. Astragalus polysaccharides (APS) possess promising biological activities like immune enhancing, anti-oxidant, antiviral, anti-microbial and anti-parasitic activities. Researchers have studied the immune enhancing activities of AM in birds and reported that APS and sulphated APS (4 or 8 mg/kg of body weight) showed immunomodulatory effects broiler chicks infected with lipopolysaccharide and modulated the resulting negative effects. AM powder supplementation in broiler feed at levels of 0, 100, 200 and 300 mg /kg diet increased the immune organs weight and IgG level and improved the liver and kidney functions and antioxidant status. Dietary APS (10 g/kg) promoted the growth rate and the histology of jejunum of offspring chickens. The addition of crude AM at 0.5% in laying hen feed for 21 days was able to improve the composition of faecal microorganisms. The following review describes the structure and chemical composition of AM and its immunomodulatory role in improving the health status of poultry and its mechanisms of action.