Effects Of Astragalus Membranaceus On Growth Performance, Immune Performance And Antioxidant Status In Broilers

This study was divided into two experiments to research effects of different additive level and particle size of astragalus membranaceus root powder on grow performance of broiler chicken and influential mechanism.The first experiment was designed to study the effects of different astragalus additive amount on grow performance, immunity property and antioxidant status of broiler chicken. A total of 720 broilers were chosen and assigned randomly to six treatments with three replicatesof 40 broilers. The six dietary treatments included a control that was a corn-soybean meal basal diet, basal diet supplemented with 48 mg/kg antibiotic, 350 mg/kg astragalus polysaccharides (APS), or 0.5 %, 1.0 % or 1.5 % astragalus membranaceus root powser.At 21 d old, the results demonstrated that the broilers fed astragalus powder had similar ADG, feed intake and F/G to birds in other dietary treatments (P >0.05). Birds fed APS had higher abdominal fat yield than birds in control treatment (P <0.05). The index of bursa of fabricius of birds in 0.5 %, 1.5 % astragalus powder groups and antibilitic group were significantly higher than that of birds in APS group (P <0.05). The quantities of GRAN in blood of broilers fed basic diet supplemented with 1.5 % astragalus powder were significantly higher than that of broilers fed basic diet, APS and the 0.5 % astragalus powder (P <0.05). The liver T-AOC of birds fed 1.0 % astragalus powder were significantly higher than the birds fed basic diet, APS and 0.5 % astragalus powder (P<0.05). The serum SOD activity of birds was increased by 23.38 % by 1.5 % astragalus powder compared with 0.5 % astragalus powder group (P <0.05). At 42 d old, ADFI of birds were increased by 1.0 % astragalus powder by 5.71 % compard with APS (P < 0.05). The ADG was increased by 8.06 % and by 7.04 % by 1.0 % astragalus powder compared with basic diet and APS (P < 0.05). 1.0 % astragalud powder reduced F/G by 3.77 % compared with basic diet (P < 0.05). EE of nutrient real metabolic rate of broilers in treatment groups of 1.0 % astragalus powder and APS group were increase by 8.19 % and 7.30 % compared with birds in control group (P <0.05). The BMY and LMY of birds in the 0.5 % astragalus powder group were increased by 11.40 %, 9.63 % than birds antibiotic (P < 0.05) and LMY was increased by 11.36% than birds in 1.5 % astragalus powder group (P < 0.05). The L* of broilers in the APS group was significantly higher by 5.64% than that in 0.5 % astragalus powder group (P <0.05). The b* in the APS group and 0.5 % astragalus powder group was higher by 15.97 % and 17.88 % than the control group (P <0.05). The b* in 0.5 % astragalus powder group was increased by 15.16 % than that in 0.5 % APS group (P <0.05). The index of bursa of fabricius of birds in 1.0 % astragalus powder group was increased by 36 % than basic diet (P <0.05). The activities of GSH-PX in the liver of broilers fed 0.5 % and 1.0 % astragalus powder was increased by 31.29 % and 35.89 % compared with basic diet (P <0.05). The serum T-AOC of birds fed 1.0 % astragalus powder was significantly higher than that of birds fed basic diet, antibiltic and 0.5 % astragalus powder (P <0.05). The serum GSH-Px of birds fed 1.0 % astragalus powder was significantly higher than the control group, antibiltic group and the 0.5 % astragalus powder group (P <0.05). The serum MDA of broilers in the control group was significantly higher than the polysaccharides group and the 0.5 %, 1.0 %, 1.5 % astragalus powder group (P <0.05).The second experiment was designed to study the effects of different astragalus powder particle size on grow performance and antioxidant status of broiler chicken. A total of 120 broilers were chosen randomly to distribute into five treatments with four replicates of 6 birds. Broilers in control group (Group A) were fed the basic diet. The experimental dietwere tha basic diet added with astragalus powder (B: 300um, C: 149um, D: 74um, E: 37um).Different particle size astragalus powder at the level of 0.5 % had no effect on grow performance of birds (P >0.05).At 21 d old, the activities of SOD and GSH-PX were significantly improved by different particle size astragalus powder (P <0.05). The results showed that as the particle size diminishing, the serum SOD and GSH-PX activities were improved. They had a linearly relation.At 42 d old, the activities of SOD and GSH-PX in the experiment groups was higher than the control group (P <0.05). Birds fed astragalus powder whose particle was 300μm had highest GSH-PX activity that was higher significantly than control group and 74μm group (P < 0.05). In the whole test, the content of MDA was decreased by any particle size astragalus powder (P <0.05). And as the particle size diminishing, the serum MDA was decreased. They had a linearly relation.It was concluded that astragalus powder could improved the growth performance, meat yield performance, immunity property and antixitant status. The optimal levels used in the broilers diet were 1.0 %. And broilers had the better antioxidant status as the particle size diminishing.