| Astragalus membranaceus,also known as Astragalus mongholicus var.mongolicus(Bunge)P.K.Hsiao or Astragalus mongholicus,has a long history of medicinal use.Its main active ingredients include polysaccharides,saponins,flavonoids,and amino acids,trace elements,etc.Adding compound Chinese herbal medicine to animal feed can enhance animal immunity and improve antioxidant capacity,Huangqi is often used as an important medicinal herb in additives.Research has shown that the aboveground parts of Astragalus membranaceus also contain a large amount of medicinal active ingredients.In this experiment,2-year-old Mongolian Astragalus membranaceus was used as the material.Astragalus membranaceus was harvested during the pregnancy stage,flowering stage,and podding stage,and its agronomic and hay nutritional indicators were measured.The stems and leaves of Astragalus membranaceus were made into semi dry silage,and the nutritional and silage indicators of the silage were measured.Samples of the underground part,pre silage stems and leaves,and post silage stems and leaves during the podding stage were selected for a wide target analysis of metabolites,Using analytical data to provide theoretical basis for the practical application of astragalus silage,the main results are as follows:(1)Different cutting periods had a certain impact on the agronomic indexes of astragalus,the average height and fresh weight of astragalus at the peak flowering stage were the highest,165.86 cm and 123.86 g,respectively,the lowest stem-to-leaf ratio of astragalus in the pregnant bud stage was 2.69,the highest stem-to-leaf ratio of astragalus in the pod stage was 4.56,the fresh-dry ratio of astragalus in the pregnancy stage was 3.57,and the lowest fresh-dry ratio of astragalus in the pod stage was 2.95.The highest yield of astragalus stems and leaves at full flowering was1178.82kg/mu,and the overall trend of fresh root weight and root yield per plant showed an upward trend with the progress of the cutting period,but it did not reach the significant difference level.(2)The stems and leaves of biennial Mongolian astragalus have high nutritional value as forage,among which the forage quality of forage in the gestational stage is the highest,according to the quality classification of national legume forage hay,25.47% of acid detergent fiber reaches the special level,44.60 of neutral detergent fiber reaches the first level,and the crude protein content reaches the tertiary level,and its relative feed value is 186.98.(3)The semi dry silage of two-year Mongolian Astragalus membranaceus stems and leaves has a good effect.According to the sensory evaluation standard of the German Agricultural Association(Deutche Landwirtschafts Geseutschaft)for silage quality,the sensory quality of the silage during the three cutting periods has reached the first level.In terms of nutritional quality,the lowest content of acidic washing fiber and neutral washing fiber during the embryonic stage is39.13%,50.73%,and the highest content of crude protein is 12.81%,The highest content of acidic washing fiber and neutral washing fiber during the podding stage is 39.90%,60.4%,and the lowest content of crude protein is 9.71;The crude fat content of Astragalus silage during the three cutting periods did not reach a significant difference level,while the crude ash content was all 12.5%lower than the maximum limit indicator;In terms of fermentation quality,the lowest ammonia nitrogen/total nitrogen during the embryonic stage is 3.4%,indicating a low degree of protein decomposition and good silage quality.Other indicators did not show significant differences.(4)This experiment compared the differences in metabolites of Astragalus membranaceus roots,Astragalus membranaceus stems and leaves,and Astragalus membranaceus stems and leaves after silage through wide target analysis.Firstly,differential metabolite pathway analysis was conducted.The differential metabolites between Astragalus membranaceus stems and leaves and Astragalus membranaceus roots were significantly enriched in the flavonoid metabolism pathway,and there were more flavonoid substances in Astragalus membranaceus stems and leaves;The differential metabolites of Astragalus membranaceus after silage and before silage were significantly enriched in the flavonoid metabolism pathway,purine metabolism pathway,and phenylpropanoid biosynthesis pathway.The results showed that the trend of metabolite changes in Astragalus membranaceus during silage was similar to that during stress response.(5)162 substances involved in the flavonoid metabolism pathway,terpenoids,and polyketone compounds metabolism pathway were selected from 556 metabolites detected through wide target detection for comparison.It was found that in the comparison of 162 metabolites between the stem and leaves of Astragalus membranaceus and the root,a total of 29 were upregulated,and 13 were downregulated,indicating that the secondary metabolic activity of the stem and leaves of Astragalus membranaceus was more active than that of the root;In comparison with 162 metabolites before and after silage,a total of 21 metabolites were up-regulated and 18 metabolites were down-regulated,indicating that secondary metabolic activities may have occurred during the silage process of Astragalus membranaceus.Screening out 16 types of Astragalus membranaceus with higher content of active substances with medicinal effects(including Astragaloside IV and Physalis isoflavones),conducting multiple analysis of differences,it was found that the content of active substances in the stems and leaves of Astragalus membranaceus was higher than that in the roots of Astragalus membranaceus,but the content of Astragaloside IV,Physalis isoflavones,and Rhodiolin was lower than that in the roots of Astragalus membranaceus;In the comparison of 16 active substances in the stems and leaves of Astragalus membranaceus before and after silage,it was found that a total of 9 metabolites reached significant levels of difference,of which 5 were up-regulated and 4 were down-regulated.Among them,there was no significant difference in the levels of flavonoids in the hairy stamen and astragaloside IV,indicating that semi dry silage did not have a significant negative impact on the medicinal active ingredients of Astragalus membranaceus. |
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