Study On The Mechanism Of Improvement Of Production Potential And Nutrient Quality Of Alfalfa/Gramineae Grasses Intercropping And The Utilization Effect Of Livestock

Intercropping has been widely concerned in agricultural production because of its characteristics of efficient and sustainable use of agricultural resources and ensuring the productivity and stability of agro-ecosystem.At the same time,leguminosae/gramineae intercropping not only has the above advantages,but also helps to realize the simultaneous nutrient balance of leguminosae and gramineae grass mixed silage?wrapped silage,cellar storage?.For this reason,three years of field trials were carried out in 2017,2018 and 2019 in Henan Xinxiang area.Four intercropping patterns of alfalfa?Medicago sativa?/triticale?Secale sylvestre?,alfalfa/oat?Avena sativa?,alfalfa/maize?Zea mays?and alfalfa/sorgo?Sorghum dochna?were studied.The leguminosae/gramineae row ratio of the patterns are the best ratio which has been proved to have good production performance,and the quality of forage grass in mixed harvest products is close to the optimal proportion of mixed silage).In view of the whole industrial chain,such as forage intercropping pattern,cultivation management,production and processing and transformation and utilization of livestock,Firstly,the production benefit,economic benefit and ecological benefit of alfalfa/gramineous intercropping forage,and the main factors of yield formation in many factors of light energy utilization,as well as the difference and mechanism of net photosynthetic rate between alfalfa and gramineous forage under monocropping and intercropping were discussed.At the same time,the root characteristics and soil microecological effects of alfalfa/gramineae intercropping were also studied.Then,the nutritional quality,fermentation quality,sensory quality and the change of fiber microstructure based on scanning electron microscope were evaluated.Finally,the feeding effect and simulated digestion experiment of ruminant were carried out by using the mixed silage products of alfalfa/gramineae intercropping forage,and the effects of silage on the utilization characteristics of grass were studied by studying the microstructure changes of forage fiber in different processing methods through the scanning electron microscope technique.The results of the study are as follows:1.The mechanism of improving the productive potential of alfalfa/gramineous forage intercroppingIn terms of production performance,the forage intercropping pattern showed that the gramineous forage had the advantage of intercropping yield,while alfalfa showed the disadvantage of intercropping yield.The results were consistent with the performance of interspecific competitiveness,which indicated that the four species of gramineous grasses were more invasive in the utilization of intercropping system resources,and their productivity was the main factor determining the overall yield.Among the intercropping patterns,the biological yield of alfalfa/sorgo intercropping pattern was the highest,and the land use efficiency of alfalfa/triticale and alfalfa/oat intercropping patterns were the highest.In terms of economic benefits,alfalfa/triticale intercropping pattern has higher pure profit,income-cost ratio and monetary advantage index.In terms of light energy utilization,compared with monocropping,intercropping increased the light energy utilization efficiency,leaf area index,net photosynthetic rate,stomatal conductance,transpiration rate and PAR interception rate.The canopy opening and intercellular CO₂ concentration decreased,while alfalfa showed the opposite trend.Among the intercropping patterns,the light energy utilization potential of alfalfa/triticale and alfalfa/oat was greater.From the difference of net photosynthetic rate between monocropping and intercropping and its mechanism,the increase of net photosynthetic rate of intercropping gramineous forage under strong light was realized by enhancing the carboxylation fixation ability of CO₂.It is not the improvement of the efficiency of light energy capture,transmission and conversion.The decrease of net photosynthetic rate of intercropping alfalfa under strong light was caused by the decrease of carboxylation fixation ability of CO₂.The increase of net photosynthetic rate under weak light was caused by increasing the content of chlorophyll b in its functional leaves,changing the composition of chlorophyll,and enhancing the absorption and transmission of light energy.In terms of metabolic characteristics,the average daily stem flow rate,activities of key enzymes of carbon and nitrogen metabolism and their substance contents of four kinds of gramineous forages under intercropping were higher than those of mono cropping,while alfalfa showed the opposite trend.The average increase of above indexes of triticale and oat was higher than that of maize and sorgo,and the average decrease of alfalfa intercropping with triticale and oat was less than that with maize and sorgo.It can be seen that the two intercropping patterns of alfalfa/triticale and alfalfa/oat have the best metabolic characteristics.According to the root characteristics,the root parameters such as root length and root surface area of gramineae forage were obviously optimized under the four intercropping patterns,but the root characteristics of alfalfa were different from those of monocropping.The root characteristics of alfalfa intercropped with maize and sorgo were significantly inhibited?significantly lower than that of monocropping?,while the root characteristics of alfalfa intercropping with triticale and oat were not affected.On the whole,the root characteristics of alfalfa/triticale and alfalfa/oat intercropping patterns had better performance among the four intercropping patterns.From the effect of intercropping on soil characteristics,intercropping effectively improved the physical and chemical properties and biological properties of soil.The main results were as follows:compared with the monocropping of gramineae,the contents of soil nutrients,especially the available nutrients?available nitrogen,available phosphorus and available potassium?,were significantly increased under the four intercropping patterns.In the third year of intercropping,the content of 3¹ mm aggregate in soil increased significantly,and content of<0.25 mm decreased significantly.Under intercropping,the number of bacteria and actinomycetes increased,the number of fungi decreased,and the ratio of bacteria to fungi increased.In addition,the microstructure of soil was observed by scanning electron microscope technology.The results showed that the agglomeration degree of intercropping soil aggregate was higher than that of gramineous monocropping soil in the third year of planting.The pores on the soil surface were more and looser,and the larger particle size aggregates were more,indicating that the soil structure had been improved to a certain extent under intercropping.2.Effects of different processing methods on the nutritional quality of four kinds of intercropping foragesFor hay quality,compared with monocropping,the contents of crude protein and crude fat and relative feed value of alfalfa decreased,while the contents of neutral detergent fiber,acid detergent fiber and crude ash increased,but the difference was not significant?P>0.05?.Under intercropping,the contents of crude protein and crude fat and relative feeding value of four kinds of grasses increased,while the contents of neutral detergent fiber,acid detergent fiber and crude ash decreased,but the difference was not significant?P>0.05?.Compared with before and after silage,the nutritional quality of forage after silage mainly showed that the content of crude protein was basically unchanged.The contents of neutral detergent fiber and acid detergent fiber decreased?decrease amplitude was2.67%¹0.14%and 3.29%⁹.83%,respectively?,and the relative feeding value increased?increase amplitude was 5.08%¹7.73%?.The microstructure of leaf fiber of four species of gramineous forage before and after silage was observed by scanning electron microscope technology.The results showed that the arrangement of leaf epidermal cells of four species of gramineous forage after silage was disorderly and the cell boundary was not clear,and the surface structure is rough compared with pre-silage.It can be seen that the fiber structure of the leaves of 4 kinds of grass can be partially degraded after silage.The results of forage mixed silage with four intercropping patterns were as follows:?1?Sensory quality.The four mixed silage treatments were better than alfalfa single silage.Among them,the sensory evaluation of alfalfa+maize and alfalfa+sorgo mixed silage treatments was the best?grade 1 excellent?,followed by alfalfa+triticale and alfalfa+oat mixed silage treatments?grade 2 good??2?Nutritional quality.The nutrient components of the four mixed silage treatments were between gramineous forage single storage and alfalfa single storage,which could form complementary nutrients.Among them,the crude protein content and relative feeding value of alfalfa+triticale and alfalfa+oat mixed silage group were higher,and the content of neutral detergent fiber was lower.The content of soluble carbohydrates in alfalfa+sorgo mixed silage group was significantly higher than that in the other three mixed silage groups?P<0.05?,reaching3.43%.?3?Fermentation quality.The V-Score grades of 4 kinds of mixed silage treatments were good,and the Kaiser grades of 4 kinds of mixed silage treatments were grade 1.It can be seen that the four kinds of mixed silage treatments all reach the standard of good silage.?4?Fiber microstructure.There was no significant difference in the microstructure of leaf fibers among the four gramineous forages after silage.3.Utilization effect of livestock on mixed silage grass under four kinds of intercroppingThe digestion test in vitro was carried out by simulating the rumen digestion environment,and at the end of 24 hours of in vitro digestion,the gas production,methane yield,dry matter degradation rate and acetic acid/propionic acid ratio were as follows:alfalfa+sorgo mixed silage>alfalfa+maize mixed silage>alfalfa+triticale mixed silage>alfalfa+oat mixed silage.The concentration of ammonia nitrogen was as follows:alfalfa+oat mixed silage>alfalfa+triticale mixed silage>alfalfa+maize mixed silage>alfalfa+sorgo mixed silage.The comprehensive indexes obtained by summing up the comprehensive indexes of each single index showed that alfalfa+sorgo mixed silage>alfalfa+maize mixed silage>alfalfa+triticale mixed silage>alfalfa+oat mixed silage.It can be seen that the mixed storage of alfalfa and sorgo has the best digestion effect in vitro.The fiber microstructure of leaves of four grasses before and after digestion was observed by scanning electron microscope technology.The results showed that compared with fresh leaves directly used in rumen fluid digestion,silage leaves used in rumen liquid after digestion,the fiber tissue of leaf epidermis of triticale,oat,maize and sorgo was more degraded by rumen microorganisms,and the cell profile basically disappeared,indicating that the silage grass was more easily digested and utilized by livestock.The feeding effect of direct feeding of four kinds of mixed silage forage on domestic animals was studied.The results showed that compared with the direct feeding of alfalfa single silage,after feeding 4 kinds of mixed silage forage,the feeding time,ruminating time,chewing time and chewing time of each food ball of experimental sheep were shortened in varying degrees,and the average daily feed intake was increased in different degrees.Among them,after feeding alfalfa+sorgo mixed silage,the feeding time,chewing time and chewing time of each food ball were the lowest,and the daily feed intake was the highest,indicating that alfalfa+sorgo mixed silage had the best feeding effect.To sum up,in terms of biological yield,the alfalfa/sorgo intercropping pattern had better production performance.In terms of land use efficiency,alfalfa/triticale and alfalfa/oat intercropping patterns had better production potential.From the point of view of economic benefits,alfalfa/triticale intercropping pattern had higher net profit,income-cost ratio and monetary advantage index.According to the nutritional quality,sensory quality and fermentation quality of silage,as well as the effect of rumen digestion in vitro and the feeding effect of livestock,the mixed forage of alfalfa/sorgo was the most suitable for silage among the four intercropping patterns.