Effects of Litter Addition on Soil Organic Carbon Mineralization in the Degraded Alpine Meadow in the Three-River Headwaters Region北大核心CSCD

To explore the effects of plant community structure changes on soil organic carbon mineralization in the different degraded alpine meadows in the Three-River Headwaters Region, we collected topsoil from different degraded alpine meadows, and then added three kinds of litters from different functional groups (grasses, sedges, and forbs) incubated in the laboratory for 203 days. The results showed that the cumulative mineralization of soil organic carbon first increased and then decreased as the degree of soil degradation increased. Litter addition significantly increased the cumulative mineralization of soil organic carbon of non-degraded, slightly degraded, moderately degraded, and severely degraded meadow by 102.04%, 58.71%, 70.68%, and 181.32%, respectively. However, there was no significant difference among the positive effects of different functional groups. Regression analysis showed that soil organic carbon, total nitrogen, and pH of different degraded alpine meadows could better explain the changes in the cumulative mineralization of soil organic carbon. The cumulative mineralization of soil organic carbon first increased and then decreased with soil organic carbon, total nitrogen and pH increased, while the influence degree and direction were altered by litter addition. In general, the plant community structure changes in the different degraded alpine meadows in the Three-River Headwaters Region significantly influenced soil organic carbon mineralization. © 2019 Authors. All rights reserved.     

Soil Degradation Intensity and Spatial Distribution Characteristics of Alpine Grassland in Qinghai Province北大核心CSCD

The evaluation of alpine grassland soil degradation is helpful to grasp the spatial distribution of alpine grassland degradation, and has great significance to maintain grassland ecological security and ensure regional sustainable development. This study evaluated the soil degradation intensity and spatial distribution of alpine grassland in Qinghai Province based on the Improved Revised Universal Soil Loss Equation, and calculated the evaluation index of soil erosion of Alpine Grassland in Qinghai Province from 2005 to 2014, to evaluate the changing trend of soil erosion of alpine grassland. The results showed that the mildly degraded area of alpine grassland in Qinghai Province was 166925 km2, accounting for 39.5% of the total grassland area; the moderately degraded area was 98729 km2, accounting for 23.4% of the total grassland area; the severely degraded area was 949401 km2, accounting for 22.5% of the total grassland area; the extremely severely degraded area was 61787 km2, accounting for 14.6% of the total grassland area in 2014. The overall intensity of soil erosion was centered on the most intense area and radiated to the surrounding area. The main influencing factors included wind erosion, water erosion, and grazing intensity. In addition, the restoration area of soil erosion of alpine grassland in Qinghai Province from 2005 to 2014 was 258495 km2, accounting for 61.2%, which reflects the remarkable achievements of grassland protection in Qinghai Province in recent years. However, the situation of soil degradation of alpine grassland in the middle east of Qinghai Province is still severe, which should be paid great attention by relevant departments. © 2019 Authors. All rights reserved.     

Study on the Characteristics and Interrelationship of Plant Community and Soil in Degraded Alpine Meadow北大核心CSCD

To explore the changes of vegetation and soil characteristics and their relationships in the alpine meadow at different stages of degradation, the plant biomass, species diversity index, soil nutrient, soil physical and chemical properties were measured by the combination of field sample survey and laboratory analysis. The results showed that vegetation coverage, above ground and below ground biomass decreased from slight to severe degradation, the species diversity index, Shannon-wiener diversity index, Evenness index and Simpson index of vegetation community all showed a decreasing trend, and the soil nutrient and physical and chemical properties tended to deteriorate, the decrease of soil moisture and the increase of soil bulk density led to the decrease of biomass. The interaction and interaction between biomass and soil properties can change plant community composition and soil properties and reduce soil nutrient loss in the moderate degradation stage, improving the stability of plant community structure and increasing the diversity of plant community will be beneficial to the restoration of degraded alpine meadow. This study will help to clarify the degradation pattern of alpine meadow in different degradation stages, and provide a scientific basis and theoretical basis for restoring degraded alpine meadow. © 2019 Authors. All rights reserved.     

Effects of Long-term and Short-term Warming on Arbuscular Mycorrhizal Fungal Community in Alpine Meadow Ecosystem北大核心CSCD

To explore whether the effect of experimental warming on the Arbuscular mycorrhizal (AM) fungal community depends on the duration of treatment, this study measured the response of AM fungal community to long-term (17a) and short-term (3a) warming with Open-top Trade Chambers (OTCs) in alpine meadow ecosystem on the Qinghai-Tibet Plateau, and inferred the main ecological processes that drive the assemblage of AM community. Results showed that long-term warming reduced the AM fungal species richness by 45.7%, while short-term warming reduced it by 80%. The negative effect of long-term warming on AM fungal species richness was mediated by the decrease in root biomass, while the negative effect of short-term warming was mediated by soil nitrogen limitation. In addition, both long-term and short-term warming not only changed the species and phylogenetic composition of AM fungal community, but also led to the transformation of the ecological process from environmental filtration to the neutralization of habitat filtration and competitive exclusion. Our results suggest that the intensity and mechanism of the effect of warming on AM fungal community depend on the duration of treatment. This illustrates that the addition of exogenous nitrogen to promote the growth of plant roots is an effective method to alleviate the negative effects of climate warming on AM fungal diversity in the alpine meadow ecosystem. © 2019 Authors. All rights reserved.     

Screening and Identification of Laccase Fungi in Alpine Meadow北大核心CSCD

Nine strains of fungi that isolated from alpine meadow were used as research objects. The laccase-producing strains were identified by rDNA-ITS method. According to the strains, guaiacol, anthrone, catechol and neighbors were identified. Growth on selective medium of toluidine, o-toluidine, crnaphthol, benzidine, gallic acid as substrate, colony size, size of the color circle produced by laccase-catalyzed redox reaction, and the degree of color depth, the laccase-producing fungus is firstly screened, and the laccase activity is determined by the liquid-producing enzyme fermentation method using ABTS as a substrate for re-screening. The results showed that strain 1. 9 was Uncultured fungus clone. 2. la was Scytalidium, 310b was Marasmius tricolor, 2.1c was Saccharicola, 2. 3a was fungal sp, 2. 4d was Saccharicola. 10a was Marasmiusrotalis, 3. 7c was Alternaria. WB was Verticilliumlongisporum. The screening results showed that except for strain 3. 7c, the other 8 strains basically produced oxidative bands on the culture medium with guaiacol, anthrone, ortho-toluidine and benzidine as substrates, and cultured in gallic acid substrate. No oxidative bands were produced on the culture medium; strains 1. 9, 2. la, 310b, 2. 4d, 10a, 2. lc, and 2. 3a all had laccase activity, and strain 310b had stronger laccase activity than the other strains. © 2019 China Agricultural University. All rights reserved.     

Effects of slope on soil properties and post construction desertification of highway embankments in an Alpine Meadow region北大核心CSCD

This research investigated effect of slope on the performance of highway embankment soil properties post construction, as there is a demand for technical data of this nature to underpin the design of highway revetment work in alpine meadow regions of China. A section of national road G248 in Northwest Sichuan Alpine Grassland, built 10 years ago, was identified as a study site and plots were marked out for sampling on five slope classes: gentle slope, 6°-15° (GS); moderate slope, 16°-25° (MS); steep slope, 26°-35° (SS); very steep slope, 36°-45° (VS); extreme slope, >45° (ES). Undisturbed flat natural grassland >10 m distant from the roadbed was used as the control (CK). Measurements conducted included determination of particle size composition, physical and chemical parameters of the soils, vegetation cover and the proportion of the plot area exhibiting degradation or desertification. The relative reduction rate of organic matter and total nitrogen was also determined, and differences in soil water content and fertilizer retention capacity were assessed. It was anticipated these data would provide a basis for the construction of ecologically sound slope protection structures in alpine regions. It was found that: 1) Increased slope significantly decreased the proportion of clay and silt particles and increased the proportion of coarse sand and small stones (P<0.05). The greater the slope, the greater the soil bulk density and pH value, and the lower the soil water content. 2) Slope facilitated leaching of soil carbon fractions with the leaching intensity of the fractions ranking soil organic matter (SOM)>total carbon (TC)>inorganic carbon (IC)>dissolved organic carbon (DOC). For example, SOM levels were, respectively, 115, 92, 72, 30, 9 and 3 mg·kg−1 for CK, GS, MS, SS, VS, and ES slope classes while DOC levels ranged from 35.4 mg·kg−1 in CK to 9.2 mg·kg−1 in ES. 3) The ranking for the effects of slope on various soil fertility measures was: effective N>alkali-hydrolysable N>total N>available K> available P>total K>total P. Thus, available N was more easily lost than total N and alkali-hydrolysable N. Available N levels declined progressively across slope classes from 236 mg·kg−1 in CK to 6.3 mg·kg−1 in ES, while total N and alkali-hydrolysable N showed marked loss between GS and VS slope classes. A slope threshold for sharp increase in loss of total P and available P was observed between GS and MS slope classes. With increase in slope gradient, the total K increased, while the available K content decreased. 4) With respect to the influence of slope on the degree of desertification: for CK and GS >90% of the plot area was classed as non-desertified; for GS 79% of the plot area was moderately or severely desertified; for SS, VS and ES, 79, 86 and 94%, respectively, of the plot area was severely or extremely severely desertified. The proportion of severe desertification increased markedly at > 15° slope (i. e. MS) and the proportion of extremely severe desertification increased markedly at >25° slope (i. e. SS). 5) When the slope effects were expressed in relative terms, the relative increase in desertification was high and changed little at slopes >15°, while the relative decreases in organic matter and total nitrogen were high and changed little once slope exceeded 25°. As slope angle increased, relatively low rate of total coverage percentage and powder particles <0.02 mm and the relative increase rate of sand particles >0.05 mm increase significantly. In summary, as slope of the study plots increased, fine sand, silt and clay particles were progressively lost, soil fertility progressively declined, and the degree of desertification increased markedly. Therefore, the technical plan for ecologically sound slope protection in highway construction should be formulated according to the steepness of the slope. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Drought Evaluation and Driving Force Analysis of Grassland in Qinghai Province北大核心CSCD

This study was aimed to find out the drought characteristics and driving factors of grassland in Qinghai Province. The grassland coverage area in Qinghai Province was selected as the sampling site. The temporal and spatial distribution characteristics and occurrence trend of grassland drought in Qinghai Province were evaluated according to the water balance and crop water requirement and the key driving factors of drought were explored. The results showed that: during the whole growing season, the grassland in the eastern agricultural area, the peripheral area of the Qinghai Lake and the Qilian mountain area maintained light drought and no drought. The serious drought areas were mainly distributed in the southern Qinghai Pastoral Area and some low coverage grassland areas. The spatial distribution of drought was low coverage grassland > medium coverage grassland > high coverage grassland; the drought disaster type of grassland in the whole growing season was mainly light drought, followed by medium drought, the frequency of severe drought and special drought was low, and the intensity of extreme drought was increasing; precipitation and evapotranspiration played the largest driving role in the whole drought process, and they were all negative. With the aggravation of drought grade, evapotranspiration gradually replaced precipitation as the most important driving factor. On the whole, wind speed has a positive effect on drought, while temperature, sunshine hours, and water vapor pressure have little effect on drought. © 2019 Authors. All rights reserved.     

Effects of Nitrogen Deposition on Soil fungi Community Structure in Stipa Baicalensis Steppe北大核心CSCD

Effects of six continuous years nitrogen deposition on soil fungi community structure in Stipa Baicalensis steppe were investigated by using high-throughput sequencing technology. The experiment included eight manipulative treatments:(0,15,30,50,100,150,200 and 300 kg N·hm-2·a-1). Soil samples were separately collected from the 0~10 cm and 10~20 cm soil layer. The results showed that nitrogen deposition significantly affected the structure of fungi community. the relative abundance of fungi in the phyla,class and genus level were significantly different at the 0~10 cm and 10~20 cm soil layer of nitrogen deposition treatment. The response of soil fungal community to nitrogen deposition at the 0~10 cm soil layer and 10~20 cm soil layer was significantly different,and there was obvious soil gradient effect. Canonical correspondence analysis (CCA) showed that soil pH,soil total organic C,NO3-N and available P were key environmental factors leading to the shift in the soil fungal community composition. In conclusion,nitrogen deposition changed the soil chemical properties,which drove the change of soil microbial communities and soil fungal communities. © 2019 China Agricultural University. All rights reserved.     

Effects of Exogenous Glycine Betaine on the Physiological Characteristics in Medicago sativa Seedlings under Low-temperature Stress北大核心CSCD

In this study,the 'Ganong 5th' alfalfa (Medicago sativa L.) was used as experimental material,and two application methods (leaf application,root application) and six exogenous betaine concentrations (0,10,20,30,40 and 50 mmol·L-1) were used to treat the seedlings of alfalfa. Plant growth and related physiological indexes were measured after 7 days of low temperature (4?) stress,and the physiological mechanism of exogenous betaine to alleviate the low temperature stress of alfalfa was explored. The results showed that exogenous GB alleviated the loss of plant height,root length,leaf dry weight,root dry weight and chlorophyll content,and increase the content of soluble sugar (SS) and free proline (Pro),and reduced the increase in leaf relative membrane permeability and MDA content. Exogenous GB increased antioxidant enzyme activities and non-enzymatic antioxidant content. And also,exogenous GB enhanced the osmotic adjustment capacity of the plant by increasing endogenous GB accumulation and BADH activity. These results indicated that exogenous GB enhanced the resistance of Medicago sativa to low-temperature stress under low temperature adjustment. The membership function analysis indicated that spraying 30 mmol·L-1 GB on the leaves and spraying 40 mmol·L-1 GB on the roots had the best effect on alleviating the low-temperature stress of alfalfa seedlings. © 2019 Ｊｏｕｒｎａｌ ｏｆ Ｒｅｆｒｉｇｅｒａｔｉｏｎ. All rights reserved.     

Characteristics of Evapotranspiration and Water Consumption of Typical Alpine Desert in the Tibetan Plateau During the Growing Season北大核心CSCD

To explore the law of water consumption in the underlying surface of a typical alpine desert on the Qinghai-Tibet Plateau, we analyzed the characteristics of ET change and water consumption on different time scales based on the raw eddy-covariance data and meteorological data measured in April to August 2019 from the observation tower on Tuotuohe weather station. The maximum hourly average ET appears at 2-3 p. m, reaching 0.46 mm·h-1; The maximum value of daily ET was 8.58 mm·d-1 on July 7, and the minimum value was 0.30 mm·d-1 on April 2; The ET increased first and then decreased during the growing season, the monthly ETmax was 120.68 mm in July and the ETmin was 64.80 mm in April; The total ET in 2019 growth season was 581.15 mm and the daily average was 4.01 mm. The total precipitation of the whole growing season was 235.70 mm, according to the difference between ET and precipitation(Pr) from April to August, water vapor exchange during the plant growth season was mainly characterized by water consumption on the land surface in 2019. © 2019 Authors. All rights reserved.     

Characteristics of Nutrient Contents and Evaluation of Nutritional Value of the Alpine Grassland Plants in the Source Area of the Yellow River北大核心CSCD

In order to explore the characteristics of nutrient contents and scientifically evaluate the nutritional value of the alpine grassland plants in the source area of the Yellow River, the plants of the five different alpine grasslands were selected as the research objects, and the content of crude protein (CP), ether extract (EE), crude fiber (CF), crude ash (CA), total phosphorus (TP) of the plants were determined. At the same time, the principal component analysis method was used for quantitative comprehensive evaluation of the plants nutritional value. The results showed that the CP content of the plants in all alpine grasslands was between 12.78%~15.35%, the EE content was between 2.63%~3.38%, the CF content was between 17.56%~25.16%, the CA content was between 5.52%~11.53% and the TP content was between 0.11%~0.27%. The order of nutrient value of plants in different alpine grassland from high to low was: degraded alpine meadow > native alpine meadow > swamp meadow > degraded alpine steppe> native alpine steppe;The order of yield per unit area of the total nutrients of plants in different alpine grasslands from high to low was: swamp meadow > native alpine meadow > native alpine steppe> degraded alpine steppe> degraded alpine meadow;The order of nutrient value of different plant species from high to low was: Leguminosae>Forbs >Cyperaceae>Gramineae. © 2019 Authors. All rights reserved.     

Effects of Grazing on Vegetation Characteristics and Forage Nutrientional Quality in a Temperate Desert Steppe北大核心CSCD

Grazing and fencing field were sampled to explore their effects on vegetation characteristics and forage nutritional quality by the combined analytical method in the temperate desert steppe. The results showed that, grazing significantly decreased the height, coverage and biomass of the plant community, and significantly increased the species richness index (P<0.01). Moreover, grazing significantly increased the Crude protein (CP), Crude fat (CF), Dry matter digestibility (DMD) and Metabolic energy (ME), and significantly decreased the Neutral detergent fibers (NDF) and Acid detergent fibers (ADF) (P<0.01). The species richness index was positively correlated with CP, CF, DMD and ME, but negatively correlated with NDF and ADF (P<0.01). CP, CF, DMD and ME were negatively correlated with NDF and ADF (P<0.01). In summary, grazing significantly increased species richness index and forage nutritional quality. Therefore, it is recommended to carry out appropriate grazing on the fencing temperate desert steppe to make full use of grassland resources and protect species diversity. © 2019 Authors. All rights reserved.     

Dynamic Characteristics of Soil Sucrase and Amylase Activities during Vegetation Degradation in Gahai Wetland北大核心CSCD

In order to study the activities and dynamic characteristics of soil invertase and amylase during the process of vegetation degradation (Non-degradation, Light degradation,Moderate degradation, and Heavy degradation),the filed experiments were conducted in marsh meadow of Gahai wetland in Gannan state,Gansu province. The main results were as following: the average activity values of invertase and amylase activities in 0~100 cm layers varied in different stages of vegetation degradation of marsh meadow, following the order of CK (Non-degradation) > SD (Light degradation) > MD (Moderate degradation) > HD (Heavy degradation). With the increasing of soil layers,the activity of invertase significantly decreased (P<0.05),while the activity of amylase decreased fluctuantly. The activities of enzymes in the surface soil (0~20 cm) accounted for more than 60% of the total activities of each enzyme. The activities of invertase and amylase showed the obvious dynamic characteristics with time in all stages of vegetation degradation. The average activity of invertase in different months was the highest in June (47.07 mg·g-1) and the lowest in August (22.69 mg·g-1). The average activity of amylase was the highest in July,85.18 mg·g-1,while the activity values in other months were low. Correlation analysis showed that soil organic carbon was significantly correlated with invertase and amylase (P<0.01),and soil water content was only significantly correlated with invertase (P<0.01). The results showed that the vegetation degradation in Gahai wetland significantly affects soil invertase and amylase activities,reduces the efficiency of enzymatic reaction,and leads to the deterioration of wetland soil environment. © 2019 Ｊｏｕｒｎａｌ ｏｆ Ｒｅｆｒｉｇｅｒａｔｉｏｎ. All rights reserved.     

Effect of Different Planting Patterns on the Production Characters and Forage Quality of Alfalfa in Haihe Plain北大核心CSCD

To eplore the effects of different planting methods on the production traits and forage quality for alfalfa in Haihe Plain. Field experiments were conducted in 2013 to 2016 by setting different row space, including 10 cm row space, 20 cm row space, 30 cm row space, 20-40 cm wide and narrow row sowing and spreading under the same amount of seeding The variation of plant height, leaf-to-stem ratio, hay yield, lo-ding drage, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein and relative feed value, were analyzed. The results showed that there were no significant differences in plant height, leaf-to-stem ratio in the same year and same cutting under the different planting mehods (P > 0. 05). The hay yield of 1st cutting with 20-40 cm row space treatment was significant lower than 30 cm row space (P< 0. 05). However, the first two cutting hay yield, total hay yield of the 20-40 cm row space were significant higher than that of in 30 cm row space treatment (P > 0. 05). There were no significant differences in forage quality under the different planting pattern treatment (P > 0. 05). The lodging of the 20-40 cm row space and 30-30 cm row space treatment were relatively light. According to the comprehensive results, all the planting pattern with broadcast seeding, equal row sapcing of 10 cm to 30 cm, and wide and narrow row of 20-40 cm will be suitable for cultivation in haihe plain, which depend on the actual situation. © 2019 China Agricultural University. All rights reserved.     

Research on the Effect of Plant Combination Types on the Shear Strength of the Root-soil Composite System of Alpine Grassland in the Source Region of the Yellow River北大核心CSCD

In this study,an alpine grassland in Henan County,Qinghai Province,in the source region of the Yellow River,was selected as the study area. The shear strength of root-soil composite system characteristics of 6 different plant combination types of grassland were explored by field investigation and sampling and indoor tests,which aimed to provide a theoretical basis for preventing and controlling soil erosion and shallow landslide caused by grassland degradation. The test results showed that the shear strength of root-soil composite system of 6 different combinations was a increasing trend with the decrease of altitude. Namely,the shear strength of the root-soil composite system of Stipa purpurea Griseb. + Kobresia pygmaea C. B. Clarke at the top of the sunny slope was 27.76 kPa and the value of Elymus nutans Griseb. at the bottom of the sunny slope was 37.53 kPa. The reasons why the shear strength of 6 kinds of combinations varied from large to small with the decrease of altitude were related to their density,moisture content,root content and dry weight of roots in the root-soil composite system samples. That is,the root content of composite system at the top,middle and bottom of the sunny slope were 6.2%,5.5% and 16.2%,respectively. The values at the top,middle and bottom of the shady slope were 8.0%,11.4% and 31.6%,respectively. © 2019 China Agricultural University. All rights reserved.     

Study on Water Consumption Characteristics of Compound Green Space in Urumqi Xinjiang北大核心CSCD

In order to ascertain water consumption characteristics of typical compound green space (CGP) which composed of turf and white elm in Urumqi city. Field irrigation experiment with fixed irrigation frequency and changed irrigation quota was carried out in Hongshan Park Urumqi. The results showed that average daily water consumption (ADWC) of lawn and white elm in CGP increased with the increase of irrigation quota,and showed the same trend of single peak curve (increased first and then decreased with the development of growth period). Cumulative water consumption of CGP in each treatment varied between 668.5~996.4 mm,which increased with the increase of irrigation quota. The ratio of water consumption between lawn and elm in CGP varied from 1:1 to 1:1.2,which increased first and then decreased with the increase of irrigation quota. The crop coefficient of CGP in each treatment during May to September varied between 0.72 and 1.52,and the average value of crop coefficient in each treatment during main growth period increased with the increase of irrigation quota. Considering the water consumption and growth of CGP,in the dry year with 75% rainfall frequency,the suitable irrigation quota of similar CGP with similar maintenance level is 36 mm,and the irrigation period is 5~7 days in Urumqi city. © 2019 Ｊｏｕｒｎａｌ ｏｆ Ｒｅｆｒｉｇｅｒａｔｉｏｎ. All rights reserved.     

Characteristics of Forage Nutritional Quality and Digestibility in Different Types of Grassland in Qinghai Tibet Plateau and their Correlation北大核心CSCD

In order to explore the differences of forage nutritional quality and digestibility among different types of rangelands, five typical rangeland types (alpine meadow, alpine steppe, warm steppe, desert steppe and warm desert steppe) in Qinghai-Tibet Plateau were used as research objects. The characteristics of forage nutritional quality and digestibility of typical rangelands and their correlation were analyzed. The results showed that: there were significant differences in crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF) and dry matter digestibility (DMD) among different types of rangeland (P<0.01). The results of Pearson correlation analysis showed that there was a significant positive correlation between DMD and CP (P<0.05), and a significant negative correlation between DMD and NDF and ADF (P<0.05). Elevation (ELE) was positively correlated with DMD and CP (P<0.05), but negatively correlated with NDF and ADF(P<0.05). In conclusion, there were significant differences in CP, ADF, NDF and DMD among different types of grasslands in Qinghai-Tibet Plateau, and it mainly manifested that with the increase of altitude, ADF and NDF gradually decreased, while CP and DMD gradually increased, and forage quality gradually increased. © 2019 Authors. All rights reserved.     

Effects of Compound Bacteria Preparation on Fermentation Quality and Rumen Fermentation Characteristics of Phragmites australis Silage北大核心CSCD

The purpose of this study was to investigate the effects of compound bacteria preparation (including homogeneous Lactobacillus/heterogeneous Lactobacillus, Bacillus subtilis and Aspergillus niger as well as their compatibility) on nutrient composition, fermentation quality and rumen fermentation characteristics of Phragmites australis silage. Taking growing Phragmites australis from Dongting lake as silage material, five groups were set up, which were blank group (CK group), lactic acid bacteria group (LA group, supplemented with Lactobacillus plantarum, Pediococcus pentosaceus and Lactobacillus buchneri), lactic acid bacteria+Bacillus subtilis group (LA+BS group), lactic acid bacteria+Aspergillus niger group (LA+AN group) and lactic acid bacteria+Bacillus subtilis+Aspergillus niger group (LA+BS+AN group), and each group had 3 replicates. The supplemental level of lactic acid bacteria was 1.5×108 CFU/kg silage raw materials, and the supplemental levels of Aspergillus niger and Bacillus subtilis were 1.0×108 CFU/kg silage raw materials (all were based on fresh weight of silage raw materials). After 60 days of silage, the nutrient composition and fermentation quality of Phragmites australis silage were determined, and the rumen fermentation characteristics were evaluated by in vitro fermentation and in vivo degradation. The results showed as follows: 1) the contents of dry matter and ash in LA, LA+BS and LA+AN groups were significantly lower than those in CK group (P<0.05), and the crude protein content in LA+BS, LA+AN and LA+BS+AN groups was significantly higher than that in CK and LA groups (P<0.05). 2) The silage sensory evaluation scores of all groups were 60 to 70 points, and the ratings were good. The comprehensive scores of fermentation quality in LA+BS and LA+AN groups were higher, among which, the ammonia nitrogen to total nitrogen ratio, acetic acid content and acetic acid to total acid ratio in LA+AN group were significantly decreased compared with CK group (P<0.05), while the lactic acid content and lactic acid to total acid ratio were significantly increased compared with CK group (P<0.05). 3) The dry matter disappearance rate and total gas production of in vitro fermentation in LA+AN group were significantly higher than those in the other groups (P<0.05), and in vitro fermentation parameters such as volatile fatty acid contents in fermentation liquid were improved. 4) The rumen fermentation dry matter degradation rate in LA+AN and LA+BS+AN groups at 8, 24 and 48 h was significantly higher than that in the other three groups (P<0.05). In conclusion, the combined application of lactic acid bacteria and Aspergillus niger with supplemental levels in this experiment has the best effect on the quality of Phragmites australis silage and rumen fermentation characteristics. © The Author(s) 2023.     

Effects of Melatonin on Gastrointestinal Tract Physiological Function of Ruminant北大核心CSCD

褪黑素(MT)是调节胃肠道运动、免疫功能及微生物菌群结构等的胺类激素,其前体物质(色氨酸)是微生物群-肠-脑轴的信号递质。目前有关MT的研究多集中于单胃动物,鲜见MT对反刍动物的综述报道。因此,本综述将从MT对反刍动物胃肠运动、摄食行为、生产性能以及胃肠道微生物的作用机制进行阐述,以期为MT作为反刍动物治疗辅助剂、饲料添加剂的价值提供参考。     

Effects of Bacillus amylolyticus on Rumen Dry Matter Digestibility,Fermentation Parameters and Metabolites of Dairy Cows北大核心CSCD

This experiment was conducted to study the effects of Bacillus amylolyticus on rumen dry matter digestibility, fermentation parameters and metabolites of dairy cows. Experiment 1: six dairy cows with permanent fistula and had the similar parity (2 to 3 fetuses), body weight [(662 ±57) kg], lactation days [(160 ± 22) d] and milk yield [(36.1 ±3.8) kg / d], were randomly divided into 3 groups with 2 cows per group. Using 3 ×3 Latin square design, each group was extra fed 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, the trial period was 3 periods, 13 days for each period, including 10 days for the pre-trial period and 3 days for the trial period. At the beginning of the trial period, the rumen dry matter digestibility of cows was measured by nylon bag method. Experiment 2: thirty dairy cows with similar parity [(2.5 ±0.3) fetuses], initial body weight [(559.2 ± 7. 4) kg], milk yield [(35. 2 ± 1. 5) kg / d] and lactation days [(99 ± 22) d] were randomly divided into three groups with 10 cows in each group. Cows in the 3 groups were extra fed with 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, respectively. The pre-trial period was 10 days and the trial period was 42 days. The rumen fluid was collected on the last day of the trial period, and the rumen fermentation parameters and metabolites were determined. The results showed as follows: compared with the control group, 1) supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 12, 24, 36, 48 and 72 h (P <0.05), supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 36 and 48 h (P <0.05); 2) supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid, butyric acid, isovaleric acid, valeric acid, total volatile fatty acid and microbial protein in the rumen of dairy cows (P < 0. 05), supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid and isovaleric acid in the rumen of dairy cows and significantly reduce the rumen acetic acid / propionic acid (P < 0. 05), supplementary feeding of 5 ×109 and 5 ×1010 Bacillus amylolyticus had no effects on rumen pH and ammonia nitrogen content (P >0.05); 3) eleven metabolic pathways related to differential metabolites were detected, and ascorbic acid and alginate metabolism were significantly enriched (P < 0. 05) . In conclusion, Bacillus amylolyticus can increase the rumen dry matter digestibility, and improve the rumen fermentation function of dairy cows by affecting the content of rumen metabolites. By comprehensive analysis, supplementary feeding of 5 × 109 CFU / d Bacillus amylolyticus can achieve better effect. © 2023 Authors. All rights reserved.