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Grasslands represent an important green ecological barrier in the terrestrial environment. The north Chinese grassland accounts for 40.72% of the total grassland area in China. Using satellite data on vegetation index, this study analyzed vegetation dynamics in the north Chinese grassland over the past 20 years, from 2000 to 2019. It was found that from 2000 to 2019, the vegetation index of China’s northern grassland showed a significant growth trend (P < 0.01), with an annual increase of 0.0029 in normalized difference vegetation index and a stable growth rate of 24% over this 20-year period. From 2000 to 2019, the northern grassland showed overall vegetation restoration despite partial vegetation degradation in some areas; areas where vegetation was restored accounted for 52.22% of the grassland, while areas where it was degraded accounted for 0.86%. The effects of this restoration were most obvious at lower latitudes and in humid and semi-humid regions. Areas with no obvious change were mainly distributed in higher latitudes and arid regions, where natural conditions are very poor and vegetation restoration is more difficult. More attention should be given to the long-term and continuous restoration of the grassland.
Based on Landsat remote sensing images from 2000, 2010, and 2017, this study quantitatively analyzed the land use change pattern and ecological environment quality of Yanchi County from 2000, using ENVI, ArcGIS, and other software. The results showed that grassland area, unused land, and cultivated land in Yanchi County shrunk, while forest land (mainly shrubs) and construction land continued to increase from 2000 to 2017. Land use change was frequent between woodland, grassland, cultivated land, and unused land, and most of them were distributed in the northeast of the region. The index of land use structure showed that the orderliness and stability of the land use system in Yanchi County increased, especially in large disturbed areas, and its stability was stronger than that in weakly disturbed areas. The environmental quality showed two main directions: improvement and deterioration, with improvement being the dominant trend; different townships (towns) showed obvious regional differentiation characteristics. The main factors leading to changes in the ecological environment were government policies, including the implementation of the policy of returning farmland to forestry and grassland, sand control and desertification control (2000), the construction of Haba Lake Reserve (2006), and the prohibition of grazing (2002). A large number of unused lands had been converted to grassland and woodland with a higher environmental quality index, which contributed to the improvement of the environment in the study area to as high as 6.5%.
Soil moisture is one of the key factors affecting the ecological capacity and regeneration of alpine grassland in the Qinghai-Tibet Plateau. Using the temperature–vegetation dryness index (TVDI), we analyzed spatiotemporal variation and dynamic trends in soil moisture during the growing season in this area. In order to study the response of soil moisture to climate factors, correlation analysis was used to combine these data with data from meteorological stations in the study area. The results showed that during growing season from 2001 to 2018, the soil was on average humid in the northern part of the hinterland of the Qinghai-Tibet Plateau, while it was arid in the northeast and southwest. The proportions of wet, moist, normal, arid, and dry soil were 1.14%, 29.24%, 37.68%, 30.09%, and 1.85%, respectively. In the past 18 years, the soil in the southern part of the study area showed a significant drying trend, while that in the north and northeast tended to become wetter. Soil moisture decreased in most areas. The northern and northeastern regions of the study area were significantly affected by precipitation, while the southwestern region was significantly affected by temperature.
The source region of the Yellow River (SRYR) lies in the northeastern Qinghai-Tibetan Plateau. The SRYR is a typical alpine region that is fragile and vulnerable. Ligularia virgaurea, one of the main toxic weeds, is widely distributed in the SRYR. There are few studies on the spatial-temporal distribution of L. virgaurea at a regional scale, and the most important limiting factor is the lack of broad scale, precise, and efficient monitoring methods. We proposed a practical method based on unmanned aerial vehicles (UAVs) and a widely used species distribution model, BIOdiversity MODelling (BIOMOD), and tested it to determine the distribution of L. virgaurea in the SRYR. During the growing season of 2018, we set 208 working points using the self-developed software-fragmentation monitoring and analysis with aerial photography (FragMAP) and obtained more than 5000 aerial photographs in the SRYR. Based on the data, we simulated the distribution of L. virgaurea using the 10 models in BIOMOD. The results showed that: 1) BIOMOD could reduce the uncertainty and improve the prediction performance of L. virgaurea distribution; 2) the generalized boosting model exhibited the best performance in predicting the potential distribution of L. virgaurea in SRYR, while the random forest model was the best at predicting its distribution in the future; the main factors affecting its distribution were the microhabitat (maximum value, average value, and ranges of normalized difference vegetation index), annual average radiation, radiation in cold and wet season, and precipitation in the wet season; and 3) climate warming may increase the distribution of L. virgaurea in SRYR, especially in the southeastern central area. This study described the spatial-temporal distribution of L. virgaurea, which provides basic data for estimating the damage rating and for implementing prevention measures in a rational and timely manner. Furthermore, it could provide a scientific basis for the sustainable development of grassland ecosystems and animal husbandry in the SRYR. Meanwhile, the UAVs-based monitoring featured with long-time, large scale and high precision, provided abundant data and a new method for biodiversity research and conservation in the alpine grassland ecosystem.
Urban grassland areas are expanding as urbanization accelerates, and their role in the regional carbon cycle is becoming increasingly important. The carbon emissions of urban grassland ecosystems hold significance for the construction of urban green spaces and low-carbon cities. We used the LI-8100 soil gas flux system to determine the ecosystem respiration (ER) and related hydrothermal factors of five common urban grassland ecosystems in Guiyang City from April to October 2018. We found that the ER showed obvious seasonal changes, with average emissions ranked as follows: Trifolium repens > Lolium perenne > Cynodon dactylon > Ophiopogon japonicus > Ophiopogon bodinieri. ER was positively correlated (P < 0.05) with soil temperature at 5 cm and air temperature, but negatively correlated ( P < 0.05) with soil water content. The Q10 values of air temperature and soil temperature were 1.22～2.06 and 1.15～1.85, respectively. The cumulative emissions of Trifolium repens and Lolium perenne were significantly higher than those of Cynodon dactylon, Ophiopogon japonicus, and Ophiopogon bodinieri (P < 0.05). Cumulative ER emissions were significantly positively correlated ( P < 0.05) with total soil nitrogen, aboveground biomass, soil microbial carbon, and soil urease. Our study shows that there are significant differences in CO 2 emissions between different types of grasslands and that these are affected by multiple factors, such as hydrothermal conditions and soil nutrients, indicating that grass type should be taken into consideration in planning for low-carbon urban development.
To determine the effect of subsoil crusts on the distribution pattern of Limonium species in Haloxylon ammodendron forest, we chose L. aureum in a degraded H. ammodendron forest in Shiyang River basin as the research subject and determined the distribution pattern of L. aureum in the no crust stage (NCS), physical crust stage (PCS), and biological crust stage (BCS). The results showed that (1) the formation of soil crusts played a positive role in seed capture, germination, and settlement of L. aureum. Owing to the high ground mobility, it was difficult to obtain suitable germination conditions for seeds in non-crusted areas. Therefore, the population density of L. aureum in the NCS plot was significantly lower than that in the PCS and BCS plots (P < 0.05). (2) The height of L. aureum was not significantly different in the different soil crust types (P > 0.05). The average crown width of L. aureum in the PCS and BCS plots was significantly lower than that in the NCS plot (P < 0.05), whereas the population coverage of L. aureum in the PCS and BCS plots was significantly higher than that in the NCS plot (P < 0.05). Soil crust formation caused a redistribution of precipitation, which affected the growth of the population. (3) The population distribution of L. aureum in the NCS plot was sparse and uneven, and was the small plant type. The population distribution of L. aureum in the PCS and BCS plots was dense, forming a stable population, and the number of large plants was higher than the number in the NCS plot. (4) In the NCS, PCS, and BCS plots, the spatial distribution pattern of the population of L. aureum showed aggregation distribution; however, the aggregation intensity was different. The order of the aggregation intensity was as follows: BCS > PCS > NCS. Thus, the crust type influenced the basic characteristics, age structure, and spatial distribution pattern of the L. aureum population significantly. Crust formation promotes the settlement and distribution of the L. aureum population. The population density is large and relatively stable. The study provides a reference for the restoration of artificial vegetation of degraded H. ammodendron.
Sulfur is an indispensable mineral nutrient element, which required for the growth and development in animals and plants, and plays an important role in organic husbandry. The purpose of this study was to characterize the distribution of soil total sulfur, nitrogen, phosphorus, and potassium nutrients in different meadow types and topographies, and to explore the relationships between soil total sulfur and other nutrients in Hequ grassland of Qinghai, China. The total sulfur content of soil and plant samples was analyzed by ICP-OES (iCAP6300), and the contents of total nitrogen, phosphorus, potassium, organic matter, and soil pH were determined by conventional soil nutrient analysis. There were significant differences in the sulfur content in both soil and plant samples from different meadows, but no significant differences were detected in both soil and plant samples from different terrains. The soil total sulfur content in the study area was 1 023.98 mg·kg−1, and plant total sulfur content was 4 120.20 mg·kg−1. The average soil organic matter, total nitrogen, total phosphorus, and total potassium contents were 134.35, 6.44, 1.95, and 23.05 g·kg−1, respectively, and were higher than the average levels of these in the Qinghai-Tibet Plateau. Soil total sulfur content was positively correlated with organic matter content, aboveground biomass, and plant total sulfur (P < 0.05). Soil carbon : sulfur ratio was between 58.90 and 102.18, indicating that soil sulfur was in a net release phase. The current production mode that the element has only output and no human input has not resulted in a soil sulfur deficiency, and sulfur is not a limiting factor for soil nutrients and the livestock industry in Henan County.
A large number of soil excavation and deposition sites which were produced during highway construction on the Qinghai-Tibet Plateau have been restored over time, however, there is still considerable uncertainty regarding whether the restored grassland ecosystem is sustainable. This study examined restored grassland at abandoned soil excavation sites along the Gonghe-Yushu Expressway (hereinafter referred to as Gongyu Road) and compared differences in vegetation community height, coverage, species richness, Shannon-Wiener index, Simpson diversity index, and grassland plant community structures between the abandoned soil excavation site grassland and corresponding natural grasslands. The results showed that vegetation community coverage, species richness, Shannon-Wiener index, Simpson diversity index, and community structure differed significantly between excavation sites and natural grassland (P < 0.05). The vegetation community height of excavation site grassland was significantly lower than that of natural grasslands ( P < 0.05), while height of the vegetation community in excavation site grassland of the high-altitude sample plot was not significantly different from that of natural grassland ( P > 0.05). In summary, grassland coverage has increased after four years of grass reseeding in abandoned excavation site grassland, however, the overall restoration effect did not restore used sites to natural grassland. Taken together, the grassland-restoration effect on abandoned excavation site grassland is not sufficient in this region.
The spatial expansion ability of clonal plants can help them successfully colonize adverse habitats and make efficient use of patchily distributed resources, which is crucial for growth and adaptation of such plants. Spatial expansion characteristics of clonal plants also hold considerable potential for restoration of degraded ecosystems. One important characteristic of clonal plants is physiological integration, which consitutes resource translocation and sharing between ramets (i.e., potentially physiologically independent units or individuals) connected by horizontal structures such as rhizomes, stolons, and horizontally growing roots. In this review, adaptive strategies of clonal plants to colonize heterogeneous habitats are summarized. Based on physiological integration, clonal plants enhanced the division of labor by modifying phenotypic plasticity, foraging behavior, and the tradeoff of biomass allocation; thus, ramets in heterogeneous patches performed “specialization for abundance”, which substantially improved resource use efficiency and adaption potential. Moreover, based on the “C–S–R (competition–stress–ruderal)” life history strategy theory, effects of environmental factors including disturbance, stress, and competition on spatial expansion of clonal plants are discussed, and the driving mechanisms of expansion were also revisited. We assumed that intermediate disturbance (e.g., grazing, mowing, etc.) may improve spatial expansion of clonal plant populations. Furthermore, we summarized the application potential of expansion of clonal plants for the restoration of degraded ecosystems. Clonal plants produce large and dense multilayered rhizomes/roots during the expansion process which increases soil consolidation and sand fixation, improves water conservation capacity, and thus ameliorates the soil environment. Moreover, propagules of clonal plants play a pioneering role in colonizing poor or bared habitats, which is important for species diversity regeneration, community structure variation, and productivity in degraded ecosystems. Based on their expansion functions in both above- and below-ground environmental recovery, clonal plants improve the restoration succession of degraded ecosystems. It is suggested that future research should focus on spatial expansion of clonal plants from the perspective of restoration of degraded environments in order to increase knowledge on the overlapping fields of clonal plant biology and restoration ecology and to provide a new research ideas for the restoration and management of degraded grasslands.
The effects of different storage conditions and hydroponic solutions on bulbil germination and growth of Polygonum viviparum were investigated to determine the best methods for large-scale cultivation. Bulbils were stored in four ways (dry storage at room temperature, dry storage at 4 ℃, sand storage at room temperature, and sand storage at 4 ℃), and the effects on their germination were studied. Additionally, investigations were performed into the effects of five different hydroponic nutrient solutions on seedling growth and the fresh weight of new pseudobulbs. All four storage methods had a significant effect on bulbil germination (P < 0.05). Bulbils germinated normally after short-term sand storage at room temperature. For bulbils stored in sand at 4 ℃, germination rate, germination time, seedling survival rate, and new pseudobulb growth remained unaffected even after up to one year ( P > 0.05). In addition, each of the five nutrient solutions produced better growth in the aboveground parts of P. viviparum than the control group. Plants treated with nutrient solution formula V had the most developed root system, showing better growth than the control group. However, the root systems of plants treated with other nutrient solutions were less developed than in the control group. Moreover, the fresh weight of the pseudobulbs was higher in plants treated with all five nutrient solutions than in the control group, with nutrient solution V producing the greatest weight. In summary, sand storage at 4 ℃ was the most suitable storage method for P. viviparum bulbils, and nutrient solution formula V [Ca(NO3)2·4H2O 1 180 mg·L−1, KNO3 505 mg·L−1, KH2PO4 55 mg·L−1, MgSO4·7H2O 369.7 mg·L−1, H3BO3 2.86 mg·L−1, ZnSO4·7H2O 0.23 mg·L−1, CuSO4·5H2O 0.07 mg·L−1, (NH4)6Mo7O24·4H2O 0.025 mg·L−1, MnSO4·4H2O 2.12 mg·L−1, Na2Fe-EDTA 52.084 mg·L−1] was the most suitable for the hydroponic cultivation of P. viviparum.
Zygophyllum xanthoxylum is an extremely xerophytic shrub that is strongly resistant to stress and is important both ecologically and for its feeding value. The two-factor effect of sowing depth (0, 1, 4 cm) and irrigation frequency (0, 1, 2, 3, 4, or 5 times during the study period) on the emergence and establishment of Z. xanthoxylum seedlings was studied in an experimental field in Minqin County, Gansu Province, China. In addition, the overwintering rate, phenological cycle, and growth and development of Z. xanthoxylum were compared between sites in Minqin and Yuzhong Counties. Z. xanthoxylum seedlings had the fastest emergence and establishment when the seeds were planted at 1 cm. At this depth, the rates of emergence and establishment were significantly higher when seedlings were irrigated 2, 3, or 4 times than when they were irrigated 5 times or not at all, with no significant difference among groups when the seedlings were irrigated 2, 3, and 4 times (P > 0.05). Taking water conservation into consideration, the treatment in which the seeds were sown at 1 cm and irrigated twice could be considered the best, with seedling emergence and establishment rates of 69% and 49%, respectively. During the second year of establishment, there was no significant difference between the two test sites regarding the overwintering rate of Z. xanthoxylum seedlings, which was above 90% at both (P > 0.05). At the Minqin test site, regreening, first flowering, peak flowering, and first fruiting took place 4～6 days later than in Yuzhong, and yellowing took place 38 days later, while the fruit ripened 4 days earlier. Furthermore, the duration of flowering in Minqin was 4 days longer than in Yuzhong, and the growth period was 35 days longer. At both sites, the plants reached maximum height at the fruit ripening stage (108 cm in Minqin; 79 cm in Yuzhong). The number of first-level branches was 6.3 in Minqin and 5.7 in Yuzhong, which was not a significant difference ( P > 0.05). However, the number of secondary branches was 23.5 in Minqin vs. 11.8 in Yuzhong, which was a significant difference ( P < 0.05). The pod setting rate (6.3%, 5.1%) and the seed yield per plant (3.2, 1.9 g) were also higher in Minqin than Yuzhong.
To explore the effects of forage crop collocation and stripe configuration on the above-ground biomass and competitiveness in an intercropping system, as well as screen out the intercropping combinations and patterns suitable for cultivation in the semi-arid areas of Northwest China, three forage crop collocations, corn||sorghum hybrid sudangrass, corn||oat, and sorghum hybrid sudangrass||oat, and three stripe configurations, wide row (460 cm), middle row (300 cm), and narrow row (140 cm), were set up in this experiment. The above-ground biomass, yield increase rate, contribution rate of increasing yield, land equivalent ratio (LER), relative crowding coefficient (RCC), competition ratio (CR), actual yield loss index (AYL), and system productivity index (SPI) were tested in each intercropping system. The results showed that the intercropping system had certain advantages, with LER > 1 and AYL > 0, and the system increased the yield rate to 19.63%～40.49%. In intercropping systems, the sorghum hybrid sudangrass was a competitive dominant species relative to corn and the competitiveness of oat was greater than that of corn and sorghum hybrid high grass. The system yield, LER, AYL, and SPI of the corn||sorghum hybrid sudangrass collocation peaked in the middle row pattern, with land utilization exceeding that of the monoculture by 20.2%, thereby achieving the best productivity and resource utilization efficiency.
Pigeon pea (Cajanus cajan) is a legume species used for both medicine and food. This study compared 10 pigeon pea accessions with respect to leaf water content, active components in extracts, total flavonoids, polysaccharides, and external morphological characteristics and then analyzed the metabolic differences of 4 different accessions (3-QZ, 4-HK, 5-DH3, and 6-DZ). There was abundant variation in morphological characters, with the variation coefficient ranging from 8.75% (hundred-seed weight) to 37.96% (number of branches). There were significant correlations (P < 0.05) between moisture content and leaf length, active components in extracts and pod length, leaf shape index and inflorescence axis length, inflorescence axis length and banner petal size, inflorescence axis length and pod width, pod length and hundred-seed weight, and pod width and hundred-seed weight. Total flavonoid content was significantly correlated with banner petal size, leaf length and width, leaf shape index, pod width, and hundred-seed weight ( P < 0.01), and there were significant differences with regard to active components ( P < 0.05). Four pigeon pea accessions were analyzed to determine their metabolite content, and 453 compounds were obtained, which included lipids, organic acids, terpenes, alkaloids, tannins, amino acids and their derivatives, phenolic acids, nucleotides and their derivatives, flavonoids, quinones, lignans, coumarins, and other compounds, of which flavonoids were the most dominant; there were significant differences among different accessions ( P < 0.05). This study provides a reference for the breeding of new varieties of pigeon pea and the analysis of active components of this plant.
To determine the diversity and harmfulness of weed species in citrus orchards in the Three Gorges Reservoir Region, 255 quadrats in 51 citrus orchards were investigated using a five-point pattern. A total of 185 weed species were found, belonging to 146 genera in 53 families, of which Compositae, Gramineae, Polygonaceae, Apiaceae, and Amaranthaceae were the most dominant. We identified 15 species (Alternanthera philoxeroides, Digitaria cruciata, Cyperus rotundus, Bidens biternata, and others) as priority targets for control. In addition, it was found that the citrus orchard weed communities showed a clear trend of succession toward climax. Therefore, the main objective of weed control in citrus orchards should be to mitigate or inhibit the succession of climax species, and the regional control strategy should be based on interspecies relationships. This study provides an important reference for weed control and optimal management of citrus orchards in the Three Gorges Reservoir Region.
During abiotic stress, senescence may occur in plant cells in order to avoid stress, which is manifested in accelerated chlorophyll degradation, decelerated photosynthesis, protein degradation, and increased concentrations of reactive oxygen species, which leads to premature plant growth and reduces yield and quality. Abiotic stress-induced senescence manifests in typical physiological and molecular stress responses which are regulated by hormones and senescence response genes. Almost all stresses induce production of heat shock proteins (HSPs), whose transcription is regulated by heat shock factors. HSPs are molecular chaperones that assist in the correct folding or assembly of proteins, prevent irreversible protein aggregation, and participate in protein transmembrane transport and target protein degradation and other biological functions to maintain cell stability under poor developmental conditions. This article reviews the physiological and biochemical changes in plant senescence and HSP responses under abiotic stress so as to provide a reference for further research on plant abiotic stress tolerance.
In this study, four mixed diets with different proportions of oat grass and alpine meadow natural herbage were used to carry out a simulated grazing experiment. The effects of summer cultivated different proportions of oat grass were mixed with natural herbage feeding on the digestion and metabolism of grazing Tibetan sheep were subsequently studied. Our results showed that the intake and digestibility of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF) and acid detergent fiber (ADF) decreased with increasing oat grass proportions. A greater than 50% of oat grass significantly reduced the DM and OM intake and digestibility in Tibetan sheep (P < 0.01). The fecal nitrogen content presented a concave parabola change with increasing nitrogen intake. When the daily nitrogen intake was 4.65 g, the daily fecal nitrogen content was the lowest, at 1.13 g. As nitrogen intake increased, the digestibility of nitrogen presented a convex parabola. The digestibility of nitrogen was the highest, at 76.53%, when the daily nitrogen intake was 5.60 g. Total energy intake decreased with the increase of oat grass ratio. In conclusion, in summer, all natural herbage can meet the growth and metabolism of Tibetan sheep, and it is not suitable to feed additional oat grass.
The objective of this study was to evaluate the effects of dietary supplementation with rape on the in vitro fermentation of rumen fluid from Tan sheep. Rape, which has a high water content, was mixed with yellow corn straw in various ratios to produce silage containing 50%, 55%, 60%, 65%, and 70% moisture; unmixed yellow corn straw was used as the control group. Samples underwent 60 days of in vitro fermentation in sealed containers containing rumen fluid from Tan sheep, with three repeats in each group, after which they were analyzed. The results showed that the dry matter digestibility (DMD) increased with the proportion of rape (P < 0.05); the lowest DMD was 48.01% in the control group, and the highest DMD was 66.81% in the 70% moisture group. There was no significant difference in neutral detergent fiber digestibility between groups ( P > 0.05). Gas production was significantly higher in the experimental groups than in the control group ( P < 0.05), but there was no significant difference among the five experimental groups ( P > 0.05). There were no significant differences between groups in terms of pH value, ammonia–nitrogen (NH 3-N) concentration, total volatile fatty acid concentration, or levels of acetic, propionic, butyric, isobutyric, or isovaleric acids (P > 0.05). In conclusion, the silage mix with 70% moisture content (79.45∶20.55 ratio of rape to corn straw) had the best effects on in vitro fermentation. However, the ideal proportion of rape to be included in mixed silage for Tan sheep needs to be determined using feeding experiments.
The effects of quinoa stalk on growth performance, nutrient utilization, and metabolism of Hu sheep lamb in fattening period were studied to determine its appropriate level in daily ration. Forty 3-month-old weaned male sheep with close average body weight were randomly divided into four treatment groups, each with 10 replicates of 1 sheep: control group, 8% quinoa stalk group, 16% quinoa stalk group, and 24% quinoa stalk group. The transition, pre-test, and trial periods were 14, 10, and 60 days, respectively. The results showed that body weight gain, average daily gain, organic matter intake and digestibility, and total digestible energy of sheep were improved with an increase in dietary quinoa straw level. The average daily gain, organic matter digestibility, and N digestibility, retention, and retention rate of the 16% quinoa stalk group were significantly higher than those of control group (P < 0.05), and its feed/weight ratio was significantly lower than that of control and 24% quinoa stalk groups ( P < 0.05). When the dietary quinoa stalk level was increased by 24%, the average daily gain of test sheep was significantly lower than that of the 16% group ( P < 0.05). Adding quinoa stalk to lamb diet could improve its growth performance and nutrient utilization rate, and the appropriate proportion recommended is 16%.
We investigated the effects of different levels of concentrate supplementation on the growth performance, blood markers, and economic return of yaks grazing in the warm season on the Qinghai-Tibet Plateau, aiming to provide a theoretical basis to guide the supplementary feeding of yaks. Forty-eight male yaks with good body condition and similar weight (123.96 ± 7.43 kg) were randomly divided into four groups (n = 12). The control group only grazed, while the three supplement groups received 0.5, 1.5, and 2.5 kg·d−1 of concentrate. The pre-test period was 10 days, and the formal experiment lasted 60 days. The supplementary feeding had a significant effect on the yaks’ average daily gain (ADG) (P < 0.05). The group receiving 2.5 kg·d −1 of supplement had the highest ADG (286.42% higher than the control group). Compared to the control group, the 1.5 and 2.5 kg·d−1 supplement groups had significantly higher glucose, total protein, and aspartate aminotransferase (P < 0.05) levels; however, urea nitrogen levels were significantly reduced in the 2.5 kg·d −1 supplement group (P < 0.05). 3) The supplement groups produced a greater economic return than did the control group, with that of the 2.5 kg·d −1 supplement group being the best. In conclusion, supplementary feeding increased the daily weight gain and economic return of yaks grazing in the warm season, with 2.5 kg of concentrate appearing to be the most appropriate amount to use in supplementary feeding.
Practical grazing strategies are fundamental for effective utilization of rangeland resources, but it remains debatable whether rotational grazing is superior to continuous grazing in terms of livestock production and grassland environment. By synthesizing the experimental evidence from 38 sites in arid and semi-arid grasslands in northern China and using the integrated analysis method to compare the effects of rotational grazing and continuous grazing on herbage yield, forage quality, and livestock weight, we found that rotational grazing was indeed more preferable than continuous grazing. However, rotational grazing was not practiced by herders in the arid and semi-arid grasslands of northern China because of some major drawbacks, such as overgrazing, a short growing season, frequent drought, and the relatively high costs. In general, we suggest that rotational grazing be promoted and optimized and that feasible practices, including controlling the grazing pressure, improving the rotational grazing income, and promoting a rotational grazing system based on the location and time, be followed in the arid and semi-arid grasslands of northern China.
The aim of this study was to establish a near-infrared prediction model for six nutrients of alfalfa hay using near-infrared reflectance spectroscopy (NIRS). In total, 200 samples of alfalfa hay were collected from five provinces (Gansu, Ningxia, Hebei, Jiangsu, and Shanxi) to analyze dry matter (DM), crude ash (Ash), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and ether extract (EE). The calibration and validation sets included 160 and 40 samples, respectively. The NIRS system was combined with modified partial least squares (MPLS) to construct and verify the prediction models. The results showed that the coefficient of determination for validation (RSQ) and ratio of performance to deviation for validation (RPD) of the DM prediction model of alfalfa hay were 0.87 and 2.67 and those of the NDF prediction model were 0.90 and 3.16, respectively. The constructed model can be used for prediction in actual production. The RSQ and RPD of the CP prediction model were 0.83 2.41 and those of the ADF prediction model were 0.82 and 2.28, respectively. The constructed prediction model cannot completely replace wet chemical analysis but can be used for the screening analysis of a large number of samples. The RSQ and RPD of the Ash content prediction model were 0.59 and 1.51, respectively. The constructed prediction model can only be used for a rough analysis. The RSQ and RPD of the EE content prediction model were 0.45 and 1.32, respectively. This constructed prediction model was poorly correlated and needed further optimization.
The Pratacultural Science, as a minor major related to agriculture science in Lanzhou University, needs to have positive changes to adapt to social development, especially under the background of constructing new agriculture science in the most of agricultural universities, thus to cultivate inter-disciplinary talents who can solve practical issues for our nation. Animal production course system is a very important part for Pratacultural Science, which is significance for students in this major to master basic knowledge of animal science, principle and technologies of animal production. Therefore, we summarized developmental history of Pratacultural Science and its curriculum system, and the current situation of animal production courses in the major of Pratacultural Science. Then we briefly analyzed and discussed our experiences that how we established animal production course system, including teaching team construction, curriculum provision of theory teaching and experiment training, improvement of teaching methods, guidance for undergraduates, innovation of course assessment. The purpose of above actions aims to supply references and suggestions for growing Pratacultural Science, and thus to cultivate more inter-disciplinary talents in Pratacultural Science and Animal Science in China.