Table of Content

20 December 2019, Volume 28 Issue 12

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Evaluation of grassland agricultural productivity by food equivalent unit

LOU Shan-ning, HOU Fu-jiang, REN Ji-zhou

2019, 28(12):  1-16.  DOI: 10.11686/cyxb2019079

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Building on the concept and definition of the Food Equivalent Unit, this paper modifies the original definition by including energy and protein digestibility for calculation of the forage food equivalent unit (FEU). Using 1 kg alfalfa as the forage standard (FEU=1.0 with standard edibility (100%), standard moisture content (10%), total energy (14.267 MJ·kg^-1), crude protein (229 g·kg^-1 DM), digestible DM (65.48%), feed standard energy and protein factors are derived and, together with digestibility values, used in the model to calculate FEU of other forage types. The FEU is proposed as a measure of the feed value of forage resources such as native grassland, cultivated forage, silage and cereal straw. The results indicate that the average FEU of all principal forage types in China is in the range of 0.2-1.2 FEU·kg^-1, and the FEU of leguminous forage (with good energy and protein content) is between 0.4-1.2 FEU·kg^-1. The FEU of Leucaena chinensis, of which the leaves have high digestibility, is 1.2 FEU·kg^-1; the FEU of grass species ranges from 0.2-1.0 FEU·kg^-1, with FEU of perennial ryegrass in the warm season being 1.0 FEU·kg^-1, and FEU of silage about 0.1-0.7 FEU·kg^-1. The FEU of straw is about 0.2 FEU·kg^-1. The FEU production capacity of 21 major natural grassland types (e.g.: desert steppe and alpine meadow) in summer growing season was calculated to be in the range 142-2739 FEU·ha^-1, with alpine meadow in Maqu, and Hebei’s meadow steppe grassland both being above 1300 FEU·ha^-1. The forage FEU has the potential to be used as a quick and easy-to-calculate-and-interpret measure of forage feed value of both arable and pastoral forage and feed crops, and as such, to be a valuable management tool in the selection of forage crops for livestock production.

Response to increasing precipitation in Artemisia desert grassland of soil seed bank composition and species diversity of germinating plants

TIAN Meng, SUN Zong-jiu, LI Ying, LI Pei-ying, XIE Kai-yun

2019, 28(12):  17-28.  DOI: 10.11686/cyxb2019288

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In this study, plots of six different precipitation regimes [natural conditions, CK; and artificially simulated precipitation increases of 5% (W₅), 10% (W₁₀), 15% (W₁₅), 20% (W₂₀) and 25% (W₂₅)] were established in moderately degraded Seriphidium transiliense desert grassland in order to study the effects of increasing precipitation on the seed density in the soil seed bank and on numbers of plant species represented. It was found that the number of species with germinated seedlings, and the seed numbers in the soil seed bank in the 0-5 cm soil layer increased gradually with increasing precipitation, with the germinated-seedling density of W₂₀ and W₂₅ being significantly (P<0.05) higher than other treatments, and the number of species with germinated seeds increased by 2.6 times and 2.0 times respectively as compared with the CK treatment (7 species). The same pattern was also seen in the seed bank of the 5-10 cm soil layer. For all six precipitation regimes, S. transiliense, Kochia prostrata and Gagea albertii all germinated in soil from the 0-10 cm soil layer, and precipitation increase significantly promoted the seed numbers germinated of S. transiliense, K. prostrata, Geranium transversale and Geranium albertii. With increasing precipitation, the Sorensen similarity between species germinating from the soil seed bank in the 0-5 cm soil layer and aboveground vegetation increased first and then decreased in S. transiliense desert grassland, and the Sorensen similarity of species composition of aboveground vegetation under W₂₀ and W₂₅ treatment was higher than other treatments. The Shannon-Wiener index, Pielou index and Patrick index of the number of species represented in the seedbank in S. transiliense desert grassland showed an increasing trend after precipitation enhancement, and the increase in the 0-5 cm soil layer was more obvious than that in the 5-10 cm soil layer. The germinated seed density in soil seed bank had obvious spatial heterogeneity, and was affected by the interaction of spatial sampling locations and precipitation. In summary, precipitation enhancement increased the number of germinating plant species, the density of seeds germinating, and the plant diversity index in the soil seed bank of the S. transiliense desert grassland studied. This in turn increased the similarity in species composition between the aboveground vegetation and the seedbank and was beneficial to the restoration of degraded sagebrush desert grassland.

Effects of nitrogen addition on ecological stoichiometric characteristics of carbon, nitrogen and phosphorus in Stipa baicalensis grassland soil aggregates

LI Ming, QIN Jie, HONG Yu, YANG Dian-lin, ZHOU Guang-fan, WANG Yu, WANG Li-juan

2019, 28(12):  29-40.  DOI: 10.11686/cyxb2019297

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The influence of atmospheric nitrogen deposition on grassland ecosystems is an important component process of global climate change, and therefore has become a research hotspot in ecology. Our study aimed to understand the influence of nitrogen deposition on the carbon (C), nitrogen (N) and phosphorus (P) ecological stoichiometric characteristics of grassland soil aggregates, in order to provide fundamental research data for the comprehensive analysis and assessment of the impact of nitrogen deposition on grassland ecosystems. Since 2010, six simulated nitrogen deposition field control experiments of N₀ (0 kg N·ha^-1·yr^-1), N₁₅ (15 kg N·ha^-1·yr^-1), N₃₀ (30 kg N·ha^-1·yr^-1), N₅₀ (50 kg N·ha^-1·yr^-1), N₁₀₀ (100 kg N·ha^-1·yr^-1) and N₁₅₀ (150 kg N·ha^-1·yr^-1) were set up in an area of typical Stipa baicalensis grassland in Inner Mongolia. It was found that nitrogen addition significantly (P<0.01) increased the stability of soil aggregates and the proportion of aggregates >2 mm in diameter. In addition, the organic carbon and total nitrogen contents of 0.25-2 mm aggregates were significantly (P<0.05) higher than those of other particle sizes, but the total phosphorus contents did not differ significantly with different particle sizes. Compared with the control group, nitrogen addition significantly (P<0.05) increased the organic carbon and total nitrogen content of soil macroaggregates >0.25 mm diameter, but had no significant effect on total phosphorus. Nitrogen addition reduced the C∶N ratio of >0.25 mm aggregates, but increased C∶P and N∶P ratios of 0.25-2 mm aggregates (P<0.05). A comprehensive analysis shows that nitrogen addition promotes the carbon sequestration potential of soil to a certain degree and increases the mineralization rate of organic matter in soil aggregates. With the increase of nitrogen addition level, the elemental P level in soil aggregates becomes the main limiting factor restricting the growth of grassland plants.

Development of a novel traffic simulator and evaluation of warm-season turfgrass traffic tolerance in field experiments

LIU Tian-zeng, WANG Xu-sheng, ZHANG Ju-ming

2019, 28(12):  41-52.  DOI: 10.11686/cyxb2019065

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A novel turf traffic simulator was developed in the present research to emulate traffic effects caused by players in football games. A field traffic experiment tested 20 turfgrass varieties and lines from the genera Cynodon, Paspalum, Zoysia and Eremochloa and the simulator was used to evaluate tolerance. After trampling, it was found that Zoysia and Eremochloa material retained better ground cover, turf color and root biomass than Cynodon and Paspalum. A total of 8 turfgrass varieties were selected from the 4 genera for further study. It was found that traffic tolerance of Tifgreen, Paspalum vaginatum cv. Sea Isle, Zoysia japonica cv. Lanyin No. 3 and Eremochloa ophiuroides cv. Huanan were superior to other varieties of the same genus. Among these four varieties, the only significant difference in leaf cellulose content observed was between Z. japonica cv. Lanyin No. 3 and Z. japonica cv. Qingdao (P<0.05), while lignin content showed no significant difference among the materials (P>0.05). The factors that enhanced the traffic tolerance in Z. japonica cv. Lanyin No. 3 and E. ophiuroides cv. Huanan were closely arranged cells, a thicker and continuous cuticle, more vesicular cells and a higher level of lignification. In Cynodon dactylon cultivars and P. vaginatum cv. Salam, a thin or absent cuticle, a lower level of lignification and fewer bulliform cells were associated with reduced traffic tolerance. Principal component analysis showed that ground cover, turf color and root biomass could be used as effective indicators in the evaluation of cultivar traffic tolerance. The results of this study will provide a methodology for the incorporation of testing for traffic tolerance in the development and utilization of warm-season turfgrass species.

Germination response to temperature of ten desert plant species

BAI Meng-jie, TAO Qi-bo, HAN Yun-hua, WANG Yan-rong

2019, 28(12):  53-62.  DOI: 10.11686/cyxb2019101

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Temperature is considered one of the most important environmental factors governing seed germination and seedling emergence. Therefore, knowledge of the seed germination response to temperature has is an important criterion when determining the appropriate planting time and predicting the seedling emergence of species in the field. Seeds of Ammopiptanthus mongolicus, Artemisia sphaerocephala, Astragalus adsurgens, Caragana intermedia, Caragana korshinskii, Cleistogenes songorica, Haloxylon ammodendron, Hedysarum fruticosum, Hedysarum scoparium and Zygophyllum xanthoxylum, were used in this study. The dynamics of seed germination were determined over a range of constant temperatures from 5 to 40 ℃ at 5 ℃ intervals. The temperature thresholds (Tb, To, Tc, θ_T) of ten desert plant species were calculated according to the thermal time model. The results showed that: in the test species, the optimum temperature (To) was 33.7 ℃ for C. songorica, 28.3 ℃ for A. mongolicus and for other species ranged from 17.4 to 24.9 ℃. The base temperature was 0.3 ℃ for A. adsurgens, followed by H. ammodendron at 1.9 ℃, with other species ranging between 6.7 and 15.0 ℃. The ceiling temperature was 45.3 ℃ for H. ammodendron, with C. songorica being 43.9 ℃, A. adsurgens 43.3 ℃, A. mongolicus 39.7 ℃, and the other species ranging from 25.0 to 34.2℃. The largest germination temperature ranges were 1.9 to 45.3 ℃ for H. ammodendron and 15.0 to 30.0 ℃ for Z. xanthoxylum. The thermal time requirement for germination, from lowest to highest, was: A. mongolicus (79 ℃·d), H. ammodendron (94 ℃·d), A. sphaerocephala (114 ℃·d), H. fruticosum (127 ℃·d), Z. xanthoxylum (132 ℃·d), H. scoparium (177℃·d), A. adsurgens (184 ℃·d), C. intermedia (217 ℃·d), C. korshinskii (302 ℃·d), C. songorica (334 ℃·d).

Effects of acid and cadmium stresses on seed germination, seedling growth, and submicroscopic structure of Pogonatherum crinitum

ZHAO Ya-man, CHEN Shun-yu, LI Zong-xun, LI Qi-yan, HOU Xiao-long, CAI Li-ping

2019, 28(12):  63-74.  DOI: 10.11686/cyxb2019280

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Pogonatherum crinitum can grow normally in mining areas with soil acidification and cadmium contamination. It may therefore be inferred that this plant species has special adaptations to soil acidity and cadmium stresses. Germination experiments with P. crinitum seed were carried out in an artificial climate chamber under different acidity (pH 5.5, 4.5, 3.5) and cadmium (5, 10, 20 mg·L^-1 Cd²⁺) stress treatments. Differences in seed germination, seedling growth, plasma membrane integrity of roots and submicroscopic structure of P. crinitum between different stress treatments were measured and compared. It was found acid stress improved the germination rate of the seeds, and there was no significant difference between acid stress treatments and the control for germination rate (P>0.05). The germination index of P. crinitum showed a gradual decreasing trend with decrease of pH. In the treatment pH 3.5, other germination indexes except for germination rate were significantly reduced compared with those of the Control (P<0.05). With increased Cd concentration, the seed germination and seedling growth gradually decreased and were eventually inhibited. However, the germination rate of seeds treated with 20 mg·L^-1 Cd was still greater than 40%. Analysis of correlation and membership functions indicated that when the pH value is greater than 3.5 and Cd concentration lower that 10 mg·L^-1, the seed germination and seedling growth will not be affected. However, with the decrease of pH value and the increase of Cd concentration, the seed germination and seedling growth were significantly inhibited, causing obvious damage to the plasmalemma of root tip cells and submicroscopic structure of buds, which resulted in rupture of organelle membranes and cell vacuolation. In summary, our results showed that seed germination and seedling growth of P. crinitum can be promoted by mild acid and cadmium stress and inversely inhibited by strong acid and Cd stresses.

Effects of manganese stress on seed germination, and seedling physiological and biochemical characteristics of Cleome viscosa

XIAO Ze-hua, LI Xin-hang, PAN Gao, WU Yao-wen, YANG Can-xin, KUANG Xue-shao, LIU Wen-sheng

2019, 28(12):  75-84.  DOI: 10.11686/cyxb2019041

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In order to investigate the resistance and physiological adaption mechanisms of Cleome viscosa to manganese (Mn) stress, the effects of different concentrations of Mn²⁺ (0, 1000, 5000, 10000, 15000 and 20000 μmol·L^-1) on seed germination, seedling growth and the changes in physiological and biochemical characteristics of C. viscosa after 7, 15 and 30 days of stress, were assessed. The results showed that: 1) With the increasing Mn²⁺ concentration, the germination potential, germination rate, germination index and vigor index of C. viscosa declined, although the seedling growth was increased at the 1000 and 5000 μmol·L^-1 Mn²⁺ concentrations, displaying a phenomenon of “low to promote and high inhibition”. 2) Compared with the control, chlorophyll a, chlorophyll b, chlorophyll a+b content and the ratio of chlorophyll a∶b increased at the Mn²⁺ concentrations of 1000 and 5000 μmol·L^-1, while the chlorophyll content and the ratio of chlorophyll a∶b decreased with rising of Mn²⁺ concentration above 5000 μmol·L^-1 and with exposure time. 3) Under Mn²⁺ stress at day 7, superoxide dismutase (SOD) activity decreased with rising Mn²⁺ concentration, while the activities of peroxidase (POD) and catalase (CAT) increased; Under Mn²⁺ stress at day 30, the activities of SOD and POD decreased, while the activity of CAT didn’t decline. 4) Proline, soluble protein and soluble sugar of seedlings increased significantly with rising Mn²⁺ concentration at day 7 and day 15 of exposure, but had decreased after 30 days of stress. 5) Malondialdehyde content increased significantly with increasing of Mn²⁺ concentration and exposure time. In summary, the results showed that exposure to Mn²⁺ concentrations of 1000 and 5000 μmol·L^-1 promoted seedling growth of C. viscosa, and at higher Mn²⁺ concentrations this plant species can adjust its antioxidant system and enhance its osmotic adjustment to alleviate the damage caused by high Mn stress, thus imparting C. viscosa with a measure of Mn tolerance.

Effects of exogenous mannose application on drought tolerance, sugars, and sugar alcohol accumulation in white clover

LI Zhou, PENG Yan, YIN Shu-xia, HAN Lie-bao

2019, 28(12):  85-93.  DOI: 10.11686/cyxb2019042

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Effects of exogenous application of mannose on water status, osmotic adjustment, antioxidant capacity, photosynthetic response, sugars, and sugar alcohol accumulation in ‘Ladino’ white clover were studied under drought stress using physiological analysis and gas chromatography-mass spectrometer (GC-MS) technology. Results showed that drought stress significantly decreased relative water content, chlorophyll content, photochemical efficiency (F_v/F_m), and net photosynthesis rate resulting in membrane lipid peroxidation and decrease in cell membrane stability in leaves of white clover. However, white clover improved water use efficiency and decreased osmotic potential in order to acclimate to drought stress. The application of exogenous mannose (30 mmol·L^-1) significantly increased photosynthesis, total antioxidant capacity, and osmotic adjustment, thereby alleviating drought-induced oxidative damage and maintaining better water balance during drought stress. GC-MS analysis showed that drought stress induced differential changes of many sugars and sugar alcohols in leaves of white clover. Exogenous mannose application enhanced the accumulation of many sugars (mannose, glucose, fructose, galactose, xylose, sucrose, maltose, and trehalose) and sugar alcohols (myo-inositol, glycerol, and D-pinitol) in white clover under drought stress contributing to improved osmotic adjustment and energy supply for the maintenance of growth.

Cloning and function analysis in tobacco of MsZAT10 from alfalfa

SUN Ya-nan, LIN Ru, PAN Xiao-yang, CHEN Yue, TAO Lei, GUO Chang-hong

2019, 28(12):  94-102.  DOI: 10.11686/cyxb2019045

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C2H2 type zinc-finger proteins (ZFPs) play important roles in abiotic stress response in plants. In this study, a novel C2H2 ZFP family gene, MsZAT10, from alfalfa (Medicago sativa), was cloned and characterized. The full length coding sequence (CDS) of MsZAT10 is 762 bp, and encodes a protein of 253 amino acids containing two conserved single C2H2 domains and a typical QALGGH conserved motif. Phylogenetic analysis showed that MsZAT10 shared sequence similarities of 76% with MtZAT10 [the closet homologous gene in Medicago truncatula (XP_003592502.1)]. The plant expression vector pCBM::MsZAT10 was constructed and inserted into tobacco by Agrobacturium-mediated transformation. Twenty-five positive transgenic lines were obtained, verified from a phosphinothricin screen and PCR identification. The MsZAT10 gene was expressed in transgenic lines confirmed by qRT-PCR analysis, and three transgenic lines were selected for further study. Transgenic tobacco plants showed higher tolerance and lower relative conductivity than those of wild type tobacco after exposure to a -4 ℃ temperature for 2 h. The tissue proline and soluble protein concentrations in transgenic tobacco were higher than those in wild type tobacco exposed to 0 ℃ for 5 h. In contrast, malondialdehyde levels were lower than those in wild type tobacco. After treatment with 300 mmol·L^-1 NaCl for 4 days, the leaf discs remained green in transgenic tobacco while the wild type tobacco turned chlorotic. These results indicated that overexpression of MsZAT10 enhanced plant tolerance to low temperature and salt stress in transgenic tobacco.

Effects of AM fungus and grass endophyte on the infection of Lolium perenne by the pathogen Bipolaris sorokinianum in a greenhouse

DENG Jie, LI Fang, DUAN Ting-yu

2019, 28(12):  103-113.  DOI: 10.11686/cyxb2019104

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In a greenhouse, perennial ryegrass seeds infected with (E+) and without (E-) grass endophyte and pot culture inoculated with (AM) or without (NM) the arbuscular mycorrhizal fungus Rhizophagus intraradices were used as the grass endophyte and AM treatments. The pathogen Bipolaris sorokiniana was inoculated six weeks after seedling emergence by spraying onto leaves and pouring onto soil for root infection, and the same amount of distilled water was applied to non-inoculated (B-) treatments. Two weeks after pathogen inoculation, disease incidence, AM colonization, chlorophyll content, photosynthetic indexes and P content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) and H₂O₂ concentration of the perennial ryegrass host plants were measured to determine the growth, physiological and biochemical impacts of the pathogen on perennial ryegrass. It was found that the disease incidence of perennial ryegrass inoculated with pathogen ranged from 2.50%-31.25% in leaves. Both AM fungus and grass endophyte reduced the disease incidence, and also promoted P absorption and photosynthesis, and increased the biomass accumulation to some degree. Compared with control treatments, infected with grass endophyte and inoculated with AM fungus decreased disease incidence of perennial ryegrass that inoculated with pathogen in leaves by 32.00%-92.00%. In the all treatments with plants that were infected by pathogen in leaves and roots; the co-colonization of AM fungus and grass endophyte increased net photosynthetic rate, stomatal conductance, chlorophyll content, total P content and SOD enzyme activity by 132.25% and 132.17%, 56.00% and 134.48%, 37.69% and 40.77%, 41.51% and 38.17%, 95.65% and 11.72% (P<0.05), as well as decreased MDA and H₂O₂ concentration by 31.36% and 24.45%, 58.62% and 22.22%, respectively. These results showed that AM fungi and grass endophyte can promote plant growth and improve plant resistance to disease, and the combination of both the symbiont microorganisms provided the greatest benefit.

Effects of tannins in banana leaves on in situ digestion in dairy cows

LI Zhi-wei, ZHAO Jing-wen, SHEN Si-cong, LUO Jia-xuan, ZHAO Guo-qi, HUANG Qian-qian

2019, 28(12):  114-123.  DOI: 10.11686/cyxb2019375

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The purpose of this study was to investigate the effects of tannin from banana leaves on the rumen degradation characteristics in dairy cows and to evaluate the feeding value of banana leaves. The treatments comprised alfalfa (100% alfalfa), alfalfa and banana leaf mixed (50% alfalfa+50% banana leaves), banana leaf (100% banana leaves), alfalfa with polyethylene glycol (PEG) (alfalfa+6% PEG), alfalfa and banana leaf mixed with PEG (alfalfa+banana leaves in a 1∶1 mixture+6% PEG), banana leaf group with PEG (banana leaves+6% PEG). In situ dry matter (DM), neutral detergent fiber (NDF) and crude protein (CP) degradability were determined by incubating the conserved forages in 3 rumen cannulated Holstein cows for 0, 2, 4, 8, 12, 24, 48 and 72 h. The results indicated that compared to alfalfa, banana leaves had lower rapidly degraded fraction (a), slowly degraded fraction (b), fractional disappearance rate (c) and effective degradability (ED, P<0.001) of DM and CP. However, the ED of NDF was similar for alfalfa and banana leaves. Both banana leaves and the alfalfa-banana leaf mixed forage with PEG had greater slowly degraded fractions and ED of DM, NDF and CP, than the two groups without PEG (P<0.001). In summary, the results indicated that tannins in banana leaves inhibited ruminal degradation of the banana leaves, and thus their level of inclusion in mixed diets needs to be controlled when fed to ruminants.

Effects of whole corn silage, millet straw and Leymus chinensis combined in total mixed ration fed Holstein cows in the early dry period on its performance and blood biochemical and immune indicators inperinatal period

REN Wei-zhong, GAO Yan-xia, LI Qiu-feng, CAO Yu-feng, LI Jian-guo

2019, 28(12):  124-136.  DOI: 10.11686/cyxb2019068

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The purpose of this study was to investigate the effects on cow performance and blood biochemical and immune indicators in the perinatal period, of different proportions of millet straw and Leymus chinensis, added to a constant base of 16% concentrate and 24% whole-plant maize silage in a total mixed ration (TMR) diet fed to Holstein cows in the early dry period. Forty-five Holstein cows with similar body weight, parity, body condition and calving date in the early dry period were selected and randomly divided into 3 groups: A, B and C, fed with a TMR diet comprising concentrate, whole-plant corn silage, millet straw and L. chinensis in ratios of 16∶24∶30∶30, 16∶24∶45∶15 and 16∶24∶60∶0, respectively. The three groups of cows were transferred to a perinatal herd two weeks before calving, and after transfer were fed the same diets in the pre-perinatal and post-perinatal period. The whole trial lasted for 88 days. The results showed that: 1) Compared with group C, the dry matter intake (DMI) of group B was increased by 10.46% (P<0.05), 7.79% (P<0.05) and 5.65% (P<0.05), respectively, at week 1, week 2 and week 3 postpartum. In addition, at 1 week postpartum, the body condition scoring of cows in group B was 6.60% higher than that of group C (P<0.05), while at 2 and 3 weeks postpartum BCS was 9.06% higher (P<0.05). 2) There was no significant difference between the 3 test groups (P>0.05) in the birth weight of calves. The Immunoglobulin (Ig) G content of colostrum in group A and B was, respectively 10.82% (P<0.01) and 18.07% (P<0.01) higher than that in group C. 3) Compared with group C, the milk yield of group B was increased by 9.00% (P<0.05), the non-fat solid content by 2.83% (P<0.05), the milk protein content by 10.59% (P<0.05) and the lactose content by 5.64% (P<0.05). However, there was no significant difference in milk fat percentage and milk urea nitrogen among the test groups (P>0.05). 4) On the day of delivery and 21 days after delivery, the serum triglyceride levels of group B cows were significantly lower than those of groups A and C (P<0.05), the blood glucose levels of group B were significantly higher than that of group A and group C (P<0.05), and serum urea nitrogen and insulin levels in group B were significantly lower than those in group C (P<0.05). Also, insulin-like growth factor and total protein levels in group B cows were significantly higher than those in group C (P<0.05). At 7 days before delivery and on the day of calving, serum IgA, IgM and IgG in group B cows were significantly higher than those in group C (P<0.05). At 21 days postpartum, serum IgM and IgG levels in group B cows were significantly higher than those in group C (P<0.05). At day 7 before and on the day of calving, leptin levels of group B cows were significantly higher than group C cows, while the serum non-esterified fatty acid level of group B was significantly lower than that of group C (P<0.05). At day 7 before calving, on the day of calving and at day 21 after the calving, the cholesterol levels of group B cows were significantly lower than those of group C (P<0.05), while the serum albumin levels of group C cows were significantly higher than for group C, and the AST and ALT levels of group B were significantly lower than those of group C (P<0.05). There was no significant difference in β-hydroxybutyric acid between the test groups (P>0.05). In summary, the diet composition and nutrient level in the early dry period affected cow body metabolism and production performance in the perinatal period. Under the conditions of this experiment, the optimal TMR formulation for Holstein cow diet in the early dry period was a mix of concentrate, whole plant corn silage, millet straw and L. chinensis in the ratio 16∶24∶45∶15.

Effects of cutting date and crop growth stage on alfalfa silage quality

LI Fei-fei, ZHANG Fan-fan, WANG Xu-zhe, TANG Kai-ting, MA Chun-hui

2019, 28(12):  137-148.  DOI: 10.11686/cyxb2019111

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This study evaluated the effect of the cutting date and growth stage at cutting on nutritional quality and fermentation characteristics of alfalfa of [147 regiment] in Shihezi city, Xinjiang. Data were collected for the first, second and third cuts of the season, for bud, early flowering, and flowering crop growth stages. Silage quality was determined by sampling at 3, 9, 15, 30, 45 and 60 days after commencement of silage fermentation. Highly significant (P<0.01) effects of cutting date on crop growth duration, dry matter yield, neutral detergent fiber, crude protein, lactic acid and acetic acid contents of silage were observed. In alfalfa the silage fermentation process can reduce nutrient content. After 60 days fermentation, DM content of alfalfa silage in the third cutting was the highest, reaching 39.03%. Acid and neutral detergent fiber contents were lowest in the third cut at the budding crop growth stage, while crude protein contents were highest in the first cut at budding stage. CP and WSC were the highest in the first cutting, which was 20.21% and 4.39%, respectively. The highest silage lactic and acetic acid contents occurred in second cut silage harvest at the budding stage. The ammonia nitrogen content of silage from the first cut was the lowest at the budding stage. The earlier the cutting time, the more tender the alfalfa crop was, and the higher the nutritive quality and palatability was, and plant regrowth was also improved. The overall ranking of cut and growth stage combinations for silage nutritive value, quality and yield was: first cut at bud stage>third cut at bud stage>first cut at early flowering stage>second cut at bud stage>third cut at early flowering stage>first cut at flowering stage>third cut at flowering stage>second cut at early flowering stage>second cut at flowering stage. Therefore, controlling the cutting time of alfalfa could improve the nutrition, fermentation quality and utilization rate of alfalfa.

Evaluation of agronomic and forage quality traits of a range of oat cultivars

WANG Qian, LI Zhi-jian, LI Jing, ZHOU Bang-wei

2019, 28(12):  149-158.  DOI: 10.11686/cyxb2019040

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Seven Avena nuda and thirteen Avena sativa cultivars were evaluated in western Jilin Province of China to compare forage yield, grain yield, and the main agronomic and forage quality traits. The data analysis combined the techniques of gray correlation and cluster analysis to identify the agronomic and nutritional quality traits which best predict high yield and forage quality in an oat cultivar. The results showed that forage yield at heading and anthesis stages and the grain yield at maturity of A. sativa were superior to that of A. nuda, however, A. sativa had higher acid and neutral detergent fiber concentrations which decreased its forage quality. Although there was no difference in crude protein (CP) content between A. nuda and A. sativa, the rapid decline in CP after flowering indicated the forage quality would have been significantly reduced during crop maturation. For A. sativa, the forage yield was negatively correlated with grain yield and CP, which indicated there were trade-off relationships between high grain yield and high forage quality. However, this did not apply to A. nuda. According to the integrative analysis of agronomic and forage quality traits at the grain filling stage, the cultivars A. sativa Tianyan No.1 and A. nuda Baiyan 16 were the best performing forage oat cultivars, and could be widely planted for forage in this region.

The seasonal nutritional dynamics of major forages composition of the steppe of Bahrain Right Banner and its forming structure of the saturated chain alkane research

LI Bao-dong, DENG Yu, SUN Hai-zhou, ZHAO Rui-xia, SA Qi-reng-gui, LI Xiao-yan, HONG Min, SANG Dan, ZHANG Chun-hua, REN Xiao-ping

2019, 28(12):  159-168.  DOI: 10.11686/cyxb2019067

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Seven conventional nutrient analyses were conducted monthly for 10 forage species in the typical steppe grassland of Bahrain Right Banner from May to the following January, and concentrations of 8 saturated chain alkane compounds from eight of the forage species were measured in July and October, to study the seasonal changes in grassland feed quality. It was found that across the May-January period studied, crude protein (CP) content decreased significantly (P<0.05) quarter by quarter, in most of the species measured. The calcium content peaked (P<0.01) in October, and total P (TP) content was highest (P<0.01) in May. The acid detergent fiber (ADF) content was highly correlated with the neutral detergent fiber content (NDF) (P<0.01), while Ca content displayed an extremely negative correlation with TP content (P<0.01). In July and October, the concentrations of C₂₉ and C₃₁ saturated chain alkanes were much higher (P<0.01) in most grass samples, than the other six saturated chain alkanes measured. On principal component analysis of the data, Z₁ and Z₂ which were the principal component scores reflecting the saturated chain alkane composition were significantly different (P<0.05). For the major forage species in the steppe grassland of Bahrain Right Banner, the above data showed that supplementary feeding would be required by livestock as the CP decreased in late season, seasonal trends in herbage calcium and phosphorus contents were opposite, and the nutritional value of herbage for grazing livestock could also be estimated by the paraffin determinations as the contents of the various saturated chain alkanes in these forages showed seasonal variation parallel to that of the nutritional parameters.

Research advances in Fusarium root rot of alfalfa (Medicago sativa)

FANG Xiang-ling, ZHANG Cai-xia, NAN Zhi-biao

2019, 28(12):  169-183.  DOI: 10.11686/cyxb2019105

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Alfalfa (Medicago sativa) has the largest sown area and is the most important forage crop in China and internationally. Root rot disease caused by Fusarium spp. (Fusarium root rot) is one of the major constraints for alfalfa production, and influences the yield and quality of this crop, resulting in the decline and shortened-unitlization life of grassland. Fusarium spp., being one of the most important soil-borne fungal pathogen groups, account for much current reasearch into root rot of alfalfa. Since Fusarium spp. can survive in soil for long periods and alfalfa is a perennial forage, it is particularly difficult to control Fusarium root rot in alfalfa. Research advances in Fusarium root rot of alfalfa in relation to the distribution and damage, pathogen species and biological characteristics, infection sources and occurrence regularity, pathogenicity and pathogenicity mechanisms, cultivar resistance and control methods are summarized and discussed. Finally, future research directions are proposed. This effort should provide theoretical directions for future research as well as the development and implementation of new methods for disease control.

Application of RNA-seq technology in research on herb, shrub and tree stress resistance

GAO Hui-juan, LÜ Xin-pei, WANG Run-juan, REN Wei, CHENG Ji-nan, WANG Yong-ping, SHAO Kun-zhong, ZHANG Jin-lin

2019, 28(12):  184-196.  DOI: 10.11686/cyxb2019352

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Biotic and abiotic stresses pose a great threat to crop yields and ecological environment conservation. As herbs, shrubs and trees are extremely adaptable to the external environment, it has become a current trend to identify the stress-tolerant genes and investigate the adaptive mechanisms of herbs, shrubs and trees. Research on molecular mechanisms of plant resistance to stress, using sequencing technology, has become a major part of the investigation of plant stress physiology. As biotechnology has developed, the transcriptome approach (RNA-seq) has emerged as one of the crucial approaches for identification of stress-tolerant genes. The next-generation sequencing technologies (NGS) are low cost and have greater depth than ever before. These include Roche/454, Illumina/Solexa, and ABI/Solid, and have been widely applied to whole-genome, RNA-seq and miRNA sequencing studies. Therefore, RNA-seq has high potential to accelerate the elucidation of the molecular mechanisms of herb, shrub and tree resistance and thus for identification of a large resource of gene sequence information. Such research will lay a solid foundation for developing stress-tolerant crops, herbs, shrubs and tree species. Research examples of the biotic and abiotic stress-tolerance of herbs, shrubs and trees identified using RNA-seq are introduced in this paper. The emerging trends and prospects for further applications of RNA-seq are also discussed.

A ‘denitrification-decomposition’ (DNDC) model evaluation of alpine meadow soil carbon response to climate change

WANG Duo-bin, JI Chang-ting, LIN Hui-long

2019, 28(12):  197-204.  DOI: 10.11686/cyxb2019081

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It has been demonstrated that climate change and associated warming has affected the soil organic carbon (SOC) in alpine meadows over past decades, but little is known about the coupling between climate change and grazing. In this research, an experiment incorporating controlled warming and grazing was used in conjunction with a denitrification-decomposition (DNDC) model to evaluate the contributions of climate change and grazing to changes in SOC in an alpine meadow ecosystem on the Tibetan Plateau. It was found that climate change influenced SOC negatively; while grazing intensity was an external factor that further modified SOC through trampling, defoliation and manure return. The model explained 63.4% of the observed change in SOC. Specifically, climate change (temperature and precipitation) was the major factor affecting SOC, and explained 61.9% of the variation in SOC. By contrast, grazing intensity explained 1.6% of the variation in SOC. These findings show that ongoing climate change and grazing can be expected to reduce SOC in alpine meadow ecosystems, potentially hindering their ability to provide ecosystem functions and services for human well being. Grassland ecosystem management should consider potential climate change effects to achieve sustainable development in this region.

Effects of additives on the quality of mixed silage of amaranth and soybean meal

LI Shun, MU Lin, ZENG Ning-bo, CHEN Dong, ZHANG Zhi-fei, YE Zhi-gang

2019, 28(12):  205-210.  DOI: 10.11686/cyxb2019043

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The effects of different additives on the quality of mixed silage of amaranth and soybean meal were investigated. Amaranth and soybean meal mixed in a 72%∶28% ratio were used as the silage substrate with seven different additive treatments: molasses, lactic acid bacteria, cellulose complex enzyme, molasses and lactic acid bacteria, molasses and cellulose complex enzyme, lactic acid bacteria and cellulose complex enzyme, molasses and lactic acid bacteria and cellulose complex enzyme, together with a control treatment where an equal amount of water to the additive treatments was applied. After being ensiled for 30 days, the samples were opened and analyzed. It was found that the fermentation quality and nutritional quality of the mixed whole amaranth-soybean meal silages were improved compared to control, when the additives molasses, molasses and lactic acid bacteria, molasses and cellulose complex enzyme or molasses and lactic acid bacteria and cellulose complex enzyme were used. The pH value, dry matter loss, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) levels were significantly (P<0.05) reduced with these additives, and the water-soluble carbohydrate (WSC) content and relative feed value (RFV) were significantly improved (P<0.05). The treatments incorporating lactic acid bacteria, cellulose complex enzyme or lactic acid bacteria and cellulose complex enzyme were not ideal, and their pH value, and NDF and ADF content were all higher than the control group (P<0.05). Considering all the data, addition of molasses or molasses and lactic acid bacteria or molasses and cellulose complex enzyme to mixed whole amaranth and soybean meal silage is suggested as optimal.

Effects of silage additives on nutritional quality and silage quality of triticale and rye

DAI Han-ling, TIAN Xin-hui, DU Wen-hua, WU Jian-ping

2019, 28(12):  211-219.  DOI: 10.11686/cyxb2019044

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This research studied the effect of formic acid and two kinds of lactobacillus additive (Sila-Max, Sila-Mix) on the quality and nutrient composition of rye and triticale silage. The experiment used a two-factor design (2 plant species; 4 silage types, the three additives as above and an untreated control). It was found that neutral and acid detergent fiber (NDF and ADF, respectively) contents in the formic acid treatment group were significantly lower than other treatments (P<0.05), while water soluble carbohydrate (WSC) content and dry matter digestibility (DMD) were significantly higher than in the control (P<0.05), and the silage nutrition quality was the best. The DMD and lactic acid contents of the Sila-Max and Sila-Mix treatment groups were significantly higher than those of the other treatment groups (P<0.05), pH value, while NH₃-N:TN were significantly lower than the control group (P<0.05). The silage nutrient quality and fermentation quality of treated silages were better than the control group. Among the treatments, Sila-Max required the lowest dosage of additive, and resulted in the best silage fermentation quality. Compared with rye silage, triticale silage had superior nutritive quality and silage quality. Triticale was more suitable for the use of silage. In summary, the best silage nutritional quality was obtained with triticale treated with formic acid, and the best silage quality was obtained with triticale treated with Sila-Max.