Grassland Science最新文献

This study aimed to determine the fermentation quality, nutritive value and in vitro ruminal digestion of silages produced with mixtures of Napier grass (NG) and sugarcane top (ST) in five different ratios of fresh matter: 100:0 (N100), 75:25 (N75), 50:50 (N50), 25:75 (N25) and 0:100 (N0) with or without lactic acid bacteria (LAB) and formic acid (FA). The NG contained a higher crude protein (CP) content and buffering capacity, but lower dry matter (DM), organic matter, neutral detergent fiber, acid detergent fiber and water-soluble carbohydrates contents than ST. The N25 silage fermented well, with a significantly higher lactic acid (LA) content (p < .05) and lower pH and NH₃-N concentration than those of other mixed silages (p < .05). The FA addition resulted in the highest CP content and lowest pH, LA, acetic acid (AA) and NH₃-N contents, while LAB addition resulted in the highest LA content compared with other treatments. Although in vitro DM digestibility (IVDMD) did not significantly differ among the mixed silages (p > .05), mixing with ST and adding LAB or FA increased the IVDMD. Gas production (GP) and AA content of N25 silages were significantly higher than those of other silages (p < .05). The LAB- or FA-treated silages had higher IVDMD, GP, total volatile fatty acid and AA contents (p < .05) but lower pH compared with the control silage (p < .05). These results demonstrated that NG utilization improved upon mixing with ST due to the enhanced fermentation during ensiling, and the optimum mixing ratio for NG and ST was 25:75 on FM basis. Using LAB and FA as additives during ensiling can improve silage fermentation quality and in vitro ruminal digestion.

Satisfying the animals feed demand from the forage supply by grasslands remains a major challenge in the grassland–livestock ecosystem. To provide an alternative forage sources, this study conducted two feeding trials in the summer of 2015 and 2016 to compare the nutritive value, digestibility and nutrients utilization of native pasture (NH) and oat forage (OT) fed to Tibetan sheep (Ovis aries). Twelve Tibetan sheep with a mean body weight of 39.11 ± 3.66 kg in 2015 and 27.97 ± 2.69 kg in 2016 were use in this study. The experiment was 2 (year: 2015 and 2016) by 2 (forage: NH and OT) factorial. Data on proximate analysis, fiber fraction and nutrients digestibility were collected and analyzed using general linear model. However, the crude protein (CP) and water-soluble carbohydrates contents in OT were higher (P < .001) than those in NH by 7.81–8.93% and 46.40–47.05%, respectively. In contrast, the neutral detergent fiber (NDF) and acid detergent fiber contents were higher (P < .001) in NH by 14.28–15.78% and 15.62–18.00%, respectively. The dry matter digestibility coefficient in OT (0.82 in 2015 and 0.79 in 2016) was significantly higher than that in NH (0.68 in both years). In addition, the OT diet had higher (P < .001) organic matter, NDF and CP digestibilities. Animals fed OT retained significantly more nitrogen (2.66 g/day in 2015 and 1.93 g/day in 2016) than those fed NH (0.96 g/day in 2015 and 0.42 g/day in 2016). The digestible energy and metabolizable energy were higher (P < .001) in OT than in NH. Our data indicated that Tibetan sheep urinary N excretion increased by 0.726 g with increase of 1 g in the nitrogen intake. Conclusively, the OT had higher nutritive value than NH and could therefore use to satisfy livestock demand and reduce the grazing pressure on grasslands.

Italian ryegrass (Lolium multiflorum Lam.) cultivars vary widely in their persistence; there are very early heading annual types as well as very late heading, summer-survival types that survive for 2 or 3 years. Hybrid cultivars that survive in summer temperatures are bred using genes of a similar species (Festuca) in combination with Lolium. It is hypothesized that commercial summer-survival cultivars of Italian ryegrass include Festuca genome fragments. In this report, we investigated the genomic constitution of five summer-survival cultivars using the genomic in situ hybridization technique. Two out of the five cultivars contained Festuca genome fragments, confirming that summer-survival cultivars may include Festuca genome fragments.

Identifying grass species in grasslands based on unmanned aerial vehicle hyperspectral remote sensing is the basis and premise of hyperspectral remote sensing when applied to grassland degradation monitoring and research. The small targets and mixed pixels involved grass species identification in grasslands creates problems, making identification cumbersome and classification accuracy difficult. This study involved the construction of an unmanned aerial vehicle hyperspectral remote sensing system using hyperspectral data of grass species in desert habitats that had been collected under natural light. A multi-resolution combined with a 1 × 1 feature map was formed by multiscale convolution, and grass species data were extracted from hyperspectral fine-grained feature data from grasslands. A recognition and classification model for degradation indicator species CNN was constructed using max pooling to retain the maximum amount of feature detail and up-sampling, reconstructing the feature space and feature fusion to smooth the edge texture of the data and enhance the weak data to alleviate the imbalance among samples. The results showed that the overall identification accuracy of the model for grassland species reached 98.78%, and the kappa coefficient reached 0.92, realizing the high-precision identification of grassland species, which laid the foundation for grassland species detection and research based on unmanned aerial vehicle hyperspectral imagery. In addition, the proposed degradation indicator species CNN model provides a useful reference for the identification and classification of small targets with mixed pixels.

The study aimed to determine the effect of fumaric and maleic acids on the ensiling process. The corn herbage was ensiled without additives (control silage) or with 0.25% fumaric acid (FA25), 0.50% fumaric acid (FA50), 0.25% maleic acid (MA25), 0.50% maleic acid (MA50), FA25 + MA25 (FA25MA25) and FA50 + MA50 (FA50MA50) (treatment silages) as wet basis. The starch contents of FA50 and MA50 silages were lower than the content of the control silage (p < .05). The lactic acid content of the FA50MA50 silage was lower than that of the control silage (p < .05). Percentages of linoleic acid of MA25 and MA50 silages were higher than that of the FA50 silage (p < .05). The in vitro methane production and metabolic energy (ME) value of FA50MA50 silage was lower than that of the control silage (p < .05). The in vitro organic matter digestion (OMD) values of FA25, MA25 and FA50MA50 silages were lower than that of control silage (p < .05). The molarities of acetic (AA), propionic (PA), butyric (BA), isovaleric (IVA), isobutyric (IBA) and total volatile fatty (TVFA) acids of the in vitro ruminal fermentation fluid for the FA50MA50 silage were lower than that of the control silage (p < .05). As a result, the addition of fumaric and maleic acids (0.25% alone and together, or 0.5% alone) in ensiling of corn herbage did not change the quality, acidity (except for propionic, butyric and isobutyric acids) and nutrient contents (except for non-fiber carbohydrates and starch) and in vitro ruminal fermentation values (gas–methane production and organic acids). The combined use of 0.5% fumaric plus 0.5% maleic acid harmed silage quality and in vitro ruminal fermentation values. However, 0.5% maleic acid was partially more effective than those other organic acid additions in preserving linoleic and α-linolenic acids in the silage material.

The addition of self-regenerating annual legumes into permanent pastures can benefit rapid forage growth in early spring, leading to increased pasture production and animal live weight gain (LWG). The objective of this 2-year grazing study was to evaluate the effects of balansa clover (Trifolium michelianum) and subterranean clover (Trifolium subterraneum) on pasture and animal production in an irrigated dairy system in western Oregon, USA. Study results showed that balansa clover has a high potential to increase legume content of establishing pastures in early spring. Legume content of pastures sown with annual legumes increased by 25.3% in early spring compared to pastures sown without annual legumes. However, no significant increase in legume content was observed past the initial year of establishment. The persistence of balansa clover and subterranean clover was low in 2021, at <1% of the botanical composition. The overall benefits of balansa clover in early spring in 2020 were offset by reduced perennial forbs, white clover (Trifolium repens) and chicory (Cichorium intybus), in paddocks that were sown with annual legumes. However, this did not negatively affect the LWGs of heifers. This study found no significant difference between pastures sown with and without annual clovers pastures on dry matter production and animal production. Balansa clover was competitive in the establishment year; however, further research into improving its persistence past establishment is warranted.

Foliar spraying of selenium (Se) during the wheat grain filling period can effectively increase grain Se concentration. However, it is unclear when foliar spraying Se can efficiently increase grain Se concentration. In this study, 0, 18.90, 37.80 and 56.70 g/ha of selenate were sprayed on the leaf blades on the 2nd and 9th day after grain filling, respectively, to investigate the effect of different spraying time points on Se concentration in aerial parts, especially the grains. The results indicated that Se concentrations in aerial parts increased with selenate levels at different time points. On the 7th day after spraying Se, Se concentrations in leaf blades, leaf sheaths, nodes, internodes and cobs sprayed with Se on the 2nd day after grain filling were significantly higher than those in corresponding parts sprayed with Se on the 9th day (p < 0.05). However, the Se concentrations of aerial parts on the 14th day after spraying Se and at grain maturity on the 2nd day after grain filling were significantly lower than those on the 7th day after spraying Se on the 9th day (p < 0.05). Furthermore, on the 7th day and 14th day after spraying Se and at grain maturity, grain Se concentrations sprayed with Se on the 2nd day after grain filling were significantly lower than those sprayed with Se on the 9th day (p < 0.05). These results suggested that spraying Se on the 9th day after grain filling was beneficial for increasing the Se concentration in aerial parts, especially grains. This study provides a theoretical basis for efficiently enhancing grain Se concentration and producing Se-enriched bran and straw, which is of great significance for improving Se intake of livestock, enhancing livestock immunity, and promoting the development of animal husbandry.

The body mass of small mammals is widely regarded as an indicator of habitat quality, with trade-offs between anti-predator and energy-building behaviors noted across many species and habitat conditions as suggested by optimal foraging theory. In this study, however, grazing by domestic yak was noted to mediate this effect, affecting both the body mass and behaviors of plateau pika, Ochotona curzoniae, which deviated from expected ecological patterns. Specifically, we compared conditions of plateau pika at 16 trap sites across a range of habitats on the Tibetan plateau, each characterized by herders according to their seasonal use as winter, spring, or summer pastures, and to their vegetative conditions. Plateau pika body mass at herders' tent sites where female and young domestic yak sleep was about 6% higher than at yak foraging sites and 10% higher than fenced areas (where yak are excluded) despite the additional disturbance encountered at tent sites. Mean body mass of plateau pika also decreased with increasing slope, and adult body mass was lower in spring compared to winter and summer seasons. Furthermore, more pika burrows were found near herders' tent sites, with burrows exhibiting significantly lower vegetation cover. Pika foraging behavior was most frequent in yak bedding areas (near herders' tent sites), and pika vigilant behavior at yak foraging areas. Recalling that foraging and vigilant (predator avoidance) behaviors constitute energy trade-offs, we speculate that these unexpected findings may result from the combined effects of soil erosion (due to surface disturbances) and fertilization (with yak dung) at yak resting sites, which could enable higher population densities and body masses of plateau pika despite lower vegetation cover at the tent sites – most likely due to critical behavioral adaptations, ecological dynamics such as predator-prey relations and other multi-dimensional and nonlinear reasons.

China launched the Grassland Ecological Subsidy Policy in 2011 for restoring grassland ecology by paying pastoralists to downsize stocking on the degraded grasslands and compensate their income loss from livestock reduction. The policy, the largest payment for ecosystem services program targeting pastoralism in the world, has been so far through two 5-year stages: 2011 to 2015 with a subsidy at 1.5 CNY per standard mu per year and 2016 to 2020 at 2.5 CNY increased to boost the stocking reduction. How was the boost effect? We investigated that stocking responses in 2010, 2015 and 2018 using the panel data of 410 herder households in the subpolicy forage-livestock balance areas in Inner Mongolia, China, tested various attributes on stocking rate and stocking reduction rate at the two stages of the policy using econometric models of random effects and ordinary least squares. This study is the first empirical case containing the two 5-year policy data and with both subsidy and precipitation effects. We confirmed the regulating impact of precipitation on the subsidy policy effect, and more precipitation in the second stage appeared to offset the effect of the increased subsidy. We suggested changing the subsidy targeting mechanism from rewarding stocking reduction to direct grassland restoration.

This study aimed to examine selenite uptake in Medicago sativa L. Potted alfalfa plants were grown in sterilized quartz sand and exposed to 1 and 10 μM selenite for 21 days. Thirty-day-old seedlings and excised roots were used to determine the mechanism of selenite uptake in alfalfa. The following patterns of Selenium (Se) distribution in roots were as follows: lateral roots > taproots and subcellular fraction (I) > fraction (III) > fraction (II). With increasing pH, Se uptake in roots decreased markedly. The dose-dependent Se net uptake at pH 5.5 followed the Michaelis–Menten kinetics. Addition of phosphate decreased Se uptake in the excised roots (P < 0.05), whereas a deficiency in phosphate increased Se uptake (P < 0.05). The results indicate that alfalfa mainly absorbed selenium through lateral roots. Selenite uptake by alfalfa root depended on pH, with the preferential form absorption of as H₂SeO₃ > HSeO₃¹⁻ > SeO₃²⁻. A portion of selenite was absorbed actively and may be mediated by phosphate transporter.