甘肃天然草地毒草危害、防控与综合利用

甘肃拥有天然草地1564.83万hm~2,位列全国第6位。长期以来,由于受干旱、鼠虫害和超载放牧等因素影响,天然草地退化严重,并伴随大量毒草滋生和蔓延,导致大批牲畜中毒,给畜牧业带来严重经济损失。甘肃天然草地常见毒草有78科187属312种,主要毒草有:瑞香狼毒(Stellera chamaejasme)、甘肃棘豆(Oxytropis kansuensis)、黄花棘豆(O.ochrocephala)、小花棘豆(O.glabra)、变异黄芪(Astragalus variabilis)、醉马芨芨草(Achnatherum inebrians)、橐吾(Ligularia sibirica)、苦豆子(Sophora alopecuroides)、马先蒿(Pedicularis resupinata)及栎属(Quercus L.)植物等。本文结合课题组对甘肃天然草地毒草资料整理及实际调查分析,分别就近年来甘肃天然草地毒草对区域草地生态及畜牧业生产造成的毒草灾害、地理分布、毒草种类、防控对策及合理利用进行综述。     

Pastoralists’ perceptions of feed scarcity and livestock poisoning in southern rangelands, Ethiopia

A survey was conducted between April and July 2007 to generate information on dry season feeding management and livestock poisoning in the southern rangelands of Ethiopia. A total of 119 pastoralists were interviewed using a semi-structured questionnaire. Moreover, additional information was obtained through informal discussions. The study revealed that pastoralists have rich knowledge of natural resource management and utilization and employ various strategies such as migration, collection of grasses and pods, and cutting branches to overcome feed scarcity during dry/drought periods. Migration of livestock and people to areas with better grazing is the widely used strategy. However, the implementation of this strategy is diminishing as a result of changes such as bush encroachment, expansion of settlements, and crop cultivation in dry-season grazing lands. The respondents also indicated the presence of poisonous plants in the rangeland, and about 20 such plants were identified by the respondents. Various species and classes of livestock are reported to be affected by toxic plants particularly in the dry and early rainy seasons when feed is in short supply. A more extensive survey is required to document all poisonous plants in the rangelands and to identify the major toxic principles in the different species. Future development interventions should consider the prevailing constraints and potentials of the rangelands with active participation of the pastoralists.     

科尔沁草地有毒植物及保障家畜安全的对策

为了保障家畜采食安全,对科尔沁草地有毒植物进行了大量的调查和资料整理,初步查明了科尔汤草地有毒植物植物共１６４种,隶属于４２科９３属,首次对这些有毒植物进行了生活型和水分生态类型分析,结果表明：有毒植物以多年生中生、中时时生草本植物占多数;在水分条件相对较好的草地类型或局部地段有毒植物分布较多,较常见的有毒植物所含有的主要毒物成分为生物碱、甙类化合物、匝类化合物、酚类及其衍生物、无机物和简单有机舶     

Land Manager Perceptions of Opportunities and Constraints of Using Livestock to Manage Invasive Plants

The ecological impacts of rangeland invasive plants have been widely documented, but the social aspects of how managers perceive their impacts and options for control have been relatively understudied, and successful, long-term invasive plant management programs are limited. In particular, though a growing body of research has identified livestock grazing as the most practical and economical tool for controlling invasive rangeland plants, to date there has not been a systematic assessment of the challenges and opportunities producers and other land managers see as most important when considering using livestock to manage invasive plants. In-depth, semistructured interviews with California annual grass and hardwood rangeland ranchers, public agency personnel, and nongovernmental organization land managers were used to address this need. Although interviewees broadly agreed that grazing could be an effective management tool, differences emerged among the three groups in how they prioritized invasive plant control, the amount of resources devoted to control, and the grazing strategies employed. Interviewees identified key challenges that hinder broad-scale adoption of control efforts, including the potential incompatibility of invasive plant management and livestock production; a lack of secure, long-term access to land for many ranchers; incomplete or insufficient information, such as the location or extent of infestations or the economic impacts to operations of invasive plants; and the temporal and spatial variability of the ecosystem. By identifying key socioecological drivers that influence the degree to which livestock are used to manage invasive plants, this study was able to identify potential pathways to move our growing understanding of the science of targeted grazing into practice. Research, extension, and grazing programs that address these barriers should help increase the extent to which we can effectively use livestock to slow and perhaps reverse the spread of some of our most serious rangeland weeds.     

新疆阿克苏地区天然草地毒草分布及危害状况调查

采用现场调查与资料收集相结合,对新疆阿克苏地区天然草地毒草种类和地理分布及危害等进行了调查。结果表明,阿克苏地区天然草地毒草分布面积62.05万hm2,占可利用草地面积7.12%,年平均牲畜毒草中毒数超过7 000余头(只)。天然草地主要毒草有66种,分属22科,49属,对畜牧业生产造成危害的主要有小花棘豆、苦豆子、苦马豆、骆驼蓬、黄花棘豆、无叶假木贼、盐角草、盐生草、醉马芨芨草、苍耳等。结合调查结果提出了毒草防控建议。     

Toxicoses in livestock from the hemlocks (Conium and Cicuta spp.)

The hemlocks, Conium maculatum (poison-hemlock) and Cicuta spp. (waterhemlock), are poisonous plants that cause sizeable losss to the livestock industry. Clinical signs of poisonhemlock toxicosis are similar in all species of livestock and include muscular weakness, incordination, trembling, initial central nervous system stimulation, depression and death from respiratory paralysis. Poison-hemlock also causes skeletal defects in the offspring of cattle, pigs and sheep and cleft palate in pigs when ingested during specific periods of gestation. The primary toxicants in poison-hemlock are coniine and gamma-coniceine. Coniine predominates in mature plants and seed, whereas gamma-coniceine predominates in early growth of the plant. Waterhemlock is the most violently toxic poisonous plant known. The toxicant is cicutoxin, which acts on the central nervous system, causing violent convulsions and death. Clinical signs of poisoning appear within 15 min after ingestion of a lethal dose and include excessive salivation, nervousness, tremors, muscular weakness and convulsive seizures interspersed by intermittent periods of relaxation and a final paralytic seizure resulting in anoxia and death. Elevated activities of lactic dehydrogenase, aspartate aminotransferase and creatine kinase in blood are observed, indicative of muscular damage. Toxicoses from poisonhemlock and waterhemlock generally occur in early spring when both plants emerge before other, more palatable plants begin to grow. All parts of the poison-hemlock plant are toxic. The root or tubers of waterhemlock are toxic; however, experimental evidence concerning the toxicity of other plant parts is inconclusive.     

家畜毛瓣棘豆中毒研究

毛瓣棘豆Oxytropis serioopetala是“疯草”中棘豆属重要的有毒植物之一,主要分布于西藏南部的河滩沙砾地。当地家畜采食后大量中毒,严重的发生死亡,给西藏畜牧业带来很大损失。从毛瓣棘豆的生态分布、危害、毒性成分、中毒诊断和治疗、防除利用、研究展望等方面进行了综述。     

Mycotoxic tremorgens of Claviceps paspali and Penicillium cyclopium: a comparative study of effects on sheep and cattle in relation to natural staggers syndromes

Claviceps paspali sclerotia were dosed orally at various levels to sheep and cattle and the neurotoxic effects are described. Evidence is presented which indicates that the tremors are produced by a neutral tremorgen fraction. The ergot alkaloids, principally D-lysergic acid alpha-hydroxyethylamide and its isolysergic acid isomer, are not involved. The mixture of C paspali tremorgens has not been separated and characterised but its components are chemically related to other known tremorgens, such as penitrem A, produced by saprophytic moulds, notably Penicillium cyclopium. P cyclopium mycelium and C paspali sclerotia were dosed to produce comparable effects in sheep and in cattle. Similarly, effects of penitrem A and tremorgen concentrate of C paspali were compared after intravenous dosage to sheep. Observed enurotoxic effects of both moulds were identical in most respects. A low level of tremorgenic activity was detected at the honeydew stage of C paspali. These findings are discussed in relation to staggers syndromes occurring in grazing livestock.     

Tightly Bunched Herding Improves Cattle Performance in African Savanna Rangeland

Rotational grazing management approaches are regarded as strategies for sustaining rangeland productivity and continue to be applied across many parts of the world. In Africa, livestock farmers implementing rotational grazing often switch from traditional loosely bunched herding (LBH), in which animals within a herd are allowed to spread out naturally when foraging, to tightly bunched herding (TBH) with limited herd spread to increase animal impact on the range. However, there is little scientific information on the actual direct (short-term) effects of this altered herding strategy on livestock productivity. We investigated the direct effects of TBH versus LBH on foraging behavior, nutrition, and performance (weight gain) of cattle in a semiarid savanna rangeland in central Kenya. We conducted the study across two habitat types: a heterogeneous red soil habitat and a relatively homogeneous black cotton soil habitat. Across both habitats, cattle traveled 9–15% less, foraged 10–29% more efficiently, and put on 14–39% more weight when managed with TBH as compared with LBH. These changes occurred despite the fact that stock densities were double to several times higher under TBH, and cattle under this herding regime foraged less selectively, consuming preferred plants less (especially in the black cotton soil habitat) and consuming diets with lower crude protein content (in the red soil habitat). Financial projection showed that the benefit of increased cattle performance under TBH could sufficiently outweigh increased cost of additional labor required to implement this herding strategy. These findings suggest that TBH, as practiced here, can be implemented without livestock production or financial losses. Further, the research demonstrated reduced grazing selectivity under TBH indicates that this herding strategy could potentially be used to reduce grazing pressure on preferred forage plants and maintain herbaceous species diversity without sacrificing cattle performance.     

张掖肉牛环境适应性研究

张掖肉牛分布在河西荒漠区,主产于河西走廊一带,是当地重要的经济畜种,也是典型的高原模式畜种,具有很强的环境适应性。本文对高海拔高寒地区放牧的张掖肉牛与平原区放牧的张掖肉牛进行了繁殖性能和生长性能的研究,并观测其环境适应性及抗病力。     

Rotational Grazing Systems and Livestock Grazing Behavior in Shrub-Dominated Semi-Arid and Arid Rangelands

Rotational grazing systems (RGS) are often implemented to alleviate undesirable selective grazing by livestock. At both fine and coarse scales, livestock selectively graze individual plants, patches, communities, and landscapes. Smaller pastures, increased stocking density, and rotation allow managers to constrain livestock movement and determine season and frequency of grazing, potentially limiting selectivity and preventing repeated grazing of preferred plants. However, in arid and semi-arid rangelands, forage growth is limited primarily by precipitation rather than defoliation frequency. When soil moisture is adequate, forage is abundant and defoliation levels are typically low, and repeated, intensive defoliation of preferred plants is less likely than in more mesic areas where more consistent precipitation and soil moisture storage allows animals to establish and maintain spatial hierarchies of grazing patterns. Many southwestern rangelands contain diverse vegetation, which provides quality forage during different times of the year. These spatial and temporal patterns of forage distribution may not be amenable to manipulation with RGS. Tracking data show that livestock often alternate among locations within pasture boundaries and can opportunistically exploit areas with higher quality forage when they are available. Higher stock densities combined with higher stocking rates can increase livestock use of less preferred areas, but overall distribution patterns of intensive-rotational and extensive grazing systems are often comparable at similar stocking rates and distances from water. Management that ensures that grazing of riparian areas does not occur during the critical late summer period may be more beneficial than RGS that periodically defers livestock use throughout the grazing season. In arid and semi-arid shrublands, timely adjustments to animal numbers and practices that improve grazing distribution at regional and landscape scales are more likely to be effective in maintaining or improving rangeland health than fencing and RGS.     

不同放牧强度对当年混播草地的影响

研究了云南高降雨地区混播草地播种60 d后,不同放牧强度(0.5,1和1.5黄牛单位/公顷)对草地密度、盖度、高度、频度和生物量的影响。结果表明,放牧能明显抑制一年生禾本科杂草及播种多年生禾本科牧草的生长,但对白三叶和草地有害植物的生长都有促进作用。     

中国天然草地有毒植物及其放牧家畜中毒病研究进展

中国是世界草地资源大国,天然草地作为我国面积最大的陆地生态系统和重要的绿色生态屏障,具有多种生态功能,同时也是发展草地畜牧业的重要基地和牧民最基本的生产生活资料。但长期以来,人们只重视天然草地的生产功能,而忽视了对天然草地生态系统的保护,使得我国天然草地长期处于过度利用状态,造成草地退化,进一步引发有毒植物等生物灾害多发、频发,可食牧草种类和产量锐减,生物多样性失调及生态环境恶化。本文简要概述了我国天然草地有毒植物的种类与分布,介绍了有毒植物给目前我国天然草地以及畜牧业带来的经济损失以及危害,针对疯草类有毒植物、乌头属有毒植物、橐吾属有毒植物、瑞香狼毒、醉马芨芨草、紫茎泽兰6种危害较为严重的有毒植物的毒理学与中毒病及其防治技术方面的研究进展作了概述,对未来在有毒植物中毒的防控方面提出几点建议,旨在为我国草原牧区放牧家畜有毒植物中毒病综合防控和健康养殖提供理论指导。     

我国天然草地毒害草化学防控研究进展

我国拥有天然草地面积3.93亿hm2,位居世界第二。天然草地是我国重要的绿色生态屏障,具有调节气候、防风固沙、保持水土、涵养水源、固氮储碳、净化空气、维护生物多样性等重要功能,也是发展草地畜牧业的重要物质基础。长期以来,由于天然草地干旱、鼠虫害、超载过牧等因素的影响,导致草地严重退化、沙化、生态持续恶化,可食牧草急剧减少,而毒害草却大量滋生和蔓延。毒害草导致牲畜中毒呈现多发、频发,甚至暴发态势,经济损失严重,被称为天然草地的"绿色杀手"。对我国西部地区牧民的生产、生活、社会稳定和国家生态安全造成威胁。论文围绕毒害草对草地畜牧业的危害、除草剂发展历程、除草剂种类、除草剂在防控主要毒害草方面的应用等方面进行综述,并提出今后毒害草防控中应注意的问题,对科学认识毒害草在天然草地中的生态作用和综合利用有指导意义。     

Consumption of Low Larkspur (Delphinium nuttallianum) by Grazing Sheep

Low larkspur (Delphinium nuttallianum Pritz.) poisoning causes serious economic loss to livestock producers that graze cattle on foothill and mountain ranges in western North America. In general, all Delphinium spp. are five times less toxic to sheep than to cattle. Because low larkspurs are less toxic to sheep than cattle, grazing sheep before cattle on rangelands with dense populations of low larkspur can reduce larkspur density and risk of poisoning to grazing cattle. All previous published work on sheep and larkspur interactions has involved tall larkspurs. This series of studies was conducted to determine if sheep would consume sufficient low larkspur to reduce subsequent risk to cattle. Four summer trials were conducted in Collbran, Colorado, and Soda Springs, Idaho on pastures with dense (> 9 plants · m^?2) low larkspur populations. In all trials, sheep ate very little low larkspur (< 0.5% of bites). During one final trial using high sheep density (two sheep · 0.015 ha^?1 for 9 d), sheep consumed little low larkspur, but animals appeared to trample much of the low larkspur. Toxic alkaloid concentrations in low larkspur ranged from 1.1 mg · g^?1 to 1.6 mg · g^?1 in all trials. The use of sheep to graze low larkspurs to reduce subsequent consumption by grazing cattle does not appear to be a viable option.     

Production and Environmental Implications of Equine Grazing

Horses' physical and digestive well-being is often enhanced when allowed to graze on pastures. Furthermore, a well-managed pasture can contribute to economic viability. Grazing can however have deleterious effects on the environment if not properly managed. Although equine grazing, defecating, and ground trampling behavior is unique from that of other livestock species, pasture management practices are often based on those derived from cattle grazing. This review summarizes the current knowledge of impacts of equine grazing on pasture quality and environment and identifies gaps where further information is needed to formulate and recommend sustainable grazing methods specific to equine.     

Effect of Aboveground Mass Removal on Toxicity of Geyer’s Larkspur,with Important Implications for Grazing Management

The many species of larkspur (Delphinium spp. L.) are among the most dangerous poisonous plants on rangelands in the western United States, causing death losses estimated at 2 − 5% (up to 15%) per year for cattle grazing in larkspur habitat. Other effects, such as altered grazing management practices and consequent lost forage quantity and quality, are significant but poorly understood. Current best management practice recommendations are based on seasonal avoidance, with little evidence that this is practical or effective. Our ongoing research has presented evidence that instead it may be possible to manage grazing such that all cattle eat some larkspur, but none eat a fatal dose. This raises the question of the potential response of larkspur to being grazed. In this study we examine the response of Geyer’s larkspur (D. geyeri Greene) to two seasons of 25% or 75% aboveground plant mass removal. The 75% treatment led to significantly lower alkaloid concentrations (mg • g^− 1) and pools (mg per plant), while the 25% treatment had a lesser effect. Combined with lessons from previous studies, this indicates that Geyer’s larkspur plants subject to aboveground mass removal such as may occur via grazing can be expected to become significantly less dangerous to cattle. We suggest that the mechanisms for this reduction are both alkaloid removal and reduced belowground root mass, as significant evidence indicates that alkaloids are synthesized and stored in the roots. These results continue to build support for our theory that the solution to the seemingly intractable challenge of larkspur poisoning lies not in avoidance but in the skill of managers and the wisdom of herds.     

甘肃天然草原主要毒草分布、危害及其防治对策

甘肃天然草原有毒植物有18科39属178种。对家畜危害性大、分布较广的毒草主要有:豆科棘豆属的甘肃棘豆Oxytropis ransuensis、黄花棘豆O．ochrocephala、小花棘豆O.glabra、糠形棘豆O.falcate、蓝花棘豆O．coerulea,豆科黄芪属的变异黄芪Astragalus variabilis,瑞香科狼毒属的狼毒Sellera chmaejas- me,禾本科芨芨草属的醉马草Achnatherum inebrians、由于自然和人为因素的影响,甘肃省天然草原退化严重,生态环境逐渐变劣,有毒植物大量繁衍增生,家畜采食后,中毒的现象时有发生,造成较大的损失。为此,对毒草的地理分布、生境条件、家畜中毒症状做了简要阐述,提出了防治对策,以减少家畜中毒死亡。     

Polioencephalomalacia in range cattle.

Polioencephalomalacia developed in 27 of 225 cattle grazing on 486 hectares of dry, short, grama grass pasture. Chemicals in drinking water, toxin from nitrate-utilizing ruminal bacteria, and documented poisonous plants were considered as etiologic agents. Attempts to reproduce the disease by injecting mice and dosing sheep with broth filtrate from nitrate-utilizing ruminal bacteria were not successful. Mushrooms collected from the pasture and fed to a cow did not reproduce the disease.