植物补偿性生长与草地可持续利用研究

1998～1999年,对不同放牧强度下内蒙古大针茅草原植物的利用率和净初级生长量的研究结果表明绵羊对草群和大针茅的采食率与牧草的叶龄结构和生长速率密切相关;在降雨量充沛的情况下,随着牧草采食率的提高,草群和大针茅净初级生长量呈现单峰型增长动态,草群和大针茅的高峰值分别出现在45%～55%和55%～60%的采食率范围,并且分别在30%～55%和35%～65%的采食率范围内表现出超补偿生长,超出此范围则表现欠补偿生长;依据草群和大针茅补偿生长规律,大针茅草原适宜采食率在45%～55%之间,相应载畜率为3.5只羊/夏、秋季/hm2.在此采食率范围内,草地可以获得长久的超补偿或等补偿生长,草地的生产能力增加,草地植物组成维持相对稳定,可保证草地的持续利用.     

植物补偿性生长与草地可持续利用研究

1998－1999年，对不同放牧强度下内蒙古大针茅草原植物的利用率和净初级生长量的研究结果表明：绵羊对草群和大针茅的采食率与牧草的叶龄结构和生长速率密切相关；在降雨量充沛的情况下，随着牧草采食率的提高，草群和大针茅净初级生长量呈现单峰型增长动态，草群和大针茅的高峰值分别出现在45％－55％和55％－60％的采食率范围，并且分别在30％－55％和35％－65％的采食率范围内表现出超补偿生长，超出此范围则表现欠补偿生长；依据草群和大针茅补偿生长规律，大针茅草原适宜采食率在45％－55％之间，相应载畜率为3.5只羊／夏、秋季／hm^2。在此采食率范围内，草地可以获得长久的超补偿或等补偿生长，草地的生产能力增加，草地植物组成维持相对稳定，可保证草地的持续利用。     

贝加尔针茅草原围栏封育和自由放牧条件下植物结实数量的研究

在两个不同的降水年份,于内蒙古锡林郭勒草原东部的贝加尔针茅草原上,采用收获单位面积草原群落植物全部种子的办法,对比观察了连续自由放牧或阶段性放牧与围栏封育条件下植物结实量及结实植物种类和出现率的差异,同时观察了围栏内、外贝加尔针茅种子生产数和狼毒单花序成花数的差异.结果表明,植物结实受放牧采食和降水条件的共同影响.同围栏封育相比,连续自由放牧不利于植物结实.而春季放牧夏秋休闲的阶段性放牧可以使植物结实性迅速恢复,这种影响对部分植物来说,甚至超越于降水的影响.说明了放牧管理方式对维持植物良好结实性的重要性.     

山地牧道与植被空间异质性研究评述

山地牧道和沿牧道放牧改变植被空间异质性。综合国内外研究进展,将山地牧道的涵义扩展为家畜在山地垂直空间移动的固定路线、放牧往返小道、相对固定的采食路径以及践踏小径等,并总结了山地牧道的形成与分布规律,重点评述了山地牧道与植被空间异质性相互作用机制。山地牧道作为一种线状廊道,为物种扩散提供通道、生境,分割斑块景观,影响植被边界动态,在不同尺度上影响植被空间异质性;家畜沿牧道的选择采食与植被空间异质性相互影响,家畜还通过践踏和排泄改变植被空间异质性;家畜采食、践踏和排泄综合作用于土壤,通过影响土壤异质性间接影响植被的空间分布。山地牧道在动物行为学、放牧生态学研究中具有理论和实践价值,可以为监测植被退化、控制载畜量提供依据。     

贝加尔针茅草原围栏封育和自由放牧条件下植物结实数量的研究

在两个不同的降水年份，于内蒙古锡林郭勒草原东部的贝加尔针茅草原上，采用收获单位面积草原群落植物全部种子的办法，对比观察了连续自由放牧或阶段性放牧与围栏封育条件下植物结实量及结实植物种类和出现率的差异，同时观察了围栏内、外贝加尔针茅种子生产数和狼毒单花序成花数的差异。结果表明，植物结实受放牧采食和降水条件的共同影响。同围栏封育相比，连续自由放牧不利于植物结实。而春季放牧夏秋休闲的阶段性放牧可以使植物结实性迅速恢复，这种影响对部分植物来说，甚至超越于降水的影响，说明了放牧管理方式对维持植物良好结实性的重要性。     

施肥和刈割处理模拟放牧对西北针茅生长的影响

放牧是天然草地最主要的利用方式,其对于草地的影响主要是采食、践踏和排泄作用。不同畜种具有不同的牧食行为,对于草地的影响也不同。为了研究牛羊混合放牧对于西北针茅（Stipa sareptana var. krylovii）草原建群种的影响,本研究设置了对照、添加牛粪+刈割（模拟牛单牧）、添加羊粪+不刈割（模拟羊单牧）、添加牛粪+羊粪+刈割（模拟牛羊混牧）4种处理,在6-12月季测定了西北针茅的生长参数。结果发现在模拟牛羊混牧处理下,西北针茅的植株高度较高,分蘖数适中,而根系生产量相对较小。综上所述,牛羊混合放牧有利于提高西北针茅草原草地生产力的可能性较大;动态观测发现不同处理下西北针茅的根系生产主要发生在生长季,根系的死亡主要发生在非生长季。     

放牧强度对高寒草甸植物叶片生态化学计量特征的影响

在青藏高原高寒草甸封育、适度放牧、重度放牧3种放牧强度中,选取并测定了异针茅、麻花艽、蒲公英3种植物叶片中C、N、P的含量,探讨了植物叶片的化学计量特征对不同放牧强度的响应机制。结果表明:3种植物叶片在不同放牧强度样地中C含量无差异;3种植物叶片N、P含量在重度放牧草地中高于其他两种放牧强度,且重度放牧草地整体受N限制,其他两种草地植物受P限制;重度放牧草地的C/P、N/P比值显著低于其他两种草地放牧强度中的比值,说明重度放牧草地3种植物采取了快速生长策略,而且不同物种在不同生境中受养分限制的程度不同。以上结果说明草地的放牧强度不同,在很大程度上间接改变植物对养分的利用状况,不同植物对相同生境有不同的适应策略。     

放牧对藏北高寒草地优势种和伴生种生物量分配的影响

以藏北高寒草地优势种紫花针茅（Stipa purpurea）和伴生种小叶棘豆（Oxytropis microphylla）为研究对象,探讨围封和放牧草地中两种植物在叶、茎、根间生物量分配的差异性。结果表明：放牧对紫花针茅和小叶棘豆的叶、茎的质量比影响显著,两者叶-茎和叶-根的异速生长指数均升高,根-冠的异速生长指数均降低,植株叶-茎和叶-根的异速生长关系出现趋同化。种间根、茎和叶生物量分配存在显著差异性,小叶棘豆叶-茎、叶-根和茎-根的异速生长指数均大于紫花针茅。放牧改变了植物各器官间的权衡策略,紫花针茅在叶-茎权衡关系中更益于茎的生长,小叶棘豆更益于叶的生长;在叶-根和茎-根权衡关系中,小叶棘豆更倾向于叶,紫花针茅则更倾向于茎;相对于根系,两者均在放牧后分配更多资源到地上部分。放牧环境和种间差异导致的植物各器官间生物量分配的变化对群落组成演替有着重要意义。     

大针茅对放牧生态系统植物群落地上生物量的调控作用

通过放牧梯度试验,研究放牧对内蒙古典型草原5种优势植物在个体、种群和群落水平上的影响,探讨大针茅(Stip grandis)对放牧生态系统植物群落地上生物量的调控作用。结果表明:个体水平,中轻度放牧对以大针茅和糙隐子草(Cleistogenes squarrosa)为代表的丛生禾草株高影响较小,对以羊草(Leymus chinensis)、黄囊苔草(Carex korshinskyi)和米氏冰草(Agropyron michnoi)为代表的根茎型禾草株高影响较大,植物株高的降低与个体地上生物量减少呈显著正相关。种群水平,大针茅种群生物量对放牧的响应迟缓,羊草、米氏冰草、糙隐子草和黄囊苔草种群生物量的减少与多度减少呈显著正相关。群落水平,大针茅的耐牧性使其成为资源重配的获益者,轻中度放牧干扰下,其地上生物量的补偿生长缓冲了放牧对群落的影响,对维持群落生产力与功能稳定性起重要的调控作用。     

短期内混合放牧对荒漠草原植物群落特征的影响

本文通过设置不同放牧方式(单一放牧、混合放牧和不放牧),以希拉穆仁荒漠草原植物群落为研究对象,研究混合放牧对荒漠草原植物群落特征的影响。得出以下结果:(1)在混合放牧处理中,放牧牛对短花针茅的采食导致短花针茅高度降低,可减弱针茅果实对羊皮的伤害。(2)混合放牧下由于不同牲畜食性选择不同,可以很好的利用草地资源。牛羊的采食习惯不同,羊喜爱采食植株较低,鲜嫩多汁的牧草,而牛会采食植株较高的植物。(3)在较短的放牧时间里,由于不同牲畜对植物资源的利用不同,植物的多样性有所提高。     

饲养模式对绵羊冷季生产效益的影响

在肃南裕固族自治县选择草场类型一致,绵羊(Ovisaries sp.)体况相近的3个牧户分别采取暖棚全舍饲(试验组Ⅰ),放牧+补饲(试验组Ⅱ)以及全放牧(对照组)3种饲养方式,通过测定整个繁殖周期绵羊体质量变化、母羊繁殖率和羔羊成活率指标,比较不同饲养模式对绵羊生产效益的影响.结果表明,3种饲养模式下越冬母羊体质量损失...     

Is the grazing tolerance of mesic decreaser and increaser grasses altered by soil nutrients and competition?

An ability to tolerate recurrent defoliation likely plays a role in the compositional shift from decreaser to increaser species with overgrazing of mesic grassland, but the grazing tolerance of local species has not been extensively studied. The growth response of two decreasers, three Increaser II grasses, and an Increaser III species to frequent, severe defoliation under three levels of competition from neighbours and two levels of soil nutrients was examined in a pot trial. The effects of competition and especially nutrients markedly modified the defoliation tolerance of different species, and grazing response groups varied in the manner in which their defoliation responses were mediated by these interactions. Contrary to expectation, defoliation constrained potential productivity most in nutrient-rich, competition-free environments, probably because it exacerbates a carbon limitation on growth. However, nutrient enrichment did enable Increaser II grasses, but not other species, to better tolerate intense defoliation, explaining why they can persist on intensively grazed fertile patches and in heavily stocked grassland, such as in communal areas, where nutrients are more available. It is concluded that grazing tolerance is not a fixed property of species or grazing response groups but depends on biotic and abiotic environmental factors.     

Feeding value of pastures for horses

The feeding value of fresh pasture grazed in situ is determined by animal performance or productivity and could be relatively easily established for growing and lactating horses. Despite this, there is a lack of published information on the relative feeding value of different pastures and forages grazed by horses in New Zealand and the world. In addition, for adult breeding or non-breeding and young or adult sport or performance horses, the definition of feeding value and its determination remain problematic.

Limited information suggests that the feeding value of perennial ryegrass-based pasture in New Zealand for young growing horses is high, and growth rates for Thoroughbred horses fed solely on pasture in New Zealand are similar to those reported from the Northern Hemisphere where grain-based supplements are fed in addition to pasture or other forages. Attempts to assess the ability of fresh pastures to meet the nutrient requirements of horses are hampered by problems associated with determination of feed intake by grazing horses and lack of knowledge of the digestibility and utilisation of digested nutrients, including the relative bio availability of macro- and micro-minerals in pasture. A further challenge for future research is to determine the effect of herbage allowance and grazing behaviour, including pasture species preferences, on voluntary feed intake by grazing horses.

Grazing pasture has benefits for equine health and well-being including reduced risk of some nutrition-related disorders and reduced prevalence of stereotypic behaviour. Pastured horses have greater freedom for expression of natural behaviours including social interaction and exercise. However, grazing pasture is also associated with animal health problems, particularly parasitism and diseases related to pasture-associated toxins.     

华北农牧交错带地区放牧强度对草地土壤氮营养的影响

以放牧2年的改良新麦草草地为对象,对放牧期间及停牧后不同放牧强度区土壤全氮、铵态氮、硝态氮、微 生物量氮含量变化进行研究。结果表明,在华北农牧交错带地区,放牧草地土壤氮水平与放牧强度紧密相关。在放牧期 间,0~10 cm和10-20 cm土层,各项指标均随放牧强度增加而增加,停牧后,各处理间差异缩小,表明放牧强度对土壤 氮水平的影响有较强的现时性,而且重牧区土壤氮营养水平呈现下降趋势。     

Effects of farm management practices on cattle grazing behaviour and the potential for transmission of bovine tuberculosis from badgers to cattle

Despite the large body of circumstantial evidence to suggest a link, the means by which bovine tuberculosis is passed from badgers to cattle remains unclear; pasture contamination with the urine, faeces and/or sputum of infectious badgers is believed to be the main route of transmission. Therefore the behaviour of grazing cattle was studied to determine whether they avoided investigating and/or grazing pasture contaminated with badger excreta, and whether different farm management practices enhanced the potential for disease transmission. Active latrines were avoided by most cattle until the sward length in the rest of the field was reduced, after which there was an increasing likelihood that active badger latrines would be grazed. Most of the cattle grazed active badger latrines, but cattle of low rank within the herd grazed latrines more heavily. Farm management practices that reduced the availability of long swards shortened the period of investigative behaviour and greatly enhanced the risk that cattle would graze active badger latrines. Cattle were more likely to graze pasture away from latrines that was contaminated either with badger urine or single faeces. Because bacilli remain viable in the soil for up to 2 years, there is the potential for bacilli to accumulate at active badger latrines, and these could pose a significant risk to cattle, even when the latrine is no longer being used by badgers. Cattle readily grazed the lush sward at disused latrines, during which they could ingest contaminated soil; the amount of soil ingested increases as sward length decreases.     

不同植酸酶对饲喂低磷日粮肉鸡生长性能及粪N、P排泄的影响

采用306只艾维茵肉鸡研究低磷日粮中添加两种不同植酸酶对肉鸡生产性能、养分利用率及氮、磷排泄的影响。试验共分3个处理组,即对照组、试验Ⅰ组和试验Ⅱ组,每个处理组3个重复,每个重复34只鸡。对照组饲喂正常磷水平的日粮;试验Ⅰ组饲喂低磷＋植酸酶Ⅰ的日粮;试验Ⅱ组饲喂低磷＋植酸酶Ⅱ的日粮。试验结果表明,添加植酸酶替代日粮中部分无机磷,肉鸡的日增重和日采食量与对照组相比降低,但差异不显著（P＞0.05）;提高了肉鸡的存活率（P＜0.05）和钙、磷利用率（P＜0.05）;同时氮利用率有一定程度改善（P＞0.05）,显著减少了氮、磷的排泄量（P＜0.05）。添加植酸酶Ⅰ与添加植酸酶Ⅱ相比,肉鸡的日增重与日采食量提高（P＜0.05）,氮的排泄量显著降低（P＜0.05）,磷的排泄量没有差异。     

Factors regulating tapeworm populations: dispersion patterns of Taenia hydatigena eggs on pasture

Two grazing trials using 'sentinel' lambs were undertaken to measure changes in the availability of eggs within 30 metres of deposition by dogs infected with Taenia hydatigena. In the first trial the experimental pasture was divided into nine equal plots; in the second trial, each of the nine plots was divided into sub-plots. In each trial, infected dogs were placed on the pasture for 10 days. Lambs were then grazed for 10 days immediately, 36 days and 56 days after the dogs had been removed. Changes in the dispersion pattern of the eggs over time and space were assessed by examination of the lambs for cysts at autopsy. In both trials, eggs spread radially within the grazing zone within 10 days, but 36 days after the removal of the dogs, their availability to the lambs was markedly reduced. In the first trial at five weeks, the height of grass (between 3 cm and 15 cm) did not modify egg availability. In both trials, despite differences in rainfall affecting the growth of grass and associated factors similar egg losses occurred.     

Response of young cattle to anthelmintic treatment during autumn in a Mediterranean-type climatic environment

A worm control programme in which heifers were treated with anthelmintic on three occasions during autumn, was tested in the Mediterranean-type climatic environment of south-west Western Australia. The experiment aimed to determine if the treatments would prevent the heifers contaminating their pastures with worm eggs during autumn, thereby improving their growth performances the following winter. An attempt was made to measure the availability of infective larvae of abomasal worms on the heifers' pastures during early winter by counting the worms in steers, previously of low worm status, that grazed with the heifers from late autumn until the start of mating in mid-winter.

The anthelmintic treatments reduced the contamination of pasture for most of autumn. The treated heifers that grazed these pastures grew faster, and by the start of mating two months after the last treatment were about 22 kg heavier, than untreated heifers grazing contaminated pasture. At the end of mating six weeks later the difference was 45 kg in favour of the treated heifers. At this time half the heifers grazing contaminated pasture were treated with anthelmintic. The following month these heifers grew faster than those left untreated, but by late November they had not attained the wieght of the heifers grazing uncontaminated pasture.

The heifers that grazed uncontaminated pasture produced more calves the following autumn than did those grazing contaminated pasture. The abomasal worm counts of the steers, with a mean of about 46 000 worms, failed to reveal any difference between treatments in the availability of larvae of abomasal worms on pasture. However, it was concluded that the treatments probably exerted their effect on growth rates by reducing the number of infective larvae ingested by heifers grazing the uncontaminated pasture during winter.     

小五台亚高山草甸植物种分布的生境条件解释

通过野外植被调查获取小五台亚高山草甸的第一手植被数据,结合室内外测定和模拟的研究区景观尺度的生境特征指标,分析了研究区亚高山草甸地段植物物种与环境因子之间的定量关系。典范对应分析(canonical correspondence analysis,CCA)排序的结果表明,1)在小五台的亚高山草甸分布地段,热量、养分和水分条件构成了其生境特征差异的基本格局;2)依据研究区的物种在热量、养分和水分梯度上的分布位置,可以划分为暖干、冷干、暖湿、冷湿、凉干、普适和耐干扰型几类物种;3)对于生境温度、养分及水分有特殊偏好的物种可以较好地指示研究区的生境特征。     

Advances in pasture management for animal productivity and health

A wide range of management techniques is available to enhance quantity and quality of forage supply to grazing animals throughout the annual production cycle. Within broad limits, dry matter (DM) production is relatively insensitive to management of defoliation frequency, severity and duration. However defoliation management has effects on feed quality which can be enhanced, in particular, by control of pasture growth in the spring through maintenance of relatively low average pasture masses. Treading damage can have significant immediate and ongoing effects on pasture production and farmers can use a range of management techniques to minimise these.

Fertiliser application practices have a potent influence on pasture production and seasonality of that production. Available soil nitrogen is the primary nutrient deficiency limiting production in New Zealand's characteristically grass-dominant pastures. Nitrogen fertiliser usage has increased markedly in recent years, particularly to grow substantially greater amounts of forage during the cool season, and this trend looks set to continue. However, the use of nitrogen fertiliser has important environmental implications.

Pasture renewal and forage crop use has also increased in recent years. Care needs to be taken in conducting cost-benefit analyses, selecting the options that best meet the needs, and in establishment and subsequent management practices. Ryegrass (perennial and hybrids) and white clover remain the primary choice for permanent pasture renewal, the availability of safe endophytes having largely alleviated effects of endophyte toxicosis. Special-purpose mixtures are used, especially in dry environments. Italian ryegrasses, brassicas and chicory are common choices for forage crops. A range of management techniques can be used to alleviate deleterious effects of some forages, including ryegrass endophyte toxicosis, facial eczema, and toxins associated with Fusarium fungi. Generally these techniques are not totally effective. More research is required to increase our understanding of these disorders, and in order to develop more effective and reliable management practices.