放牧绵羊选食次序和季节性食谱重叠

通过对牧草适口性指数的建立和绵羊选食牧草次序的划分，研究了大针茅草原放牧绵羊季节性食性特点和食谱结构重叠。结果表明，牧草的适口性随着季节的变化而不同，导致绵羊的日粮组成各季间产生一定的渐变性。从采食量的大小来看，糙隐子草、知母、冷蒿和羊草为该草场放牧绵羊的四季平衡牧草。     

放牧绵羊选食次序和季节性食谱重叠

通过对牧草适口性指数的建立和绵羊选食牧草次序的划分，研究了大针茅草原放牧棉羊季节性食性特点和食谱结构重叠。结果表明，牧草的适口性随着季节的变化而不同，导致绵羊的日粮组成各季间产生一定的渐变性。从采食量的大小来看，糙隐子草，知母，冷蒿和羊草为该草场放牧绵羊的四季平衡牧草。     

灌丛草地放牧山羊的牧草适口性与嗜食性及山羊采食率研究

通过对放牧山羊的牧草适口性，嗜食性和采食率及其相互关系的分析，表明山羊放牧对灌丛草地的植物适口性、嗜食性比率和采食率均以灌木嫩枝叶，中禾草和苔草属植物较优。季节性规律为：春季山羊喜哺食灌木嫩枝叶，灌木嗜食性比率较高，采食率也较高，夏季山羊喜草本植物，草本植物的嗜食性比率高于灌木，秋季山羊较喜啃食灌木枝叶，嗜食性比率灌木高于草本植物，采食率低于春季，灌木采食率高于草本植物。     

绵羊牧食行为及其与植物群落斑块关系的研究

本试验对群落结构、绵羊的牧食行为及其与植物群落斑块的关系进行了观测和研究。结果表明:轮牧处理群落斑块结构优于自由放牧处理;从绵羊食谱构成来看,轮牧处理牧草品质明显优于自由放牧处理;家畜采食路线轮牧处理较自由处理短;影响绵羊采食行为的因素主要是草地空间异质性,采食频率这个指标对草场的植物种类组成较为敏感,可以用来较好地反映绵羊采食行为特征与草场空间异质性间的关系。     

高山草原绵羊放牧生态及消化代谢的研究：Ⅰ放牧绵羊嗜食性研究

利用植物显微技术镜检法和食道瘘管法对放牧绵羊采食的高山草原植物成分与嗜食性指数进行分析。结果表明，绵羊在黄草期采食植物成分比青草期多，其嗜食性指数在不同时期变幅较大，随着冬季来临，绵羊对草地植物的嗜食性不如青草期强烈，至某些植物嗜食性是相对稳定的。     

利用饱和烷烃技术对短花针茅荒漠草原放牧绵羊食性的测定

为进一步研究饱和烷烃技术在放牧绵羊食性测定中的应用,本研究在4.4 hm2放牧试验区内,放牧8只蒙古羊,分别于6、9和11月利用饱和烷烃技术对放牧绵羊的食性进行测定.结果表明,同一季节,不同牧草的烷烃模式存在差异,其中以C27和C31差异最为显著,C33次之,C29最差.绵羊的食性表现出明显的季节性变化,夏季羊只所食的牧草主要以冷蒿、无芒隐子草和银灰旋花为主,分别占79.68%、12.12%和7.30%,而短花针茅只占0.90%;而进入秋季后,随着适口性好植物密度的降低,羊只开始对短花针茅进行采食,由原来占食入牧草总量的0.90%升高到3.81%,同时无芒隐子草的采食量也开始增加,由原来占食人牧草总量的12.12%提高到23.57%;冬季家畜采食牧草的种类开始减少,冷蒿占羊只采食量的86.26%,无芒隐子草和银灰旋花分别减少到8.33%和5.41%,而对短花针茅不采食.综上,饱和烷烃技术可以准确测定短花针茅荒漠草原放牧绵羊的食物组成.     

牧草嗜食性指数的分析

<正> 家畜对各种植物的嗜食性,一般用来描述放牧家畜的牧食习性,或者用来估测放牧家畜采食牧草的食入量。许多草原科学工作者根据生物种群中捕食者和被捕食者的关系,建立了许多表示嗜食性指数的数学模型。下面是表示放牧家畜对不同植物种的嗜食性指数的几个数学模型及实验结果。     

放牧家畜采食的调控

放牧家畜的采食行为受不同调控途径调控。视觉、嗅觉、味觉、触觉、学习途径促使家畜产生正向或负向的采食经验,家畜通过采食经验自发地对草地进行可持续利用与管理。采食经验的主要内容是家畜通过各个调控途径将草地牧草的物理指标与牧草的适口性建立联系。家畜可通过视觉将牧草的高度、密度、颜色等与牧草适口性建立联系;通过嗅觉、味觉将牧草的气味、味道与牧草适口性建立联系;通过触觉将牧草的物理性质与牧草适口性建立联系。合理的放牧管理制度和生境条件也可调控家畜的采食行为。     

南非干燥台地灌木放牧研究

对实际放牧率与绵羊采食各种干燥台地灌木茎的程度之间的关系进行了研究。南非干燥台地的农户与研究人员中有一个经验原则,即绵羊采食灌木的直径接近或小于2mm。这项假设已经历了3年的检验。对Pentzia spinescens和Rosenia humillis这两种最常见牧草品种,用游标卡尺测量了它们的新近被采食的茎直径。在估计现有载畜量时所使用的可食干物质的估计值是将刈割后的干物质分成可食与不可食物质两类为基础的。此分类标准为2mm。关于绵羊自由采食直径高达2mm的茎干的假设是不成立的。适口性差的品种其采食茎直径很少达到2mm,而适口性好的品种其采食茎直径通常高于5mm。已证明适口性差的品种被绵羊采食的茎直径平均为1.4～1.6mm。这个结果直接影响了估计干物质量来估算载畜量的方法。这个地区长期载畜量额定值为30hm~2/大家畜单位;基于放牧率试验所得的每公顷净收益资料,求得载畜量为33.4hm~2/大家畜单位。放牧率与被采食茎直径的关系求得的最佳载畜量为32.5hm~2/大家畜单位。这表明,通过检测被采食特定种的茎直径,可以确定载畜量范围或调整放牧率。     

不同品种绵羊牧食行为的比较研究

试验在内蒙古锡林郭勒草原采用跟群放牧全日制观察法,研究了3个不同品种绵羊的牧食行为。结果表明,蒙古羊、德国肉用美利奴和双杂交绵羊的采食时间和游走时间差异显著(p<0.05),而站立时间和反刍卧息时间无显著差异(p>0.05),其它行为无明显差异(p>0.05)。3个不同品种绵羊对较柔软的(隐子草)和细嫩多汁的(灰绿藜)牧草适口性好,而对粗糙的牧草(针茅)采食较差。3个不同品种绵羊的单口采食量无显著差异(p>0.05),采食速度、采食量差异显著(p<0.05)。     

短花针茅草原放牧系统植物补偿性生长的研究：Ⅰ.植物净生长量

试验于１９９６￣１９９７年在内蒙古农牧学院哈雅教学牧场，研究２岁杂种羯羊在短花针茅荒漠草原不同载畜率下植物的净重复一。结果表明，１９９６年５个载畜率处理地上净生长量与对照区差异不显著（Ｐ〉０．０５），植物表现等补偿性生长。在１９９７年干旱年份，当载畜率小于２．０只羊／半年／ｈｍ＾２时，放牧区地上净生长量与对照间差异不显著（Ｐ〉０．０５），植物表现等补偿性生长。当载畜率大于２．０只羊／半年／ｈｍ＾２     

链烷技术估测典型草原不同放牧率绵羊食性食量方法研究

为了进一步探讨饱和链烷技术在典型草原自由放牧家畜中的应用,定量研究自由放牧绵羊食性及食量,于2004年6-9月在中国科学院内蒙古草原生态系统定位研究站放牧样地进行试验,选择体重及体况相近、健康无病的二岁羯羊(内蒙古细毛羊×蒙古羊)60只,按体重(36.9±2.6) kg聚类分组,设置6种放牧率(0,1.33,2.67,4.00,5.33和6.67羊/hm²)的轮牧实验,绵羊采食量的测定选择放牧率为1.33,4.00和6.67羊/hm²的处理,试验开始,每只羊投喂1粒QSM饱和链烷缓释胶囊。食性测定选用全部的放牧率进行,同时辅助全粪法、扣笼法一同评价。试验期内定期收集试验地牧草样品及绵羊粪便样品,使用气相色谱分析牧草和粪样中的链烷含量,应用链烷技术估测放牧绵羊的排粪量、牧草采食比例和干物质采食量。结果表明,植物链烷模式存在种间差异,运用链烷技术估测的排粪量和实际测得排粪量差异不显著(P>0.05),放牧绵羊主要采食7~9种牧草,且不同放牧季节不同放牧率绵羊采食的牧草种类和比例不同,但采食量差异不显著(P>0.05)。本研究表明,运用链烷技术结合扣笼方法可以估测天然草地自由放牧家畜牧草的采食比例、干物质采食量和排粪量。     

Grass species selection patterns on rotationally‐grazed Dohne Sourveld during autumn and early winter

Herbaceous species preference was studied during autumn and winter periods of occupation, on rotationally‐grazed Dohne Sourveld, at four different stocking rates. Only the most abundant grass species in the sward were monitored. Animals (cattle and sheep) grazed selectively (for plant species) during both autumn and winter, but the degree of selectivity increased in winter. Although animals could be forced to graze less selectively by increasing the stocking rate in autumn, stocking rate did not affect the sequence of species selection, but merely accelerated the process. Regrazing of tillers during grazing periods was a common occurrence in all but the heavy stocking rate treatment. Although Tristachya leucothrix was the most preferred species, the amount (mass) of this species that was grazed per unit basal tuft area was less than that of Themeda triandra.     

短花针茅荒漠草原植物群落特征对不同载畜率水平的响应

在内蒙古短花针茅荒漠草原采用5个载畜率水平绵羊放牧试验,研究植物群落对载畜率的响应.研究结果表明,主要植物盖度、高度和密度在低载畜率和中等载畜率下保持较高水平;中等载畜率有利于短花针茅生长;随着载畜率的增加,植物群落现存量下降;短花针茅草原适宜的载畜率为1.7～2只羊/hm2/半年.     

放牧率对绵羊体重及繁殖性能的影响

通过不同放牧率对内蒙古本地绵羊(母羊)连续2年(2008～2009)的体重和繁殖性能的影响的研究表明:(1)在试验期内,随着时间的推移,不同放牧率下的绵羊体重总体上都呈上升趋势;间隔1个放牧率或以上的处理间,存在不同程度的显著性差异;(2)绵羊的个体增重与放牧率之间存在负相关关系;而公顷增重与放牧率的关系符合二次曲线关系,在达到公顷最大增重前,随着放牧率的增大而增大,之后随着放牧率的增大减小;(3)单位家畜增重和单位面积增重的交点的生态学意义在于放牧率为1羊/hm2,公顷增重和家畜个体增重相同;单位家畜个体增重对应的畜产品最优放牧率为0.50羊/hm2,单位面积家畜最大增重对应的畜产品最优放牧率为2.38羊/hm2;(4)过高的放牧率导致绵羊出现空怀现象及产羔率下降;羔羊的初生重和个体增重均随着放牧率的增大而减小,但其显著性差异仅表现在较高的放牧率与较低的放牧率之间,而在相邻放牧率间差异不显著。     

Relationship of body condition score, live weight, stocking rate and grazing system to the mortality of Angora goats from hypothermia and their use in the assessment of welfare risks

Body condition scoring is widely used for sheep and cattle but the practice is included in only one Code of Practice for the welfare of goats in Australia. There is no published scientific evidence to support or defend its use in the assessment of welfare risks to farmed goats. PROCEDURE: The significance of stocking rate, grazing system, body condition score (CS) and live weight were investigated in explaining the risk of mortality of individual and flocks of grazing Angora goats from hypothermia following a severe weather event in April. This event occurred 5 weeks after shearing the goats. Angora goats and Saxon Merino sheep were grazed alone, or mixed together in equal numbers at each of three stocking rates. RESULTS: There was no mortality amongst Angora goats provided they grazed at the lowest stocking rate even when their CS was < or = 2.0. Mortality in flocks of Angora goats was most related to the CS reached during the preceding 2 months. For flocks of Angora goats there was no mortality at CS > or = 2.5 and mortality increased sharply at mean CS < 2.0. For individual Angora goats, mortality increased as CS declined and stocking rate and grazing combinations were additive in effect on mortality. Grazing with sheep increased mortality of Angora goats at higher stocking rates. The individual goat mortality rate was not dependent on individual plot effects suggesting that these results are applicable widely. Live weight loss was not related to mortality rates of goats once CS had been accounted for. CONCLUSION: It was concluded that CS and stocking rate were highly significant determinants of welfare risk in Angora goats.     

荒漠草原地区冷蒿构件及其动态规律对载畜率的响应

采用随机区组试验方法,研究了内蒙占高原荒漠草原地区不同载畜率对冷蒿构件数量特征的影响,结果表明:冷蒿生长时期和载畜率是影响冷蒿构件数量的关键因素,相同载畜率水平下,冷蒿的营养枝密度、不定根密度和匍匐茎长度为生长末期>生长盛期>生长初期,生殖枝8月最多,冷蒿生长盛期和末期,轻牧区的营养枝密度、不定根密度和匍匐茎长度显著增加(P<0.05);同一生长季节生殖枝随载畜率的增大显著下降(P<0.05),极度干旱的2005年没有形成生殖枝,说明干旱也是限制冷蒿生殖生长的关键性因子.荒漠草原地区冷蒿的繁殖格局以营养繁殖为主,占到80%以上,随载畜率的增加.冷蒿的营养枝分化率逐渐增加.     

Grassland Community Composition Response to Grazing Intensity Under Different Grazing Regimes

Grazing plays a key role in many ecosystems worldwide and can affect the structure and composition of terrestrial plant communities. Nonetheless, how grazing management, especially grazing regime (yearlong continuous and seasonal grazing), affects the relationship between grazing and vegetation on alpine grasslands has not been extensively studied. Here, we performed a grazing experiment in Gangcha county of Qinghai province of the Qinghai-Tibetan Plateau to test the effects of different stocking rates and grazing regimes on grassland biomass and plant structure and composition. Six stocking rates (ranging from 0 to 5.62 sheep ha^? 1) were used for continuous grazing, and three grazing intensities (1.72, 2.87, and 5.62 sheep ha^? 1) were used for seasonal grazing (grazed only in the growing season, from June to October) at the study sites. Plant biomass and grass functional community composition were characterized in two different yr (2011 and 2012). Additionally, species richness and plant diversity indexes were estimated to quantify the impacts of grazing on plant community composition. Our results indicated that grazing intensity best explained the plant biomass decrease in low-productivity environments, and different grazing regimes also influenced these results. The shifts in plant community structure and composition in response to increased grazing intensity differed considerably between continuous grazing and seasonal grazing. Seasonal grazing maintained greater amounts of palatable plant species, and fewer undesirable species in plant communities when compared with the composition after continuous grazing. Our results emphasize the importance of grazing regime in regulating the effects of grazing on plant communities and the importance of seasonal grazing for ecosystem maintenance, especially in the Qinghai-Tibetan Plateau. This suggests that periodic resting of grasslands could be a good management strategy to keep palatable species, thereby minimizing undesirable species in the overall species composition.     

不同放牧率对草原牧草再生性能和地上净初级生产力的影响

在生长季研究不同放牧率对草原牧草再生性能和地上净初级生产力的影响。结果表明,随着放牧率的增大,地上现存量呈线性下降,但地上净初级生产力(地上现存量＋家畜采食量)以2.67只羊/hm²处理最大,即存在超补偿性生长。地上最大现存量和最大净初级生产力出现的日期随着放牧率的增大有提前的趋势,二者随着放牧年限的延长均有较大幅度的下降。但降水可以缓和或加剧此变化的趋势。在冷蒿小禾草退化草原上,1.33和2.67只羊/hm²始牧时期为5月中下旬为宜,而重度放牧宜在6月上、中旬;重牧或过度放牧可降低牧草早期的再生能力,但可加快后期的再生速度,即后期牧草补偿性生长较明显。     

不同放牧率对草原植物与土壤C、N、P含量的影响

本文研究不同放牧率对草原植物土灌系统中C、N、P含量的影响。结果表明,对照区地上生物量和0～60m土层的总根量显著大于各放牧处理(P＜0.01),而放牧处理间差异不显著(P＞0.05)。对照区和1.33只羊/hm²处理植物的C含量显著大于4只羊/hm²和6.67只羊/hm²,而后两个处理的N、P含量较高。4只羊/hm²处理的C/N和C/P最小。6.67只羊/hm²处理已使根系和根系中的N素明显向表层聚集。对照区0～10cm土层土壤有机C含量显著大于各放牧处理,而各放牧处理间差异则不显著。土壤有机C,N含量与报系生物量成显著正相关。0～10cm土层中无机N在4只羊/hm²处理中最大。土壤微生物量C、P含量在6.67只羊/hm²处理中显著降低,其它处理间差异不显著。其中4只羊和6.67只羊/hm²处理的微生物N含量较高。