放牧绵羊牧食行为及采食量研究

在锡林郭勒草原对三种放牧绵羊(蒙古羊、引种羊、杂种羊)进行不同月份的牧食行为观察及采食量测定,结果表明:放牧绵羊9月份的采食时间比例均高于8月份;沙质草地放牧绵羊的采食和游走时间比例低于高平原草地;蒙古羊、引种羊和杂种羊沙质草地的平均采食量分别为1.15kg/d、1.60kg/d和1.35kg/d,高平原草地为1.56kg/d、1.82kg/d和1.71kg/d,分别相差0.41kg/d、0.22kg/d和0.36kg/d。     

放牧绵羊牧食行为与生产性能的研究

该试验在内蒙古锡林郭勒草原沙质草地放牧条件下,分别对4月龄和6月龄杂种羊、引种羊和蒙古羊的牧食行为、生产性能以及羊肉品质进行了比较研究,并探讨了年龄对绵羊生产性能与肉品质的影响。     

Feed Intake and Performance of Sheep Grazing Semiarid Grassland in Response to Different Grazing Systems

Effects of grazing management systems (GS) on biomass production and nutritional quality of rangeland vegetation in semiarid regions are extensively studied; however, limited information is available regarding their effects on diet digestibility and feed intake of grazing livestock. We therefore analyzed digestibility of ingested organic matter (dOM), organic matter intake (OMI), and live weight gain (LWG) of sheep in a grazing experiment established in the Inner Mongolian steppe of China, where two GS were tested for six different grazing intensities (GI) from very light to heavy grazing. For the continuous grazing system, sheep grazed the same plots each year, and for the alternating system, grazing and hay making were alternated annually between two adjacent plots. In July, August, and September 2009 and 2010, feed intake and live weight of sheep were determined. The GS did not affect dOM (P = 0.101), OMI (P = 0.381), and LWG of sheep (P = 0.701). Across both GS LWG decreased from 98 g · d^-1 for GI1 to 62 g · d^-1 for GI6 (P &spilt; 0.001; R² = 0.42). There were no interactions between GS and GI for all measured parameters (P ≥ 0.061), indicating that alternating grazing did not compensate for negative effects of heavy grazing even after 4 yr of grassland use. In summary, our study showed that irrespective of GI, alternating grassland use does not improve dOM, OMI, and hence, LWG of sheep. However, it might enhance revenues and ecological sustainability in the long term when compared to the common practice of continuous grazing at very high stocking rates.     

Assessment of Expert Opinion: Seasonal Sheep Preference and Plant Response to Grazing

Expert opinion was sought on 2 issues relating to herbivory: seasonal sheep preferences for plant species and seasonal plant response to grazing. Expert opinion is commonly used to parameterize models: it is therefore important to assess its quality. Understanding the limitations of expert knowledge can allow prioritization of future research. Nine experts in plant or grazing ecology from Scotland/Northern England were individually interviewed. The experts ranked sheep preferences for species in 4 rangeland vegetation types and provided categorical information on plant response to grazing. For both issues, seasonal information was collected. Uncertainty (unanswered questions) on plant responses was much higher than uncertainty on sheep preferences. Uncertainty on sheep preference was significantly negatively correlated with plant species commonness, but not with quantity of scientific literature. Uncertainty on plant responses was significantly negatively correlated with both plant commonness and literature. There was agreement among experts on sheep preferences; standardized seasonal information for selected plant species is presented. In general, experts considered graminoids to be preferred over dwarf shrubs, with forbs and other species groups intermediate. Seasonal variation in sheep preference was greater for heath and mire than for grasslands. There was limited agreement among experts on seasonal plant responses. Some experts considered grazing in summer to affect growth more than grazing in winter, whereas others thought season had little effect. Sufficient agreement was found at the species level to present results on plant responses. Experts considered graminoids more resilient to grazing than dwarf shrubs. Experts agreed on sheep preference at different times of year, and on the overall resilience of plant species to grazing. However, the experts held 2 paradigms on the impact of seasonal grazing. Further research is required to explore this, because seasonal grazing regimes are currently promoted as conservation management tools.     

US Sheep Industry and the Public Grazing Fee

Since the mid-1940s US sheep inventory has experienced dramatic declines, which has weakened the sheep industry significantly, making it increasingly important to analyze potential policy implications that could affect US sheep inventories in the future. Public grazing lands are often used in sheep production, especially within the western United States. The public grazing fee is, therefore, a cost within the production of sheep. A US sheep model applying capital stock inventory accounting methodology is developed to model both the supply and demand within the joint sheep and wool industries. The model is used to create a baseline projection for the next several years. Various public grazing fee policies are created to demonstrate the effects of the policies on the levels of sheep inventory and sheep and wool production within the country. Results indicate removing the public grazing fee (set at $0/animal unit month) may slow the rate of decline but would not be effective at reversing the declining trend. This suggests reducing the public grazing fee is not a viable policy option to help bring stability to the sheep and wool industries. However, projections indicate raising the grazing fee would have a substantial adverse effect on the industries. Consideration should be given to these results as grazing fee policy is adjusted moving forward.     

绵羊生产系统对不同放牧制度的响应

在1990～1997年定量放牧基础上,分别就绵羊生产性能对放牧率的反应、草-畜互作关系对放牧管理方式的响应、不同放牧制度对绵羊食性的影响、放牧绵羊的食量与营养需要进行了论述.     

Spotted Knapweed Utilization by Sequential Cattle and Sheep Grazing

Prescribed (or targeted) sheep grazing can effectively suppress the invasive perennial forb spotted knapweed (Centaurea stoebe L. ssp. micranthos [Gugler] Hayek). Some ranchers and other natural resource managers, however, resist using this weed management tool over concerns that sheep may consume too much of the graminoid standing crop, thereby decreasing its availability to cattle and wildlife and possibly harming graminoids with excessive defoliation. One potential approach to address these concerns is to graze spotted knapweed infestations first with cattle, immediately followed by sheep. We evaluated this sequential grazing strategy on foothill rangeland in western Montana, comparing sequential grazing at a moderate stocking rate in mid June (spotted knapweed in bolting stage) vs. mid July (spotted knapweed in late-bud/early flowering stage). Pastures (0.81 ha) were grazed with three yearling cattle for 7 d, immediately followed with 7 d of grazing by seven yearling sheep. Combined relative (i.e., utilization) of graminoids by cattle and sheep averaged 40% in June and July, safely within sustainable grazing use levels recommended for the site. Combined relative use of spotted knapweed by cattle and sheep also did not differ between June and July, averaging 62%. Previous research indicates that this degree of use is sufficient to suppress spotted knapweed. Our results indicate that prescribed sheep grazing can be applied immediately following cattle grazing in either June or July to suppress spotted knapweed without overusing desirable graminoids. Cattle and sheep will eat less graminoids and more spotted knapweed if cattle and sheep graze sequentially when spotted knapweed is in its late-bud/early flowering stage (mid July) rather than its bolting stage (mid June).     

两种放牧制度下的牧草营养价值及绵羊对营养的摄食

对比分析了在短花针茅荒漠草原划区轮牧与连续放牧2种放牧制度下草地牧草营养及绵羊对牧草营养的摄食情况.结果表明划区轮牧草地牧草生产力较高,且能够提供较多的牧草营养;在牧草供应充足时,连续放牧绵羊能够摄入营养物质含量较高的牧草,但牧草短缺时,由于采食量的不足,会导致家畜摄入营养的不足.     

高寒牧区放牧条件下萨福克羊与藏羊杂交效果研究

在海北高寒地区放牧条件下进行了萨福克羊与藏羊的杂交试验。结果表明:萨藏F1的断奶体重高于藏羊(P<0.05),8月龄体重显著高于藏羊(P<0.01);体高、体长、胸围、胸宽、胸深、尻宽和管围显著高于藏羊(P<0.01)。8月龄屠宰测定表明,萨杂F1的宰前活重、胴体重和净肉重分别为27.55kg,12.13kg和9.47kg均显著高于藏羊(P<0.01),屠宰率为44.03%,胴体净肉率为78.07%,眼肌面积为10.75cm2,GR值为13.33mm,骨肉比为1.0∶3.55,均优于藏羊。杂种羊产肉性能和肉用品质显著提高,杂种优势明显。     

高寒牧区放牧条件下萨福克羊与藏羊杂交效果研究

在海北高寒地区放牧条件下进行了萨福克羊与藏羊的杂交试验.结果表明萨藏F1的断奶体重高于藏羊(P<0.05),8月龄体重显著高于藏羊(P<0.01);体高、体长、胸围、胸宽、胸深、尻宽和管围显著高于藏羊(P<0.01).8月龄屠宰测定表明,萨杂F1的宰前活重、胴体重和净肉重分别为27.55 kg, 12.13 kg和9.47 kg均显著高于藏羊(P<0.01),屠宰率为44.03%,胴体净肉率为78.07%,眼肌面积为10.75 cm2, GR值为13.33 mm,骨肉比为1.0∶3.55,均优于藏羊.杂种羊产肉性能和肉用品质显著提高,杂种优势明显.     

滩羊放牧行为及营养生态的研究

本文研究了滩羊在宁夏盐池干草原夏季草场上的放牧行为及放牧营养生态。结果表明，同一般的绵羊相比，滩羊在放牧行为上既有相似之处，又有其独特的方面。成年滩羊和当年断奶羔羊的日平均采食速率分别为５３．５口／分和４１．２口／分，日平均采食干物质量分别为１．５１ｋｇ和０．７９ｋｇ。成年滩羊的日平均游走、采食、卧息和反刍时间分别为１４９．１、４０８．０、１０和２．５分，日平均饮水量达６．６８土１．５１ｋｇ／只。成年滩羊和当年断奶羔羊均存在着营养供应不平衡，除粗蛋白摄入量较高外，其能量、钙和磷的摄入量均不足。本文建议，随着滩羊放牧环境日趋干旱、沙化和退化，对于草原草场上放牧的滩羊在夏季进行适当的能量和矿物质饲料补饲，仍然是一分必要的。     

Sheep and Goat Grazing Effects on Three Atlantic Heathland Types

Heathlands in the northwest of Spain have been traditionally used by domestic herbivores as a food resource. However, their abandonment in the past decades has promoted a high incidence of wildfires, threatening biodiversity. Sheep and goats exhibit different grazing behavior, affecting rangelands dynamics in a different way, but the botanical and structural composition may also affect such dynamics. The aim of this article was to compare the grazing effects of sheep and goats on three different heathland types: previously burned grass- or gorse (Ulex gallii Planchon)-dominated and unburned heather (Erica spp.)-dominated shrublands. Two grazing treatments (sheep or goats) were applied in each vegetation type in a factorial design with two replicates (12 experimental plots). A small fenced area was excluded from grazing in each plot (control treatment). The experiment was carried out from 2003 to 2006, and the grazing season extended from May to October–November. Plant cover, canopy height, and phytomass amount and composition were assessed in each plot. Results showed that goats controlled shrub encroachment, phytomass accumulation, and canopy height more than sheep in either burned grass– and gorse– and unburned heather–dominated shrublands. It was accompanied by a higher increase of herbaceous species under goat grazing. Nevertheless, plant dynamics showed different trends between the three vegetation types studied. Grazing effects were more important in previously burned grass-dominated heathlands than in unburned heather-dominated shrublands. At the end of the experiment (May 2006), shrub cover, height, and woody phytomass were significantly higher in the ungrazed enclosures than in the grazed plots. Small ruminant grazing, especially with goats, is proposed as an efficient tool to reduce shrub encroachment and woody phytomass accumulation in heathlands, thus reducing fire hazard, although these grazing effects depend on heathland composition.     

放牧条件下白萨福克羊与藏绵羊杂交效果分析

为了提高藏绵羊的生产性能,利用白萨福克羊与藏绵羊进行杂交,测定了白-藏F1代羊和藏绵羊的各年龄段的体重体尺指标、屠宰性能、产肉性能及肉质指标等。结果表明:白-藏F1代公、母羊的初生重、6月龄体重、12月龄体重和日增重均有极显著提高(P<0. 01),6～12月龄日增重相对0～6月龄日增重有所下降;初生重、6月龄体重和0～6月龄日增重极显著高于藏绵羊(P<0. 01); 6月龄时体高、体长、胸围、管围都有所增加(P>0. 05),胸围增大最明显(P<0. 01); 12月龄体高、体长、胸围和管围均比母本藏绵羊有显著增加(P<0. 01)。白-藏F1代羊与藏绵羊相比,胴体重提高12. 36%,净肉重提高13. 28%,净肉率提高6. 02%,屠宰率提高7. 50%,差异均显著(P<0. 05); GR值高于藏绵羊,差异极显著(P<0. 01)。     

中国北方放牧绵羊硒的营养状况和季节变化

通过对我国４省区１５个牧场３００只放牧绵羊血浆和粪硒含量的采集和分析发现，在全年的部分时间，甘肃省的各个牧场和新疆的巩乃斯羊场均存在着硒的供给不足。此种现象在夏季和秋季表现最为明显，而此时动物和牧草生长最快。此时若不给予适量的硒，很容易使动物产生硒缺乏。对羔羊尤其需要引起注意，即使在夏季草场放牧时，也需给羔羊补硒     

放牧对赖草群落生物量及植物多样性的影响

通过对围封5年与自由放牧的赖草（Leymus secalinus）群落进行整个生长季的生物量和物种多样性动态观测,旨在了解放牧对赖草群落的影响。结果表明：整个生长季围栏内外赖草始终占据主导地位,放牧样地物种丰富度指数显著高于围封样地（P<0.05）,多样性指数和均匀度指数在不同时期变化趋势不同;赖草群落地上生物量、高度、盖度、物种丰富度、多样性指数和均匀度指数在整个生长季均表现为先增加后降低,放牧显著降低群落地上生物量（P<0.05）,在整个生长季放牧使群落盖度平均降低31.82%,群落高度平均降低36.37 cm;围封样地群落地下生物量在7月和9月出现2个峰值,分别为4148.4 和4359.27 g·m^-2,放牧样地地下生物量在8月达到最大,为2559.28 g·m^-2;群落地下生物量随土层深度的增加所占比例逐渐减小,其中围封和放牧样地0~30 cm土层所占比例分别为75.64%和77.37%。适度放牧有利于促进赖草群落的物种多样性,不合理放牧降低草地植物群落的盖度、高度和生物量,因此围栏封育能够促进赖草草地的稳定和可持续发展。     

人工草地绵羊放牧与割草综合利用的研究

通过放牧试验，对决定畜牧业生产效率的放牧管理体系的主要因子（绵羊品种，载畜量和放牧制度）进行评价和研究。结果表明，适合于红地池坝工人草地的放牧绵羊品种为内蒙古中国美利奴羊，放牧方法为划区轮牧；载畜量为７．５个绵羊单位／公顷，各个牧草和长阶段的放牧强度主：＝１７９．５＋５．４８Ｘ（Ｘ为牧草生长速度）放牧小工面积，割草小区面积与机动小区面积的百分比组成为６６．７：２０：１３．３，不适放牧起止时间为：一     

牦牛和藏羊混合放牧对放牧家畜采食量和植物补偿性生长的影响

为探究放牧方式对青藏高原高寒草地家畜的采食量和植物补偿生长的影响,本试验在环青海湖流域高寒草地设置放牧方式（牦牛单独放牧、藏羊单独放牧、牦牛和藏羊1：2混牧、牦牛和藏羊1：4混牧、牦牛和藏羊1：6混牧）控制试验,以期确定草地的承载力,并为制定合理的草地管理措施提供依据。试验结果表明：在群落水平上,家畜的采食量在藏羊（Ovis aries）单独放牧以及牦牛（Bos grunniens）与藏羊1：2混牧方式下,显著高于其他方式（P<0.05）;在功能群水平上,藏羊单独放牧与牦牛和藏羊1：2混牧这2种放牧方式下家畜对豆科植物的采食量较高;藏羊单独放牧与牦牛和藏羊1：2混牧植物的补偿生长能力显著高于其他放牧方式（P<0.05）。研究表明：藏羊单独放牧时,其采食量最高;牦牛和藏羊1：2混牧的放牧方式对植物补偿性生长的促进作用最明显。因此,从放牧家畜采食量与植物补偿生长两方面考虑,在青藏高原高寒草地藏羊单独放牧与牦牛和藏羊1：2混牧的放牧方式较为合理。