半胱胺在反刍动物营养中的作用/冯志华(河北农业大学中兽医学院 073000);龚建刚;刘现忠//河北畜牧兽医.-2004,20(10).-16~17,42半胱胺,又称β-巯基乙酸,相当于半胱胺酸的脱羧产物,是辅酶 A 分子的组成部分,是动物体内的生物活性物质,...半胱胺在反刍动物营养中的作用/冯志华(河北农业大学中兽医学院 073000);龚建刚;刘现忠//河北畜牧兽医.-2004,20(10).-16~17,42半胱胺,又称β-巯基乙酸,相当于半胱胺酸的脱羧产物,是辅酶 A 分子的组成部分,是动物体内的生物活性物质,在体内具有重要的生理作用。自 Szabo 等(1981)发现,半胱胺可以耗竭生长抑素以来,大量研究证实半胱胺(CS)展开更多
Rangelands occupy more than 80% of the agricultural land in Kyrgyzstan. At least 30% of Kyrgyz pasture areas are considered to be subject to vegetation and soil degradation. Since animal husbandry is the economic basi...Rangelands occupy more than 80% of the agricultural land in Kyrgyzstan. At least 30% of Kyrgyz pasture areas are considered to be subject to vegetation and soil degradation. Since animal husbandry is the economic basis to sustain people's livelihoods, rangeland degradation presents a threat for the majority of the population. We present for the first time an ecological assessment of different pasture types in a remote area of the Naryn Oblast, using vegetation and softs as indicators of rangeland conditions. We analysed the current degree of utilization (grazing pressure), the amount of biomass, soil samples, and vegetation data, using cluster analysis as well as ordination techniques. Winter pastures (kyshtoo) are characterized by higher pH values (average of 7.27) and lower organic matter contents (average of 12.83%) compared to summer pastures (dzailoo) with average pH values of 6.03 and average organic matter contents of 21.05%. Additionally, summer pastures show higher above- ground biomass, and higher species richness and diversity. Our results support the hypothesis that winter pastures, which are located near settlements, suffer from over-utilisation, while the more distant summer pastures are subjected to much lower grazing pressure,展开更多
Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau(TP)and elsewhere.However,there is a limited understanding of the effect...Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau(TP)and elsewhere.However,there is a limited understanding of the effects of grazing exclusion on alpine ecosystem functions and services and its impacts on herders’livelihoods.Our meta-analyses and questionnaire-based surveys revealed that grazing exclusion with fences was effective in promoting aboveground vegetation growth for up to four years in degraded alpine meadows and for up to eight years in the alpine steppes of the TP.Longer-term fencing did not bring any ecological and economic benefits.We also found that fencing hindered wildlife movement,increased grazing pressure in unfenced areas,lowered the satisfaction of herders,and rendered substantial financial costs to both regional and national governments.We recommend that traditional free grazing should be encouraged if applicable,short-term fencing(for 4-8 years)should be adopted in severely degraded grasslands,and fencing should be avoided in key wildlife habitat areas,especially the protected large mammal species.展开更多
The Bale Mountains of Ethiopia represent the world's largest continuous extent of afroalpine habitat. With a peak combined density of over 8000 individuals/km2, the endemic giant mole rat Tachyoryctes macrocephalus, ...The Bale Mountains of Ethiopia represent the world's largest continuous extent of afroalpine habitat. With a peak combined density of over 8000 individuals/km2, the endemic giant mole rat Tachyoryctes macrocephalus, Blick's grass rat Arvi- canthis blicki and the brush-furred mouse Lophuromys melanonyx are the dominant wild herbivores within this ecosystem and may be affected by the presence of high densities of domestic livestock. The purpose of this study was to establish whether these endemic rodent populations could respond to the removal of grazing pressure inside three 0.25 hectare livestock exclosures (paired with grazed control plots) and to determine whether such response was mediated through concomitant changes in the vegetation structure. We hypothesised that livestock grazing negatively affects endemic rodent populations through competition or increased predation risk and we predicted an increase in rodent biomass following the removal of grazing pressure. We found no evidence of rodent populations responding to the removal of livestock after fourteen months. The short-term nature of the ex- perimental design, environmental fluctuations and the ecosystem's inherent stochasticity may explain the apparent lack of a sig- nificant response. However, while this study is inconclusive, it emphasises the need for more long-term experimental investiga- tions to assess the effects of domestic grazers on vegetation and on dependent communities. The effects of rapidly increasing livestock numbers in the Bale Mountains will require continued close monitoring of vegetation and endemic animal communities as the afroalpine is altered by external biotic and abiotic forces .展开更多
基金funded by BMBF(Bundesministerium für Bildung und Forschung,Germany)(Ff E_IB-074)the context of the joint project TRANSPAST
文摘Rangelands occupy more than 80% of the agricultural land in Kyrgyzstan. At least 30% of Kyrgyz pasture areas are considered to be subject to vegetation and soil degradation. Since animal husbandry is the economic basis to sustain people's livelihoods, rangeland degradation presents a threat for the majority of the population. We present for the first time an ecological assessment of different pasture types in a remote area of the Naryn Oblast, using vegetation and softs as indicators of rangeland conditions. We analysed the current degree of utilization (grazing pressure), the amount of biomass, soil samples, and vegetation data, using cluster analysis as well as ordination techniques. Winter pastures (kyshtoo) are characterized by higher pH values (average of 7.27) and lower organic matter contents (average of 12.83%) compared to summer pastures (dzailoo) with average pH values of 6.03 and average organic matter contents of 21.05%. Additionally, summer pastures show higher above- ground biomass, and higher species richness and diversity. Our results support the hypothesis that winter pastures, which are located near settlements, suffer from over-utilisation, while the more distant summer pastures are subjected to much lower grazing pressure,
基金the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0405)the Science and Technology Service Network Initiative(KFJ-STS-QYZD060)+3 种基金the State Key Research Development Program of China(2016YFC0501802,2016YFC0501803 and 2016YFC0502002)the National Natural Science Foundation of China(41871040 and 41501057)the Innovative Research Team of the Ministry of Education of China(IRT_17R59)the Fundamental Research Funds for the Central Universities。
文摘Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau(TP)and elsewhere.However,there is a limited understanding of the effects of grazing exclusion on alpine ecosystem functions and services and its impacts on herders’livelihoods.Our meta-analyses and questionnaire-based surveys revealed that grazing exclusion with fences was effective in promoting aboveground vegetation growth for up to four years in degraded alpine meadows and for up to eight years in the alpine steppes of the TP.Longer-term fencing did not bring any ecological and economic benefits.We also found that fencing hindered wildlife movement,increased grazing pressure in unfenced areas,lowered the satisfaction of herders,and rendered substantial financial costs to both regional and national governments.We recommend that traditional free grazing should be encouraged if applicable,short-term fencing(for 4-8 years)should be adopted in severely degraded grasslands,and fencing should be avoided in key wildlife habitat areas,especially the protected large mammal species.
文摘The Bale Mountains of Ethiopia represent the world's largest continuous extent of afroalpine habitat. With a peak combined density of over 8000 individuals/km2, the endemic giant mole rat Tachyoryctes macrocephalus, Blick's grass rat Arvi- canthis blicki and the brush-furred mouse Lophuromys melanonyx are the dominant wild herbivores within this ecosystem and may be affected by the presence of high densities of domestic livestock. The purpose of this study was to establish whether these endemic rodent populations could respond to the removal of grazing pressure inside three 0.25 hectare livestock exclosures (paired with grazed control plots) and to determine whether such response was mediated through concomitant changes in the vegetation structure. We hypothesised that livestock grazing negatively affects endemic rodent populations through competition or increased predation risk and we predicted an increase in rodent biomass following the removal of grazing pressure. We found no evidence of rodent populations responding to the removal of livestock after fourteen months. The short-term nature of the ex- perimental design, environmental fluctuations and the ecosystem's inherent stochasticity may explain the apparent lack of a sig- nificant response. However, while this study is inconclusive, it emphasises the need for more long-term experimental investiga- tions to assess the effects of domestic grazers on vegetation and on dependent communities. The effects of rapidly increasing livestock numbers in the Bale Mountains will require continued close monitoring of vegetation and endemic animal communities as the afroalpine is altered by external biotic and abiotic forces .