Gradients in fracture force and grazing resistance across canopy layers in seven tropical grass species
Gradients in fracture force and grazing resistance across canopy layers in seven tropical grass species
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DOI：
10.1111/j.1365-2494.2012.00900.x
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发表时间：
2013-06
影响因子：
2.4
通讯作者：
A. Jacobs;J. Scheper;M. Benvenutti;I. Gordon;D. Poppi;A. Elgersma
中科院分区：
文献类型：
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作者：
A. Jacobs;J. Scheper;M. Benvenutti;I. Gordon;D. Poppi;A. Elgersma
在繁殖田中，茎可以充当影响反刍牲畜放牧行为的屏障。茎的屏障效应与折断茎所需的力和这些茎的密度（两者结合起来构成放牧阻力）密切相关，在预测放牧繁殖牧场的反刍动物的草料摄入量时需要考虑这些因素。人们认为不同草种的草地冠层之间的放牧阻力差异会影响咬合尺寸，但数据很少。在这项研究中，我们评估了七种热带草种的三个冠层的放牧阻力。每个冠层的物种在耐牧性方面存在显着差异，耐牧性的一般排名顺序按升序排列：Cenchrus ciliaris（“美洲”buffel）、Digitaria milanjiana（“Jarra”手指草）、Setaria Surgs（一年生鸽子草）、Setaria sphacelata（“Narok”狗尾草）、Dichanthium sericeum（昆士兰早熟禾）、Chloris gayana（‘Callide’罗德草）。在冠层顶部，放牧阻力似乎并未对任何物种造成障碍，但在冠层底部，却对所有物种造成了障碍。不同物种的断裂力和密度对耐放牧性的相对贡献也不同。结果强调了管理放牧系统以尽量减少茎的屏障效应的重要性，这可以通过控制牧场的物候阶段以及系统中使用的草种和动物大小来实现。
In reproductive swards, stems can act as a barrier that affects the grazing behaviour of ruminant livestock. The barrier effect of stems is closely associated with both the force required to fracture the stems and the density of these stems (in combination, these make up grazing resistance), and these factors need to be considered when making predictions about the forage intake of ruminants grazing reproductive pastures. Differences in grazing resistance between sward canopy layers of different grass species are thought to affect bite dimensions, but data are scarce. In this study, we assessed the grazing resistance for three canopy layers of seven tropical grass species. Species differed significantly in grazing resistance for every canopy layer, with a general ranking order for grazing resistance, in ascending order: Cenchrus ciliaris (‘American' buffel), Digitaria milanjiana (‘Jarra’ finger grass), Setaria surgens (annual pigeon grass), Setaria sphacelata (‘Narok’ setaria), Dichanthium sericeum (Queensland bluegrass), Chloris gayana (‘Callide’ Rhodes grass). In the top canopy layer, grazing resistance did not appear to create a barrier for any of the species, but in the bottom canopy layer, it did for all species. Species also differed in the relative contribution of fracture force and density to grazing resistance. The results highlight the importance of managing the grazing systems to minimize the barrier effect of the stems, which can be done by controlling the phenological stage of the pasture and the grass species and animal size used in the system.