Impacts of silica-based defences in grasses on the feeding preferences of sheep
Impacts of silica-based defences in grasses on the feeding preferences of sheep
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DOI：
10.1016/j.baae.2009.04.004
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发表时间：
2009-01-01
影响因子：
3.8
通讯作者：
Hartley, Sue E.
中科院分区：
文献类型：
--
作者：
Massey, Fergus P.;Massey, Kate;Hartley, Sue E.
牧草是许多陆地生态系统的主体，维持着高密度的食草哺乳动物，因此具有重要的经济和生态意义。传统上，草被认为是适应于容忍放牧，而不是抵御放牧;然而，最近发现，沉积在草叶子中的二氧化硅对无脊椎食草动物和小型哺乳动物起着捕食威慑作用。这项研究评估二氧化硅是否是有效的喂养威慑较大的哺乳动物食草动物。我们评估的影响，操纵二氧化硅水平在五个草种内和草species.Sheep之间的摄食偏好是由种间差异的适口性。因此，在一个单一的物种二氧化硅除了没有引起显着的变化，摄食偏好。然而，有显着差异的摄食偏好和咬率之间的草种，这些差异更为显着时，草已暴露于高水平的二氧化硅。二氧化硅对偏好的影响在可口的物种（如早熟禾）中最不明显，而在不太可口的物种（如羽叶短柄草和羊茅）中最不明显。绵羊喂养更长的时间，采取了更多的叮咬，并有较高的咬率的草种与最低的叶片二氧化硅浓度，即P. annua.Sheep的影响较小的硅防御比小，非反刍类草食动物，但物种偏好排名的变化所造成的二氧化硅表明，它可能会导致草地组成的变化。此外，在适口性已经相对较低的物种中，二氧化硅诱导的咬合率降低可能会降低饲料摄入率，从而影响绵羊的生产性能。(c)2009 Gesellschaft fur Okologie.由爱思唯尔有限公司出版。All rights reserved.
Grasses, which dominate many terrestrial ecosystems, sustain high densities of grazing mammals, so are of great economic and ecological importance. Traditionally, grasses are thought to be adapted to tolerate grazing rather than defend against it; however, silica deposited in the leaves of grasses has recently been shown to act as a feeding deterrent to invertebrate herbivores and small mammals. This study assesses whether silica is effective as a feeding deterrent to larger mammalian herbivores. We assess the impact of manipulated silica levels in five grass species on the feeding preferences of sheep both within and between grass species.Sheep feeding behaviour was driven by between-species differences in palatability. Hence, within a single species silica addition did not cause significant changes in feeding preference. However, there were significant differences in both the feeding preferences and bite rates between grass species, and these differences were much more marked when the grasses had been exposed to high levels of silica. The impacts that silica had on preference were least pronounced in palatable species (e.g. Poa annua) compared with less-palatable species (e.g. Brachypodium pinnatum and Festuca ovina). Sheep fed for longer, took more bites and had a higher bite rate on the grass species with the lowest leaf silica concentrations, namely P. annua.Sheep were less affected by silica defences than smaller, non-ruminant herbivores, but the changes in species preference rankings caused by silica suggest it may lead to changes in sward composition. Further, in species that are already relatively low in palatability, silica-induced reductions in bite rate could potentially reduce forage intake rates, with consequences for sheep performance. (c) 2009 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.