Plant-based strategies towards minimising 'livestock's long shadow'
Plant-based strategies towards minimising 'livestock's long shadow'
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DOI：
10.1017/s0029665110001953
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发表时间：
2010-11-01
影响因子：
7
通讯作者：
Abberton, Michael
中科院分区：
文献类型：
--
作者：
Kingston-Smith, Alison H.;Edwards, Joan E.;Abberton, Michael
反刍动物养殖是人类食物链的重要组成部分。反刍动物可以通过与瘤胃中不同微生物种群的相互作用，利用不适合种植谷类作物的土地的排泄物。瘤胃是用于木质纤维素消化的连续流动发酵器，其中微生物蛋白质和发酵终产物由动物直接或在瘤胃后消化期间并入。然而，瘤胃发酵在捕获呈现的营养资源方面效率低下，导致环境污染和温室气体的产生。瘤胃发酵会产生甲烷，饲料氮的滞留不良会造成水和土地的氮污染，并导致一氧化二氮的产生。一个可能的原因是瘤胃微生物的膳食基质供应不平衡。产氨细菌对氨基酸的脱氨作用释放出氨，氨可被瘤胃细菌同化并用于微生物蛋白质合成。然而，当碳水化合物受到限制时，微生物生长缓慢，这意味着微生物蛋白质合成和过量排泄对氨的需求较低。因此，可以通过增加饲料中易发酵糖的可用性或通过与植物次级产物络合使蛋白质不能用于蛋白水解来提高蛋白质利用率。或者，放牧牛摄取活细胞的认识已经导致发现植物细胞由于暴露于瘤胃条件而经历内源性、应激介导的蛋白质降解。这提供了一个机会，通过使用减少蛋白质水解作为选择工具，用于开发改良的牧草品种，以减少畜牧业对环境的影响。
Ruminant farming is an important component of the human food chain. Ruminants can use offtake from land unsuitable for cereal crop cultivation via interaction with the diverse microbial population in their rumens. The rumen is a continuous flow fermenter for the digestion of ligno-cellulose, with microbial protein and fermentation end-products incorporated by the animal directly or during post-ruminal digestion. However, ruminal fermentation is inefficient in capturing the nutrient resource presented, resulting in environmental pollution and generation of greenhouse gases. Methane is generated as a consequence of ruminal fermentation and poor retention of ingested forage nitrogen causes nitrogenous pollution of water and land and contributes to the generation of nitrous oxide. One possible cause is the imbalanced provision of dietary substrates to the rumen micro-organisms. Deamination of amino acids by ammonia-producing bacteria liberates ammonia which can be assimilated by the rumen bacteria and used for microbial protein synthesis. However, when carbohydrate is limiting, microbial growth is slow, meaning low demand for ammonia for microbial protein synthesis and excretion of the excess. Protein utilisation can therefore be improved by increasing the availability of readily fermentable sugars in forage or by making protein unavailable for proteolysis through complexing with plant secondary products. Alternatively, realisation that grazing cattle ingest living cells has led to the discovery that plant cells undergo endogenous, stress-mediated protein degradation due to the exposure to rumen conditions. This presents the opportunity to decrease the environmental impact of livestock farming by using decreased proteolysis as a selection tool for the development of improved pasture grass varieties.