Despite tropical grasses being the main feed source for major part of ruminant livestock, information about nutritional quality changes under climate changes scenario are still scarce. The novelty of this work was to determine the effects of season and elevated CO2 under field conditions upon biomass production and nutritional value of Brachiaria decumbens during 2 years. The Free-Air Carbon Dioxide Enrichment was established in twelve rings: six of them being the control (current atmosphere) and others six fumigated with pure CO2 to achieve a higher concentration (e[CO2]). In each ring, two 0.25 m2 plots have been established with B. decumbens and after standardization cut, green forage yield was evaluated frequently. Plant samples were collected at 20 cm height and evaluated for determining the biomass production, nutritive value and in vitro enteric methane (CH4) production. Season and year had significant effect (P 0.05). Overall, e[CO2] and rainfall seasons significantly increased forage production, contributing to sequester carbon in plant biomass, but this C4 tropical grass must be grazed at its best protein and fermentable carbohydrate ratio for advantages in the rumen microbial synthesis and lowering CH4 production intensity of the production system.

中文翻译：

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Brachiaria spp. 的营养价值和肠道甲烷产量。低于高 [CO2]

尽管热带草是大部分反刍牲畜的主要饲料来源，但关于气候变化情景下营养质量变化的信息仍然很少。这项工作的新颖之处在于确定了在田间条件下季节和 CO2 升高对 2 年内卧床臂菌的生物量生产和营养价值的影响。自由空气二氧化碳富集建立在十二个环中：其中六个是对照（当前大气），其他六个用纯 CO2 熏蒸以达到更高的浓度 (e[CO2])。在每个环中，已经建立了两个 0.25 m2 的地块，种植 B. decumbens，在标准化切割后，经常评估青草产量。在 20 厘米高处收集植物样品并评估以确定生物量产量，营养价值和体外肠内甲烷 (CH4) 生产。季节和年份有显着影响（P<0.05）。总体而言，e[CO2] 和降雨季节显着增加了牧草产量，有助于隔离植物生物量中的碳，但这种 C4 热带草必须以其最佳蛋白质和可发酵碳水化合物比例放牧，以便在瘤胃微生物合成和降低 CH4 生产强度方面发挥优势的生产系统。