The relationship between feed intake at production levels and enteric CH4 production in ruminants consuming forage-based diets is well described and considered to be strongly linear. Unlike temperate grazing systems, the intake of ruminants in rain-fed tropical systems is typically below maintenance requirements for part of the year (dry seasons). The relationship between CH4 production and feed intake in animals fed well below maintenance is unexplored, but changes in key digestive parameters in animals fed at low levels suggest that this relationship may be altered. We conducted a study using Boran yearling steers (n 12; live weight: 162·3 kg) in a 4 × 4 Latin square design to assess the effect of moderate to severe undernutrition on apparent digestibility, rumen turnover and enteric CH4 production of cattle consuming a tropical forage diet. We concluded that while production of CH4 decreased (1133·3–65·0 g CH4/d; P < 0·0001), over the range of feeding from about 1·0 to 0·4 maintenance energy requirement, both CH4 yield (29·0−31·2 g CH4/kg DM intake; P < 0·001) and CH4 conversion factor (Ym 9·1–10·1 MJ CH4/MJ gross energy intake; P < 0·01) increased as intake fell and postulate that this may be attributable to changes in nutrient partitioning. We suggest there is a case for revising emission factors of ruminants where there are seasonal nutritional deficits and both environmental and financial benefits for improved feeding of animals under nutritional stress.

中文翻译：

---

严重低于维持的采食量会增加牛肠道发酵产生的甲烷产量

生产水平的采食量与肠道 CH 之间的关系4以草料为基础的饮食的反刍动物的产量得到了很好的描述，并被认为是强线性的。与温带放牧系统不同，雨养热带系统中反刍动物的摄入量通常低于一年中部分时间（旱季）的维护要求。CH之间的关系4饲喂远低于维持水平的动物的产量和采食量尚未研究，但低水平饲喂动物的关键消化参数的变化表明这种关系可能会改变。我们使用 Boran 一岁公牛进行了一项研究（n12; 活重：162·3 kg)，采用 4 × 4 拉丁方设计，以评估中度至重度营养不良对表观消化率、瘤胃周转率和肠道 CH 的影响4生产食用热带草料的牛。我们得出结论，虽然生产 CH4减少 (1133·3–65·0 g CH4/d;磷< 0·0001)，在从大约 1·0 到 0·4 维持能量需求的喂养范围内，两者都是 CH4产率 (29·0−31·2 g CH4/kg 干物质摄入量；磷< 0·001) 和 CH4转换系数 (是米9·1–10·1 MJ CH4/MJ 总能量摄入；磷< 0·01) 随着摄入量的下降而增加，并假设这可能是由于营养分配的变化。我们建议在存在季节性营养不足的情况下修改反刍动物的排放因子，并为改善营养压力下动物的喂养带来环境和经济利益。