Aims This in vitro study aimed to examine the effect of proportions of Leucaena (Leucaena leucocephala (Lam.) de Wit) to Napier grass (Pennisetum purpureum Schumach) or levels of corn oil (CO) and their interaction on ruminal fermentation, methane (CH4) production and fatty acid profile. Methods The experiment was conducted as a 4 × 3 factorial arrangement following a completely randomised design with two factors. The treatments were according to the proportion of Leucaena and Napier grass (in g/kg DM, Treatment (T)1 = 0 : 750 (control), T2 = 250 : 500, T3 = 500 : 250, T4 = 750 : 0). Three levels of CO (in mg rumen fluid, CO1 = 0, CO2 = 10, CO3 = 20 respectively) were added to each of the diet, giving a total 12 dietary treatments. Key results Replacing Napier grass with Leucaena at 500 g/kg (T3) and 750 g/kg (T4) levels increased the molar volatile fatty acid concentration, microbial protein synthesis (P 0.05). Conclusion This study demonstrated that the inclusion of Leucaena into a Napier grass-based diet at 500 g/kg and 750 g/kg DM positively affected rumen fermentation, reduced CH4 formation and increased beneficial fatty acids in the rumen. Although CO had similar positive effects on CH4 production and targeted beneficial fatty acids, it reduced the microbial protein synthesis at inclusion of 20 mg/mL DM. Overall, there were synergistic interactions between Leucaena and CO in reducing CH4 production and improving the fatty acid profile in the rumen. Implications It is possible to improve animal productivity while reducing the environmental impact of livestock production through inclusion of tannin-containing Leucaena and CO in ruminant diets in tropical regions where C4 grasses typically have low nutritive value.

中文翻译：

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银合欢和玉米油对瘤胃发酵、甲烷产生和脂肪酸谱的影响：一项体外研究

目的 这项体外研究旨在检查银合欢 (Leucaena leucocephala (Lam.) de Wit) 与纳皮尔草 (Pennisetum purpureum Schumach) 的比例或玉米油 (CO) 水平的影响及其对瘤胃发酵、甲烷 (CH4 ) 生产和脂肪酸谱。方法 实验按照 4 × 3 的因子排列进行，遵循具有两个因子的完全随机设计。处理根据银合欢和纳皮尔草的比例（g/kg DM，处理（T）1 = 0 : 750（对照），T2 = 250 : 500，T3 = 500 : 250，T4 = 750 : 0） . 将三种水平的 CO（以毫克瘤胃液计，分别为 CO1 = 0、CO2 = 10、CO3 = 20）添加到每种饮食中，总共进行 12 次饮食处理。主要结果 用 500 g/kg (T3) 和 750 g/kg (T4) 水平的银合欢替代 Napier 草增加了摩尔挥发性脂肪酸浓度，微生物蛋白质合成 (P 0.05)。结论 本研究表明，将银合欢以 500 g/kg 和 750 g/kg DM 加入 Napier 草基饲料对瘤胃发酵产生积极影响，减少 CH4 形成并增加瘤胃中的有益脂肪酸。尽管 CO 对 CH4 产生和靶向有益脂肪酸具有类似的积极影响，但它在包含 20 mg/mL DM 时减少了微生物蛋白质的合成。总体而言，银合欢和 CO 之间在减少 CH4 产生和改善瘤胃中的脂肪酸谱方面存在协同相互作用。