Ruminant Nutrition and Anaerobe Laboratory, Department of Animal Science and Technology, Sunchon National University, Suncheon, South Korea.
Ruminant Nutrition and Anaerobe Laboratory, Department of Animal Science and Technology, Sunchon National University, Suncheon, South Korea.
Animal. 2024 Jun;18(6):101180. doi: 10.1016/j.animal.2024.101180. Epub 2024 May 8.
In recent years, the significant impact of ruminants on methane emissions has garnered international attention. While dietary strategies have been implemented to solve this issue, probiotics gained the attention of researchers due to their sustainability. However, it is challenging to ascertain their effectiveness as an extensive range of strains and doses have been reported in the literature. Hence, the objective of this experiment was to perform a meta-analysis of probiotic interventions aiming to reduce ruminal methane emissions from cattle. From 362 articles retrieved from scientific databases, 85 articles were assessed independently by two reviewers, and 20 articles representing 49 comparisons were found eligible for meta-analysis. In each study, data such as mean, SD, and sample sizes of both the control and probiotic intervention groups were extracted. The outcomes of interest were methane emission, methane yield, and methane intensity. For the meta-analysis, effect sizes were pooled using a fixed effect or a random effect model depending on the heterogeneity. Afterward, sensitivity analyses were conducted to confirm the robustness of the findings. Overall pooled standardized mean differences (SMDs) with their confidence intervals (CIs) did not detect significant differences in methane emission (SMD = -0.04; 95% CI = -0.18-0.11; P = 0.632), methane yield (SMD = -0.08; 95% CI = -0.24-0.07; P = 0.291), and methane intensity (SMD = -0.22; 95% CI = -0.50-0.07; P = 0.129) between cattle supplemented with probiotics and the control group. However, subgroup analyses revealed that multiple-strain bacterial probiotics (SMD = -0.36; 95% CI = -0.62 to -0.11; P = 0.005), specifically the combination of bacteria involved in reductive acetogenesis and propionate production (SMD = -0.71; 95% CI = -1.04 to -0.36; P = 0.001), emerged as better interventions. Likewise, crossbreeds (SMD = -0.48; 95% CI = -0.78 to -0.18; P = 0.001) exhibited a more favorable response to the treatments. Furthermore, meta-regression demonstrated that longer periods of supplementation led to significant reductions in methane emissions (P = 0.001), yield (P = 0.032), and intensity (P = 0.012) effect sizes. Overall, the results of the current study suggest that cattle responses to probiotic interventions are highly dependent on the probiotic category. Therefore, extended trials performed with probiotics containing multiple bacterial strains are showing the most promising results. Ideally, further trials focusing on the use of probiotics to reduce ruminal methane in cattle should be conducted to complete the available literature.
近年来，反刍动物对甲烷排放的重大影响引起了国际关注。虽然已经实施了饮食策略来解决这个问题，但由于其可持续性，益生菌引起了研究人员的关注。然而，确定其有效性具有挑战性，因为文献中报道了广泛的菌株和剂量。因此，本实验的目的是对旨在减少牛瘤胃甲烷排放的益生菌干预措施进行荟萃分析。从科学数据库中检索到的 362 篇文章中，由两位评审员独立评估了 85 篇文章，发现有 20 篇文章（代表 49 项比较）符合荟萃分析的条件。在每项研究中，都提取了对照组和益生菌干预组的平均值、标准差和样本量等数据。感兴趣的结果是甲烷排放、甲烷产量和甲烷强度。对于荟萃分析，根据异质性，使用固定效应或随机效应模型汇总效应大小。然后，进行敏感性分析以确认结果的稳健性。总体标准化均数差值（SMD）及其置信区间（CI）未检测到添加益生菌的牛与对照组之间在甲烷排放（SMD=-0.04；95%CI=-0.18-0.11；P=0.632）、甲烷产量（SMD=-0.08；95%CI=-0.24-0.07；P=0.291）和甲烷强度（SMD=-0.22；95%CI=-0.50-0.07；P=0.129）方面存在显著差异。然而，亚组分析表明，多菌株细菌益生菌（SMD=-0.36；95%CI=-0.62 至-0.11；P=0.005），特别是涉及还原乙酰生成和丙酸产生的细菌的组合（SMD=-0.71；95%CI=-1.04 至-0.36；P=0.001），是更好的干预措施。同样，杂种（SMD=-0.48；95%CI=-0.78 至-0.18；P=0.001）对治疗的反应更为有利。此外，元回归表明，更长时间的补充会导致甲烷排放（P=0.001）、产量（P=0.032）和强度（P=0.012）效应大小的显著降低。总体而言，本研究的结果表明，牛对益生菌干预的反应高度取决于益生菌类别。因此，含有多种细菌菌株的益生菌的扩展试验显示出最有希望的结果。理想情况下，应进行进一步的试验，重点关注使用益生菌来减少牛瘤胃中的甲烷，以完善现有文献。
