State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Beijing Key Laboratory for Dairy Cow Nutrition, Beijing University of Agriculture, Beijing 102206, China.
J Dairy Sci. 2021 Mar;104(3):2924-2934. doi: 10.3168/jds.2020-18974. Epub 2021 Jan 15.
We evaluated the effects of propylene glycol (PG) on in vitro ruminal fermentation, methanogenesis, and microbial community structure. A completely randomized design was conducted in the in vitro incubation, and 4 culture PG dose levels (0, 7.5, 15, and 22.5 μL/g of dry matter) were used in the trial. Based on the fermentation results, the control group (0 μL/g of dry matter, CON) and the second treatment group (15.0 μL/g of dry matter, TRT) were chosen for further analysis to explore the effects of PG on the bacterial and archaeal community structure. The concentrations of propanol, propanal, and succinate increased linearly, whereas the concentration of l-lactate decreased linearly as PG doses increased. The molar proportion of propionate demonstrated a linear increase with increasing PG doses. In contrast with propionate, the molar proportion of acetate and butyrate, and acetate-to-propionate ratio decreased linearly with increasing PG doses. The addition of PG markedly decreased methane production without negative effects on nutrient degradability. In the archaeal level, the relative abundance of Methanobrevibacter tended to decrease, but that of Methanomassiliicoccus significantly increased in TRT group. At the bacterial level, the relative abundance of Bacteroidetes and Prevotella in TRT group was numerically higher than that in CON group. The analysis of the Negativicutes class showed that the relative abundance of Succiniclasticum tended to increase, whereas that of Selenomonas tended to decrease in TRT group. These results demonstrated that PG might be used as an inhibitor to mitigate methane emission. However, the small decrease in methane production will limit the application of PG as a methane inhibitor in production practices. Further research is needed to determine whether use together with other inhibitors may improve the effects of PG on the utilization of reducing equivalents ([H]) and methane production.
我们评估了丙二醇（PG）对体外瘤胃发酵、甲烷生成和微生物群落结构的影响。采用完全随机设计进行体外孵育试验，试验设置 4 个培养 PG 剂量水平（0、7.5、15 和 22.5 μL/g 干物质）。基于发酵结果，选择对照组（0 μL/g 干物质，CON）和第二处理组（15.0 μL/g 干物质，TRT）进行进一步分析，以探讨 PG 对细菌和古菌群落结构的影响。丙醇、丙醛和琥珀酸的浓度呈线性增加，而随着 PG 剂量的增加，L-乳酸的浓度呈线性下降。丙酸摩尔比例随 PG 剂量的增加呈线性增加。与丙酸相反，随着 PG 剂量的增加，乙酸和丁酸的摩尔比例以及乙酸/丙酸比呈线性下降。添加 PG 可显著减少甲烷生成，但对养分降解率没有负面影响。在古菌水平上，Methanobrevibacter 的相对丰度趋于下降，但在 TRT 组中 Methanomassiliicoccus 的相对丰度显著增加。在细菌水平上，TRT 组的拟杆菌门和普雷沃氏菌的相对丰度数值高于 CON 组。Negativicutes 类的分析表明，Succiniclasticum 的相对丰度趋于增加，而 Selenomonas 的相对丰度趋于减少在 TRT 组中。这些结果表明 PG 可作为一种抑制剂来减轻甲烷排放。然而，甲烷产量的小幅下降将限制 PG 作为生产实践中甲烷抑制剂的应用。需要进一步研究以确定与其他抑制剂一起使用是否可以提高 PG 对还原当量（[H]）和甲烷生成利用的效果。
