Department of Animal Sciences, The Ohio State University, Columbus, OH 42310, USA.
J Dairy Sci. 2013 Mar;96(3):1782-92. doi: 10.3168/jds.2012-6159. Epub 2013 Jan 16.
Coconut (CO) and fish (FO) oils were previously shown to inhibit rumen methanogenesis and biohydrogenation, which mitigates methane emission and helps improve beneficial fatty acids in meat and milk. This study aimed at investigating the comparative effects of CO and FO on the methanogenesis, fermentation, and microbial abundances and diversity in vitro rumen cultures containing different doses (0, 3.1, and 6.2 mL/L) of each oil and 400mg feed substrate using rumen fluid from lactating dairy cows as inocula. Increasing doses of CO and FO quadratically decreased concentrations of methane, but hydrogen concentrations were only increased quadratically by CO. Both oils linearly decreased dry matter and neutral detergent fiber digestibility of feeds but did not affect the concentration of total volatile fatty acids. However, CO reduced acetate percentage and acetate to propionate ratio and increased the percentages of propionate and butyrate to a greater extent than FO. Ammonia concentration was greater for CO than FO. As determined by quantitative real-time PCR, FO had greater inhibition to methanogens than CO, but the opposite was true for protozoal, Ruminococcus flavefaciens, and Fibrobacter succinogenes. Ruminococcus albus was not affected by either oil. Denaturing gradient gel electrophoresis (DGGE) profiles revealed that bacterial and archaeal community composition were changed differently by oil type. Based on Pareto-Lorenz evenness curve analysis of the DGGE profiles, CO noticeably changed the functional organization of archaea compared with FO. In conclusion, although both CO and FO decreased methane concentrations to a similar extent, the mode of reduction and the effect on abundances and diversity of archaeal and bacterial populations differed between the oils. Thus, the use of combination of CO and FO at a low dose may additively lower methanogenesis in the rumen while having little adverse effect on rumen fermentation.
椰子油（CO）和鱼油（FO）先前已被证明可抑制瘤胃甲烷生成和生物氢化作用，从而减少甲烷排放，并有助于改善肉和奶中的有益脂肪酸。本研究旨在探讨 CO 和 FO 对体外瘤胃培养物中甲烷生成、发酵、微生物丰度和多样性的比较影响，这些培养物含有不同剂量（0、3.1 和 6.2 mL/L）的每种油和 400mg 饲料底物，使用泌乳奶牛的瘤胃液作为接种物。CO 和 FO 的剂量增加均使甲烷浓度呈二次降低，但 CO 仅使氢浓度呈二次增加。两种油均线性降低了饲料的干物质和中性洗涤纤维消化率，但不影响总挥发性脂肪酸的浓度。然而，CO 降低了乙酸的百分比和乙酸与丙酸的比例，而丙酸和丁酸的百分比增加幅度大于 FO。CO 的氨浓度大于 FO。通过定量实时 PCR 测定，FO 对产甲烷菌的抑制作用大于 CO，但相反，对原生动物、黄色瘤胃球菌和纤维丁酸弧菌的抑制作用则相反。CO 对 Ruminococcus albus 没有影响。变性梯度凝胶电泳（DGGE）图谱显示，油的类型对细菌和古菌群落组成的影响不同。基于 DGGE 图谱的 Pareto-Lorenz 均匀度曲线分析，CO 明显改变了古菌的功能组织，与 FO 相比。总之，尽管 CO 和 FO 都将甲烷浓度降低到相似的程度，但减少的模式以及对古菌和细菌种群丰度和多样性的影响在两种油之间有所不同。因此，在低剂量下同时使用 CO 和 FO 可能会在瘤胃中额外降低甲烷生成，而对瘤胃发酵几乎没有不良影响。
