1 Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands.
Animal. 2013 Dec;7(12):1950-8. doi: 10.1017/S1751731113001766.
Medium-chain fatty acids (MCFA), for example, capric acid (C10:0), myristic (C14:0) and lauric (C12:0) acid, have been suggested to decrease rumen archaeal abundance and protozoal numbers. This study aimed to compare the effect of MCFA, either supplied through krabok (KO) or coconut (CO) oil, on rumen fermentation, protozoal counts and archaeal abundance, as well as their diversity and functional organization. KO contains similar amounts of C12:0 as CO (420 and 458 g/kg FA, respectively), but has a higher proportion of C14:0 (464 v. 205 g/kg FA, respectively). Treatments contained 35 g supplemental fat per kg DM: a control diet with tallow (T); a diet with supplemental CO; and a diet with supplemental KO. A 4th treatment consisted of a diet with similar amounts of MCFA (i.e. C10:0+C12:0+C14:0) from CO and KO. To ensure isolipidic diets, extra tallow was supplied in the latter treatment (KO+T). Eight fistulated bulls (two bulls per treatment), fed a total mixed ration predominantly based on cassava chips, rice straw, tomato pomace, rice bran and soybean meal (1.5% of BW), were used. Both KO and CO increased the rumen volatile fatty acids, in particular propionate and decreased acetate proportions. Protozoal numbers were reduced through the supplementation of an MCFA source (CO, KO and KO+T), with the strongest reduction by KO. Quantitative real-time polymerase chain reaction assays based on archaeal primers showed a decrease in abundance of Archaea when supplementing with KO and KO+T compared with T and CO. The denaturing gradient gel electrophoresis profiles of the rumen archaeal population did not result in a grouping of treatments. Richness indices were calculated from the number of DGGE bands, whereas community organization was assessed from the Pareto-Lorenz evenness curves on the basis of DGGE band intensities. KO supplementation (KO and KO+T treatments) increased richness and evenness within the archaeal community. Further research including methane measurements and productive animals should elucidate whether KO could be used as a dietary methane mitigation strategy.
中链脂肪酸（MCFA），例如癸酸（C10：0）、肉豆蔻酸（C14：0）和月桂酸（C12：0），已被提议减少瘤胃古菌的丰度和原生动物的数量。本研究旨在比较 MCFA 的效果，无论是通过 krabok（KO）还是椰子（CO）油提供，对瘤胃发酵、原生动物计数和古菌丰度以及它们的多样性和功能组织的影响。KO 中 C12：0 的含量与 CO 相似（分别为 420 和 458 g/kg FA），但 C14：0 的比例更高（分别为 464 v. 205 g/kg FA）。处理组每公斤 DM 添加 35 克补充脂肪：对照日粮含牛脂（T）；添加 CO 的日粮；和添加 KO 的日粮。第 4 种处理由来自 CO 和 KO 的等量 MCFA（即 C10：0+C12：0+C14：0）组成。为了确保等脂饮食，在后者中添加额外的牛脂（KO+T）。8 头瘘管公牛（每种处理 2 头公牛），以木薯片、稻草、番茄渣、米糠和豆粕为主的全混合日粮（占体重的 1.5%）。KO 和 CO 均增加了瘤胃挥发性脂肪酸，特别是丙酸，并降低了乙酸比例。通过添加 MCFA 源（CO、KO 和 KO+T）减少了原生动物的数量，其中 KO 的减少最为明显。基于古菌引物的定量实时聚合酶链反应检测显示，与 T 和 CO 相比，添加 KO 和 KO+T 时古菌丰度降低。瘤胃古菌种群的变性梯度凝胶电泳图谱并未导致处理分组。丰富度指数是根据 DGGE 带的数量计算的，而群落组织是根据 DGGE 带强度的 Pareto-Lorenz 均匀度曲线评估的。KO 补充（KO 和 KO+T 处理）增加了古菌群落的丰富度和均匀度。包括甲烷测量和生产动物在内的进一步研究应阐明 KO 是否可作为一种膳食甲烷缓解策略。
