The aim of the trial was to evaluate the effect of dietary additions of Stevia rebaudiana Bertoni extract (SB) and Chestnut wood tannin (CWT) on the in vitro rumen fermentability, protozoal population and methane yield. Both plant products were tested at 3 different levels of inclusion (0.75, 1.50 and 3.00% of incubated dry matter, DM) in a total mixed ration (TMR) for ruminants by using rumen batch culture systems and a rumen inoculum collected from sheep. Total volatile fatty acid concentration, their proportions and gas production were not modified by the plant extracts inclusion, except a significant linear increment of gas production at 24 hr for SB (p = .049). Ammonia concentration decreased (p < .05) of about 17% when 1.50 or 3.00% of CWT were included into TMR. Rumen protozoa population was depressed by the SB inclusion (p = .002) with a maximum reduction of 40% at the highest SB dosage, whereas CWT negatively affected total protozoa counts (−19%) only at the dose of 3.00%. In vitro DM and NDF degradability were not affected by the supplementation of SB and CWT, as well as the methane yield. Thus, the addition of SB and CWT decreases the in vitro protozoa population of the rumen with different intensity and without effects on fermentation parameters, apart from a reduction of nitrogen degradability caused by CWT. Despite the effect on protozoa, no decreasing effect on methane production was detected.

中文翻译：

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在膳食中补充栗木中的单宁或甜叶菊提取物，并对瘤胃体外发酵，原生动物数量和甲烷产生产生影响。

该试验的目的是评估日粮甜叶菊提取物（SB）和栗木单宁（CWT）对体外瘤胃发酵能力，原生动物种群和甲烷产量的影响。通过使用瘤胃分批培养系统和从绵羊收集的瘤胃接种物，以总混合定量（TMR）对两种植物产品进行了3种不同含量的包涵体测试（总干物质混合比（TMR）为0.75、1.50和3.00％DM）。除植物提取物外，总挥发性脂肪酸浓度，其比例和产气量均未改变，只是SB在24 h产气量线性显着增加（p  = .049）。氨浓度降低（p 当将1.50或3.00％的CWT包含在TMR中时，约<17％（约​​<.05）。瘤胃原生动物种群被SB所抑制（p  = 0.002），在最高SB剂量下最大减少40％，而CWT仅在3.00％剂量下对总原生动物计数产生负面影响（−19％）。SB和CWT的补充以及甲烷的收率不影响DM和NDF的体外降解性。因此，除了降低CWT引起的氮降解能力外，SB和CWT的添加还降低了瘤胃体外原生动物种群的强度，并且对发酵参数没有影响。尽管对原生动物有影响，但未检测到对甲烷产生的减少影响。