The addition of natural plant secondary compounds to ruminant feed has been extensively studied because of their ability to modify digestive and metabolic functions, resulting in a potential reduction in greenhouse gas emissions, among other benefits. Condensed tannin (CT) supplementation may alter ruminal fermentation and mitigate methane (CH4) emissions. This study’s objective was to determine the effect of quebracho CT extract [QT; Schinopsis quebracho-colorado (Schltdl.) F.A. Barkley & T. Meyer] within a roughage-based diet on ruminal digestibility and kinetic parameters by using the in situ and in vitro gas production techniques, in addition to blood urea nitrogen (BUN) and ruminal (volatile fatty acid [VFA], NH3-N, and protozoa count) parameters. Twenty rumen-cannulated steers were randomly assigned to four dietary treatments: QT at 0%, 1%, 2%, and 3% of dry matter (DM; QT0: 0% CT, QT1: 0.70% CT, QT2: 1.41% CT, and QT3: 2.13% CT). The in situ DM digestibility increased linearly (P = 0.048) as QT inclusion increased, whereas in situ neutral detergent fiber digestibility (NDFD) was not altered among treatments (P = 0.980). Neither total VFA concentration nor acetate-to-propionate ratio differed among dietary treatments (P = 0.470 and P = 0.873, respectively). However, QT3 had lower isovalerate and isobutyrate concentrations compared with QT0 (P ≤ 0.025). Ruminal NH3 and BUN tended to decline (P ≤ 0.075) in a linear fashion as QT inclusion increased, suggesting decreased deamination of feed protein. Ruminal protozoa count was reduced in quadratic fashion (P = 0.005) as QT inclusion increased, where QT1 and QT2 were lower compared with QT0 and QT3. Urinary N excretion tended to reduce in a linear fashion (P = 0.080) as QT increased. There was a treatment (TRT) × Day interaction for in vitro total gas production and fractional rate of gas production (P = 0.013 and P = 0.007, respectively), and in vitro NDFD tended to be greater for QT treatments compared with no QT inclusion (P = 0.077). There was a TRT × Day interaction (P = 0.001) on CH4 production, with QT3 having less CH4 production relative to QT0 on day 0 and QT2 on days 7 and 28. Feeding QT up to 3% of the dietary DM in a roughage-based diet did not sacrifice the overall DM digestibility and ruminal parameters over time. Still, it is unclear why QT2 did not follow the same pattern as in vitro gas parameters. Detailed evaluations of amino acid degradation might be required to fully define CT influences on ruminal fermentation parameters and CH4 production.

中文翻译：

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长期补充 quebracho 提取物对食用干草日粮的阉牛对消化、瘤胃和血液参数的影响

在反刍动物饲料中添加天然植物次生化合物已被广泛研究，因为它们能够改变消化和代谢功能，从而可能减少温室气体排放，以及其他好处。浓缩单宁 (CT) 补充剂可能会改变瘤胃发酵并减少甲烷 (CH4) 排放。本研究的目的是确定 quebracho CT 提取物 [QT; Schinopsis quebracho-colorado (Schltdl.) FA Barkley & T. Meyer] 除了血尿素氮 (BUN) 和瘤胃外，使用原位和体外产气技术在粗饲料日粮中研究瘤胃消化率和动力学参数（挥发性脂肪酸 [VFA]、NH3-N 和原生动物计数）参数。20 头瘤胃插管肉牛被随机分配到四种饮食处理：QT 为 0%，1%、2% 和 3% 的干物质（DM；QT0：0% CT，QT1：0.70% CT，QT2：1.41% CT 和 QT3：2.13% CT）。随着 QT 含量的增加，原位 DM 消化率线性增加（P = 0.048），而处理之间的原位中性洗涤纤维消化率（NDFD）没有改变（P = 0.980）。膳食处理之间的总 VFA 浓度和乙酸丙酸比均无差异（分别为 P = 0.470 和 P = 0.873）。然而，与 QT0 相比，QT3 的异戊酸和异丁酸浓度较低（P ≤ 0.025）。随着 QT 含量的增加，瘤胃 NH3 和 BUN 呈线性下降趋势（P ≤ 0.075），表明饲料蛋白的脱氨基作用降低。随着 QT 纳入增加，瘤胃原生动物数量以二次方方式减少 (P = 0.005)，其中 QT1 和 QT2 与 QT0 和 QT3 相比较低。随着 QT 的增加，尿 N 排泄趋于线性减少（P = 0.080）。体外总产气量和产气分数率存在治疗 (TRT) × 天相互作用（分别为 P = 0.013 和 P = 0.007），并且与不包含 QT 的治疗相比，QT 治疗的体外 NDFD 往往更大(P = 0.077)。CH4 产量存在 TRT × Day 交互作用 (P = 0.001)，QT3 在第 0 天相对于 QT0 和 QT2 在第 7 天和第 28 天具有较少的 CH4 产量。在粗饲料中饲喂高达 3% 的日粮 DM 的 QT -随着时间的推移，基于日粮的日粮并未牺牲整体 DM 消化率和瘤胃参数。尽管如此，尚不清楚为什么 QT2 没有遵循与体外气体参数相同的模式。