The objective of the study was to evaluate the effect of four levels of a commercial product based on quebracho that contains tannins (Table 1) on three types of diets: Feedlot, Dairy Cattle, and Grazing, using the in vitro gas production technique on ruminal fermentation, dry matter digestibility and methane (CH4) production to determine its potential use as a greenhouse gas mitigation strategy in ruminants. An in vitro trial was carried out in a completely randomized block design with a factorial arrangement of 4 [dose: 0, 0.25, 0.50, and 0.75 % of Protein Enhancer (PE)] x 3 [diet types: low (LFD), medium (MFD) and high forage (HFD)]. The fermentation of each treatment was carried out in triplicate in 120 mL amber antibiotic bottles, containing 0.5 g of substrate previously deposited in nylon bags (24 µm pore size) and 60 mL of a mixture of medium and rumen fluid from three Holstein cows. Incubations were replicated in two independent runs (blocks). The gas pressure (PSI) was recorded at 1, 2, 3, 6, 9, 12, 18, 24, 30, 36, 48, 60 and 72 hours of incubation. Gas pressure data were converted to gas volume (y = mL of gas; x = gas pressure PSI). Subsequently, pH was measured, and subsamples for analysis of volatile fatty acids (VFA) by gas chromatography were collected. Methane was analyzed with a Crowcon Gas-Pro detector, while ammoniacal nitrogen with a hybrid multimodal microplate reader. The data were analyzed with the MIXED procedure of SAS, and the comparison of means was analyzed with Tukey and with orthogonal polynomials for doses. An interaction (P < 0.05) was observed between diets and PE levels for CH4 concentration (%), where the diet with a greater level of forage and the greatest level of PE (0.75%), showed the least concentration (30%, P < 0.05) compared with the control diet of dairy cattle. On average, CH4 production [mL CH4/g dry matter (DM)] were 83.3, 63.6, and 35.3 for LFD, MFD, and HFD, respectively (Table 2). As the dose of PE increased, rumen pH and N-NH3decreased (P < 0.05), and the total VFA concentration increased (linear effect, P < 0.05; Table 3). Methane production was less (30%) with the grass-based diet and the greatest level of quebracho-based product with condensed tannins, compared with the dairy cattle diet with 0% condensed tannins. The diet for feedlot cattle was more digestible and, therefore, produced more gas and a greater concentration of CH4, in contrast to the grass-based diet, which produces less CH4. It is necessary to carry out in vivo trials, particularly in grazing cattle, to evaluate the effect of the quebracho-based product on performance and in vivo methane emission. This study was partially funded by PAPIIT-DGAPA-UNAM (grant IN212523).

中文翻译：

---

PSXII-29 单宁水平和饮食类型对体外瘤胃发酵和甲烷产生的影响


该研究的目的是评估含有单宁（表 1）的基于 quebracho 的四个水平的商业产品对三种饮食的影响：饲养场、奶牛和放牧，使用体外气体生产技术对瘤胃发酵、干物质消化率和甲烷 （CH4） 产生，以确定其作为反刍动物温室气体缓解策略的潜在用途。体外试验以完全随机的区组设计进行，析因安排为 4 [剂量：蛋白质增强剂 （PE） 的 0、0.25、0.50 和 0.75 %] x 3 [饮食类型：低 （LFD）、中 （MFD） 和高饲料 （HFD）]。每个处理的发酵在 120 mL 琥珀色抗生素瓶中一式三份进行，其中含有 0.5 g 先前沉积在尼龙袋（24 μm 孔径）中的 60 mL 培养基和瘤胃液混合物来自三头荷斯坦奶牛。孵育在两个独立的运行（块）中复制。在孵育的第 1 、 2 、 3 、 6 、 9 、 12 、 18 、 24 、 30 、 36 、 48 、 60 和 72 小时时记录气体压力 （PSI）。将气体压力数据转换为气体体积（y = mL 气体;x = 气体压力 PSI）。随后，测量 pH 值，并收集用于气相色谱分析挥发性脂肪酸 （VFA） 的子样品。使用 Crowcon Gas-Pro 检测器分析甲烷，而使用混合多模式酶标仪分析氨氮。使用 SAS 的 MIXED 程序分析数据，并使用 Tukey 和剂量的正交多项式分析均值比较。观察到日粮与 PE 水平之间的 CH4 浓度 （%） 之间存在交互作用 （P < 0.05），其中草料水平较高且 PE 水平最高 （0.75%） 的日粮浓度最低 （30%，P < 0.05） 与奶牛的对照饮食相比。平均而言，LFD、MFD 和 HFD 的 CH4 产生 [mL CH4/g 干物质 （DM）] 分别为 83.3、63.6 和 35.3（表 2）。随着 PE 剂量的增加，瘤胃 pH 和 N-NH3 降低 （P < 0.05），总 VFA 浓度增加 （线性效应，P < 0.05;表 3）。与单宁含量为 0% 的奶牛饮食相比，草基饮食和含有缩合单宁的 quebracho 产品产生的甲烷较少 （30%），并且含有缩合单宁的 quebracho 基产品含量最高。饲养场牛的日粮更容易消化，因此产生更多的气体和更高浓度的 CH4，而草基日粮产生的 CH4 较少。有必要进行体内试验，特别是在放牧的牛中，以评估基于 quebracho 的产品对性能和体内甲烷排放的影响。这项研究部分由 PAPIIT-DGAPA-UNAM （赠款 IN212523） 资助。