Rumen acidosis is a common metabolic disorder occurring when organic acid production exceeds clearance capacity, reducing ruminal pH. The occurrence of acidosis has been directly correlated to the ratio of concentrate to forage in the diet. However, rates of substrate fermentation and acid absorption vary at different locations in the reticulo-rumen. The objective of this study was to determine the pH and redox potential (Eh) in different locations of the reticulo-rumen using 16 ruminally cannulated steers (309 ± 43 kg) receiving different supplementation levels of quebracho extract (QT; Schinopsis balansae) within a grower type diet (CP: 13.4%; total digestible nutrients [TDN]: 70.4%; and ME: 2.55 Mcal/kg, dry matter [DM] basis). Animals were randomly assigned to one of four dietary treatments: QT at 0%, 1%, 2%, and 3% of DM (QT0, QT1, QT2, and QT3, respectively), containing about 0%, 0.7%, 1.4%, and 2.1% of condensed tannins (CT), DM basis, respectively. Animals were adapted to the basal diet for 12 d before being introduced to predetermined treatments for 4 weeks (wk), with diets provided twice daily to allow ad libitum intake. Weekly measurements of ruminal fluid pH and Eh were taken 4 h post-feeding using a portable pH meter with two probes (pH and redox) in four locations of the reticulo-rumen (reticulum, cranial sac, dorsal sac, and ventral sac). Data were analyzed using a random coefficients model with the pen as a random effect and wk as repeated measures, with DM intake included as a covariate. There was no interaction among treatments, location, and wk (P ≥ 0.882) on reticulo-ruminal pH. Overall, ruminal pH was lower for QT0 and QT1 compared to QT3 (P < 0.001). The pH in the reticulum was greater than those of the ventral and dorsal sacs (6.05 vs. 5.94, 5.89, respectively; P ≤ 0.001) but similar to cranial sac (6.00). Reticular pH was positively correlated with the ruminal locations (≥0.78; P < 0.001). The linear equation to estimate ruminal mean pH using reticulum pH had an intercept and slope different from zero (P ≤ 0.04), but CT (% DM) was not different from zero (P = 0.15), root mean square error of 0.15, and R2 of 0.778: 0.723 (±0.36) + 0.857 (±0.059) × reticulum pH + 0.033 (±0.023) × CT. The Eh was lower for QT0 in week 1 than all other treatments (P < 0.001). We concluded that reticulo-ruminal pH differs among locations in the rumen regardless of QT supplementation level and days on feed, with reticular pH being the highest.

中文翻译：

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技术说明：添加不同水平的 quebracho 提取物的生长肉牛网状瘤胃不同位置的 pH 值和氧化还原电位的比较

瘤胃酸中毒是一种常见的代谢紊乱，当有机酸产生超过清除能力时，会降低瘤胃的 pH 值。酸中毒的发生与日粮中精料与草料的比例直接相关。然而，底物发酵和酸吸收的速率在网瘤胃的不同位置不同。本研究的目的是使用 16 头瘤胃插管阉牛 (309 ± 43 kg) 确定网状瘤胃不同位置的 pH 值和氧化还原电位 (Eh)，这些阉牛接受不同补充水平的白藜芦醇提取物 (QT; Schinopsis balansae)。生长型日粮（CP：13.4%；总可消化营养素 [TDN]：70.4%；和 ME：2.55 Mcal/kg，基于干物质 [DM]）。动物被随机分配到四种饮食治疗中的一种：0%、1%、2% 和 3% DM 的 QT（QT0、QT1、QT2、和 QT3)，分别含有约 0%、0.7%、1.4% 和 2.1% 的缩合单宁 (CT)，DM ​​基础。动物适应基础饮食 12 天，然后引入预定治疗 4 周 (wk)，每天提供两次饮食以允许随意摄入。每周测量瘤胃液 pH 值和 Eh 的时间是在饲喂后 4 小时，使用便携式 pH 计在网状瘤胃的四个位置（网状瘤、颅囊、背囊和腹囊）有两个探针（pH 和氧化还原）。使用随机系数模型分析数据，将笔作为随机效应，将 wk 作为重复测量，将 DM 摄入量作为协变量。处理、位置和周（P ≥ 0.882）对网状瘤胃 pH 值没有交互作用。总体而言，与 QT3 相比，QT0 和 QT1 的瘤胃 pH 值较低（P < 0.001）。网状结构的 pH 值高于腹囊和背囊（分别为 6.05 和 5.94、5.89；P ≤ 0.001），但与颅囊相似（6.00）。网状 pH 值与瘤胃位置呈正相关（≥0.78；P < 0.001）。使用网状 pH 估计瘤胃平均 pH 的线性方程的截距和斜率不为零 (P ≤ 0.04)，但 CT (% DM) 不为零 (P = 0.15)，均方根误差为 0.15，并且R2 为 0.778：0.723 (±0.36) + 0.857 (±0.059) × 网状 pH + 0.033 (±0.023) × CT。第 1 周 QT0 的 Eh 低于所有其他治疗（P < 0.001）。我们得出结论，无论 QT 补充水平和饲喂天数如何，瘤胃不同位置的网状瘤胃 pH 值不同，其中网状瘤胃 pH 值最高。