Department of Animal Science, Oklahoma State University, Stillwater, OK 74078, USA.
J Anim Sci. 2012 Aug;90(8):2794-801. doi: 10.2527/jas.2011-4407. Epub 2012 Mar 9.
The objective of this experiment was to determine if ruminal temperature rise coincides with pH reduction using an acidosis challenge model. Twelve ruminally cannulated steers (518 ± 28 kg BW) were administered ruminal temperature-monitoring devices that recorded temperature every 2 min. Steers were fed a 63% concentrate diet at 1.6% BW for 20 d before being randomly assigned to 1 of 3 acidosis challenge treatments: no dietary change (CON), one-half of daily DMI replaced with cracked corn (HALF), or all of daily DMI replaced with cracked corn (CORN). The challenge was initiated by ruminally dosing steers with their treatment diets. Ruminal pH and rectal temperatures (T(rec)) were recorded every 3 h for 72 h. All steers were offered CON diets at 24 and 48 h after challenge. Ruminal pH showed a treatment × day effect (P = 0.01). Ruminal pH of CORN steers was lower (P = 0.03) than that of HALF steers on d 1, was lower (P ≤ 0.004) than that of HALF and CON steers on d 2, and tended to be lower (P ≤ 0.10) than that of HALF and CON steers on d 3. Treatment did not affect (P ≥ 0.42) RecT. Ruminal temperature (T(rum)) showed a treatment · d(-1) · h(-1) after feeding interaction (P < 0.01). At 3 h after challenge, T(rum) of CORN and HALF steers was higher (P ≤ 0.01) than that of CON steers. On d 2, T(rum) of CORN steers was higher (P ≤ 0.03) than that of CON between 6 and 12 h after feeding. From 15 to 21 h after feeding on d 2, T(rum) of HALF steers was higher (P < 0.01) than that of CORN and CON steers. On d 3, at the time of feeding until 3 h later, T(rum) of CORN steers was lower (P ≤ 0.04) than that of all other steers. Rectal temperature was correlated (P ≤ 0.01) with T(rum) on all days for CON and CORN steers. Ruminal pH was negatively correlated (P ≤ 0.04) with T(rec) on d 2 and T(rum) on d 1 in CORN steers, and T(rum) was negatively correlated (P ≤ 0.02) with ruminal pH in HALF and CON steers on d 1 and 3, respectively. The amount of time above T(rum) of 39.0°C or 39.45°C was correlated (P ≤ 0.05) with the time spent below a ruminal pH of 5.5 in CORN steers; however, time above T(rum) of 39.0°C did not differ (P = 0.87) among treatments. Results indicate that there is a negative relationship between T(rum) and ruminal pH during an acidotic episode; therefore, T(rum) monitoring can detect a potential acidotic episode.
本实验的目的是确定在酸中毒挑战模型中，瘤胃温度升高是否与 pH 值降低同时发生。12 头瘤胃插管的阉牛（518±28kgBW）接受了瘤胃温度监测设备的监测，该设备每 2 分钟记录一次温度。在接受 1.6%BW 的 63%浓缩日粮 20d 之前，这些牛被随机分配到 3 种酸中毒挑战处理之一：不改变日粮（CON）、用粉碎玉米替代一半的日采食量（HALF）或用粉碎玉米替代全部日采食量（CORN）。通过瘤胃内给药启动挑战，每头牛接受其处理日粮。在 72h 内每 3h 记录瘤胃 pH 和直肠温度（Trec）。在挑战后 24 和 48h 为所有牛提供 CON 日粮。瘤胃 pH 存在处理×天效应（P=0.01）。在第 1d，CORN 牛的瘤胃 pH 低于 HALF 牛（P=0.03），在第 2d，CORN 牛的瘤胃 pH 低于 HALF 和 CON 牛（P≤0.004），在第 3d，CORN 牛的瘤胃 pH 低于 HALF 和 CON 牛（P≤0.10）。处理不影响（P≥0.42）RecT。在进食后，瘤胃温度（Trum）表现出处理·d(-1)·h(-1)的交互作用（P＜0.01）。在挑战后 3h，CORN 和 HALF 牛的 Trum 高于 CON 牛（P≤0.01）。在第 2d，在 6-12h 后，CORN 牛的 Trum 高于 CON 牛（P≤0.03）。在第 2d，在 15-21h 后，HALF 牛的 Trum 高于 CORN 和 CON 牛（P＜0.01）。在第 3d，在进食时到 3h 后，CORN 牛的 Trum 低于所有其他牛（P≤0.04）。在 CON 和 CORN 牛的所有日子，直肠温度与 Trum 之间均呈正相关（P≤0.01）。在第 2d，在 CORN 牛中，瘤胃 pH 与 TreC 呈负相关（P≤0.04），在第 1d，与 Trum 呈负相关（P≤0.02），在第 3d，与 Trum 呈负相关（P≤0.02），在 HALF 和 CON 牛中，与 Trum 呈负相关。高于 39.0°C 或 39.45°C 的时间与 CORN 牛瘤胃 pH 低于 5.5 的时间呈正相关（P≤0.05）；然而，在 39.0°C 以上的时间在处理之间没有差异（P=0.87）。结果表明，在酸中毒发作期间，Trum 与瘤胃 pH 之间存在负相关；因此，Trum 监测可以检测潜在的酸中毒发作。
