摘要
An active dry yeast (ADY) supplement (Vistacell, AB Vista, UK) was proposed to favorably influence ruminal parameters of heat loaded cattle. Eight British-cross steers (365 ± 27 kg) were fed a 90% concentrate diet (1.8% of BW intake, DM basis) and supplemented with either ADY (3.0 g/d; providing 6 × 1010CFU/d) or no yeast (0.0 g/d; CON) for 14 d. Rumen boli were inserted through the esophagus on d 0 for continuous monitoring of pH and rumen temperature. On d 13 and 14, steers were housed in an open circuit calorimetry chamber for 48 h in either thermoneutral (TN) (18 ± 0.55 C; 35% RH) or heat loaded (HL) (35 ± 0.55 C; 35% RH) temperature. After 48 h, rumen fluid (500 mL) was extracted via esophageal pump and immediately processed for further analysis and in vitro fermentation using a 2×2 factorial arrangement with the in vitro gas production technique (IVGP). The IVGP revealed an effect of ADY on DMD versus CON (61.7% vs 32.8%,P= 0.031) but there was no effect of temperature. No effects were observed on the fermentation dynamics of the DM. There was a significant interaction of supplement and temperature on estimated ME in which ADY+TN, CON+HS, and ADY+HL were greater (P= 0.0307) than CON+TN (2.97, 2.84, 2.72 vs 1.95 Mcal/kg, respectively). The IVGP of methane (CH4) g/L or CH4g/L/g of DM digested was not affected. Mean rumen pH of steers tended to be affected by temperature and supplement: HL steers had lower pH than TN (P= 0.064), and CON steers had lower pH than ADY (P= 0.077). Time spent below pH of 6 was affected by supplement: ADY was much less than CON (390.0 vs 882.5 min/d,P= 0.05). Time spent below pH of 5.0 was affected by temperature: TN was much less than HL (1.75 vs 590.75 min/d,P= 0.034, respectively). Mean rumen temperature and time spent above 40 C was affected by temperature but not by supplement. As expected HL steers had greater rumen temperature and spent more time above 40 C than TN steers (40.51 vs 39.21 C,P= 0.0165; 1,216.25 vs 27.5 min/d,P= 0.002). Our results indicated that supplementation of 3.0 g/d of an ADY in the diets of steers consuming 90% concentrate diets under severe heat loads may increase DMD, increase available ME, and relieve subacute ruminal acidosis.
摘要译文
一种活性干酵母（ADY）补充剂（Vistacell，AB Vista，UK）被提议有利地影响热负荷牛的瘤胃参数。八只英国交叉阉牛（365±27公斤）以90％浓缩饲料（体重摄入量的1.8％，DM基础）喂养，并补充ADY（3.0 g / d;提供6×10 10 10 / CFU / d）或无酵母（0。0克/天; CON）14天。在第0天通过食管插入瘤胃粉末以连续监测pH和瘤胃温度。在第13和14天，在热中性（TN）（18±0.55C; 35％RH）或热负荷（HL）（35±0.55C; 35％RH）温度下，将阉牛犊放置在开路量热室中48小时。 48小时后，（500mL）通过食管泵提取并且立即用体外气体生产技术（IVGP）使用2×2因子排列进行进一步分析和体外发酵。IVGP显示ADY对DMD和CON的影响（61.7％比32.8％，P \x3d 0.031），但没有影响温度。没有观察到DM的发酵动力学的影响。补充剂和温度与CON + TN（2.97,2.84,2.72 vs 1.95 Mcal / kg）相比，ADY + TN，CON + HS和ADY + HL更高（P \x3d 0.0307）分别）。甲烷（CH 4）g / L或CH 4 g / L / g DM消化的IVGP不受影响。转向的平均瘤胃pH趋向于受温度和补充的影响：HL转向的pH低于TN（P \x3d 0.064），CON转向的pH低于ADY（P \x3d 0.077）。pH值低于6的时间受补充剂影响：ADY远低于CON（390.0比882.5 min / d，P \x3d 0.05）。 pH值低于5.0的时间受温度的影响：TN远低于HL（1。75对590.75分钟/天，分别为P \x3d 0.034）。平均瘤胃温度和40摄氏度以上的时间受温度影响，但不补充。正如预期的那样，HL steers具有更高的瘤胃温度，并且花费了比TN steers更高的40℃以上的时间（40.51 vs 39.21 C，P \x3d 0.0165; 1,216.25 vs 27.5 min / d，P \x3d 0.002）。我们的研究结果表明，在严重热负荷下消耗90％精料日粮的阉牛日粮中补充3.0 g / d ADY可能会增加DMD，增加可用ME，并缓解亚急性瘤胃酸中毒。
W. L. Crossland;A. B. Norris;T. R. Callaway;L. O. Tedeschi. 565 Effects of heat load and active dry yeast supplementation on ruminal parameters[J]. Journal of Animal Science, 2017,95(Sup4): 276–277