Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation in heifers
Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation in heifers
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DOI：
10.2527/jas.2008-1184
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发表时间：
2009-05-01
影响因子：
3.3
通讯作者：
Wallace, R. J.
中科院分区：
文献类型：
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作者：
Blanch, M.;Calsamiglia, S.;Wallace, R. J.
在一个完全随机的实验中，使用12头杂交小母牛（452 +/- 20 kg BW）研究了酸中毒诱导期间瘤胃发酵的生理变化及其使用多价多克隆抗体制剂（PAP）的控制。治疗为对照（CTR）或PAP。酸中毒诱导方案包括3个阶段：3个月的100%牛毛草干草，供自由采食，10天（从实验第1天到第10天）对治疗的适应治疗组（100%饲料喂养+PAP 10 mL/d外敷），5 d（从实验的第11天到第15天）的转变，包括增加浓缩物（16.5% CP）2.5 kg/d至12.5 kg/d，同时保持自由采食牛毛草并向给药小母牛提供10 mL/d PAP。保持12.5 kg/d的浓缩饲料，直至小母牛出现酸中毒（实验第16天至第22天）。当动物被认为酸中毒时，将其改为50：50的饲料：浓缩物饮食，监测4天，并从实验中移除。在饲喂前和饲喂后6 h采集瘤胃液样品，测定pH、VFA、乳酸盐、原虫计数，并提取DNA进行实时定量PCR和变性梯度凝胶电泳分析。仅分析了在适应治疗期间、酸中毒前3天和1天、酸中毒当天以及酸中毒后1天和4天采集的样本。差异被宣布为P < 0.05。小母牛（CTR为83%，PAP为50%）在过渡开始后5.25 +/- 0.17 d进入酸中毒。酸中毒动物的发酵特征在处理之间相似。从酸中毒前3天到酸中毒当天，观察到pH值和乙酸-丙酸比下降，总VFA、丁酸盐和内甲藻形态计数增加。然而，牛链球菌和埃氏巨球菌的最大浓度（分别为79 +/- 54和104 +/- 73 ng DNA/mL瘤胃液）和瘤胃内毒素的减少（分别为10.6和6.46 kg）在酸中毒后1天记录。与CTR小母牛相比，饲喂PAP的小母牛在开始饲喂挑战后第6天（6.70 vs. 6.11）、第8天（6.54 vs. 5.95）和第9天（7.26 vs. 6.59）饲喂前的pH值更高。饲喂PAP的小母牛的总VFA浓度往往高于CTR（分别为124和114 +/- 4.0 mM）。这些结果表明，PAP可能是有效的控制酸中毒的小母牛在快速过渡到高浓度的饮食。
Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation (PAP) were studied in a completely randomized experiment using 12 crossbred heifers (452 +/- 20 kg of BW). Treatments were control (CTR) or PAP. The acidosis induction protocol consisted of 3 periods: 3 mo of 100% fescue hay fed for ad libitum intake, 10 d (from d 1 to 10 of the experiment) of adaptation to the treatment (100% forage feeding + 10 mL/d of PAP top-dressed to the treatment group), and 5 d (from d 11 to 15 of the experiment) of transition, which consisted of increasing the concentrate (16.5% CP) 2.5 kg/d up to 12.5 kg/d while maintaining ad libitum intake of fescue and providing 10 mL/d of PAP to the treated heifers. Concentrate feeding of 12.5 kg/d was maintained until heifers developed acidosis (from d 16 to 22 of the experiment). When an animal was considered acidotic, it was changed to a 50: 50 forage: concentrate diet, monitored for 4 d, and removed from the experiment. Samples of ruminal fluid were collected before and 6 h after feeding to determine pH, VFA, lactate, protozoa counts, and DNA extraction for quantitative real-time PCR and denaturing gradient gel electrophoresis analyses. Only samples collected during adaptation to the treatment, at 3 and 1 d before acidosis, on the acidosis day, and at 1 and 4 d after acidosis were analyzed. Differences were declared at P < 0.05. Heifers (83% for CTR, and 50% for PAP) entered into acidosis 5.25 +/- 0.17 d after the beginning of the transition. The fermentation profile of animals with acidosis was similar between treatments. From 3 d before acidosis to acidosis day, decreases in pH and in acetate-to-propionate ratio and increases in total VFA, butyrate, and entodiniomorph counts were observed. However, the greatest concentrations of Streptococcus bovis and Megasphaera elsdenii (79 +/- 54 and 104 +/- 73 ng of DNA/mL of ruminal fluid, respectively) and a decrease in DMI (10.6 vs. 6.46 kg, respectively) were recorded 1 d after acidosis. Compared with CTR heifers, heifers fed PAP had greater pH before feeding on d 6 (6.70 vs. 6.11), 8 (6.54 vs. 5.95), and 9 (7.26 vs. 6.59) after the beginning of the feeding challenge. Heifers fed PAP tended to have greater total VFA concentrations than CTR (124 and 114 +/- 4.0 mM, respectively). These results indicate that PAP may be effective in controlling acidosis of heifers during a rapid transition to a high-concentrate diet.