Optimizing rumen functions in the close-up transition period and early lactation to drive dry matter intake and energy balance in cows
Optimizing rumen functions in the close-up transition period and early lactation to drive dry matter intake and energy balance in cows
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DOI：
10.1016/j.anireprosci.2006.08.005
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发表时间：
2006-12-01
影响因子：
2.2
通讯作者：
Jouany, J. -P.
中科院分区：
文献类型：
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作者：
Jouany, J. -P.
与过渡期和泌乳早期的能量需求相比，能量摄入量的巨大不足意味着高产奶牛需要能量密集型日粮。高淀粉日粮在瘤胃微生物生态系统的强烈发酵下，产生大量的VFA，导致pH值下降和乳酸积累，加剧pH值下降，被认为是引起瘤胃酸中毒的主要原因。这种瘤胃功能障碍会影响瘤胃微生物，导致消化效率降低，从而减少采食量，加剧奶牛能量不足。限制酸中毒风险的主要方法是通过饮食管理。因此，在产犊前的3周内，动物必须逐渐适应谷物成分。此外，日粮管理策略将优先考虑低降解淀粉，并在日粮中包括足够的纤维以刺激反刍和流涎。化学添加剂可用于防止瘤胃酸中毒。瘤胃pH值可以通过直接添加1-2% DM摄入量的化学缓冲剂来控制。代谢氢可以通过特定的代谢途径（如丙酸生成）动员，以与乳酸的合成竞争。这可以通过添加丙酸盐前体如天冬氨酸盐、苹果酸盐或富马酸盐来实现。然而，这些添加剂在经济上是不可行的，并且不容易被消费者接受。益生菌主要以活酵母的形式提供，必须被视为预防亚急性酸中毒的解决方案，但它们不被认为是急性酸中毒的有效治疗方法。虽然益生菌的作用机制尚未完全了解，本文提出了一个合理的模型，他们的行动模式。最近，基于植物提取物的添加剂已被提出作为优化瘤胃功能的解决方案，但在这些添加剂上市之前，需要进一步的功效研究和安全性试验。已经建议添加纤维溶解酶以改善酸中毒期间膳食纤维部分的消化。虽然迄今为止所取得的结果是令人鼓舞的，需要对这些酶进行更多的反刍动物特异性研究。一些抗生素是革兰氏阳性菌的潜在抑制剂，革兰氏阳性菌与瘤胃酸中毒有关，但它们作为饲料添加剂的使用已被欧盟从2006年1月1日起禁止。(c)2006 Elsevier B. V.保留所有权利。
The large deficit in energy intake in relation to energy requirements during the transition and early lactation periods means that high-producing cows need energy-dense rations. High-starch diets are intensively fermented by the microbial ecosystem in the rumen, giving rise to a high production of VFAs and resulting in a drop in pH and the accumulation of lactic acid, which exacerbates the decline in PH and is considered as the major cause of rumen acidosis. This rumen dysfunction affects rumen microbes and results in less efficient digestion, thereby decreasing feed intake and exacerbating the energy deficit in the cows.The main way to limit the risk of acidosis is by diet management. Thus, animals must be progressively adapted to grain ingredients during the 3-week period before calving. Furthermore, the diet management strategy will be to privilege low-degradable starch and include enough fiber in the diet to stimulate rumination and salivation.Chemical additives can be used to prevent rumen acidosis. Rumen pH can be controlled by direct addition of chemical buffers at doses of 1-2% of DM intake. Metabolic hydrogen can be mobilized through specific metabolic pathways such as propionogenesis to compete with the synthesis of lactic acid. This can be achieved by adding propionate precursors such as aspartate, malate or fumarate. However, these additives are not economically viable, and will not easily be accepted by consumers. Probiotics, which are mainly supplied as live yeasts, have to be regarded as a solution for preventing subacute acidosis but they are not considered as an efficient cure for acute acidosis. Although the mechanisms of action of probiotics are not fully understood, this paper proposes a plausible model of their mode of action. Recently, additives based on plant extracts have been proposed as a solution for optimizing rumen functions, but further efficacy studies and safety trials are required before these additives can be marketed. The addition of fibrolytic enzymes has been suggested to improve the digestion of the dietary fiber fraction during acidosis. Although the results obtained so far are encouraging, more ruminant-specific research needs to be carried out on these enzymes.Some antibiotics are potential inhibitors of Gram-positive bacteria, which are involved in rumen acidosis, but their use as feed additives has been banned from 01/01/2006 in the EU. (c) 2006 Elsevier B.V. All rights reserved.