Rumen chemical and bacterial changes during stepwise adaptation to a high-concentrate diet in goats.
Rumen chemical and bacterial changes during stepwise adaptation to a high-concentrate diet in goats.
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DOI：
10.1017/s175173110999111x
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
Yun-Zhang Sun;Sheng-Yong Mao;W. Zhu
中科院分区：
文献类型：
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作者：
Yun-Zhang Sun;Sheng-Yong Mao;W. Zhu
本试验研究了山羊在四阶段逐步适应高精料日粮（精料水平分别为0%、30%、50%和70%）过程中瘤胃化学物质和细菌变化的相关性。结果表明，从日粮I切换到II后，瘤胃pH从6.7降至5.5，并且在日粮III中维持在5.5左右。变性梯度凝胶电泳结果表明，除日粮由I型变为II型时出现3条带外，瘤胃细菌群落在最初3个饲养期内相对稳定，表明适宜的精料水平可以促进某些细菌的增殖。饲喂饲粮III 12天后，总挥发性脂肪酸（VFA）浓度和丁酸比例下降。在饲喂饲粮IV的第2天和第3天，瘤胃pH分别急剧下降至5.3和4.7，总VFA浓度进一步下降，而乳酸浓度显著增加，表明乳酸积累和瘤胃pH下降之间的关系。同时，许多细菌消失，包括大多数纤维溶解相关细菌，而牛链球菌和普雷沃菌样种占主导地位。有趣的是，在整个实验过程中，维持Succinivibrio dextrinosolvent样物种，表明其耐受低pH值。总之，瘤胃细菌群落是相对稳定的饲养0%至50%的精料，它被观察到，在日粮中适当的精料水平可以增加瘤胃细菌的多样性。然而，高精料日粮导致乳酸积累和瘤胃pH降低，导致大多数对低pH敏感的解纤相关细菌消失，而S。牛和普雷沃氏菌属继续存在。
The correlation between rumen chemical and bacterial changes was investigated during a four periodical stepwise adaptation to a high-concentrate diet (concentrate level at 0%, 30%, 50% and 70% for diet I to IV, respectively) in goats. The results showed that ruminal pH decreased from 6.7 to 5.5 after switching from diet I to II, and was maintained at about 5.5 on diet III. Denaturing gradient gel electrophoresis results showed that the rumen bacterial community was relatively stable during the initial three feeding periods, except for the appearance of three bands when diet changed from I to II, suggesting that an appropriate concentrate level can promote the proliferation of some bacteria. After 12 days of feeding diet III, total volatile fatty acid (VFA) concentration and butyrate proportion decreased. At days 2 and 3 of feeding diet IV, ruminal pH declined sharply to 5.3 and 4.7, respectively, and total VFA concentration decreased further while lactic acid concentration increased markedly, suggesting a relation between lactic acid accumulation and ruminal pH decline. At the same time, many bacteria disappeared, including most fibrolytic-related bacteria while Streptococcus bovis and Prevotella-like species dominated. Interestingly, Succinivibrio dextrinosolvens-like species maintained throughout the experiment, suggesting its tolerance to low pH. In conclusion, rumen bacterial community was relatively stable feeding 0% to 50% concentrate diets, and it was observed that appropriate concentrate levels in the diet could increase the diversity of rumen bacteria. However, concentrate-rich diets caused lactic acid accumulation and low ruminal pH that caused the disappearance of most fibrolytic-related bacteria sensitive to low pH while S. bovis and genus Prevotella persisted.