ABSTRACT The aim of this study was to assess differences of ruminal pH and rumination activity between the prepartal and postpartal period of cows and to investigate changes of feeding behaviour and ruminal fermentation depending on postpartal rations with slight differences in roughage energy and fibre concentration. Therefore, 11 rumen-cannulated German Holstein cows were used from 3 weeks antepartum until 16 weeks postpartum. During the dry period, all cows received the same diet. After calving cows were assigned to two groups receiving partial mixed rations with different energy concentrations (6.1 MJ NEL/kg DM [moderate], with 18% straw on dry matter [DM] basis, group MR) or 6.5 MJ NEL/kg DM [high], with 6% straw on DM basis, group HR). In both groups, concentrates were supplied on average at 45% of total DM intake. Circadian measurements of ruminal pH, ruminal temperature and rumination activity were conducted weekly during the transition period and bi-weekly after week 4 postpartum. Throughout the postpartal period, feed intake behaviour was measured, and twice during the experiment, rumen fluid composition and net-acid-base excretion in urine were determined. Mean ruminal pH, feeding behaviour, rumination activity and rumen fluid composition did not differ between the groups, whereas group HR exhibited higher diurnal variations of pH and had a lower rumen temperature than group MR postpartum. However, these differences also occurred during the prepartal period when groups received equal rations. It was observed that ruminal pH values and the risk for subacute ruminal acidosis (SARA) were increased during postpartal period, whereby the circadian pH values showed high cow-individual variations. Overall, differences of energy and fibre concentrations in roughage did not affect the observed variables, whereby it should be noted that the number of cows was quite low in this study. Our results suggest that the ruminal pH characteristics are rather cow individual, indicating that cows presumably differ in their susceptibility to develop SARA.

中文翻译：

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多产奶牛不同能量和粗饲料纤维浓度对泌乳早期瘤胃pH值、反刍活动和采食行为的影响

摘要 本研究的目的是评估奶牛产前和产后期间瘤胃 pH 值和反刍活动的差异，并研究饲喂行为和瘤胃发酵的变化取决于产后日粮，粗饲料能量和纤维浓度略有不同。因此，从产前 3 周到产后 16 周使用了 11 头瘤胃插管德国荷斯坦奶牛。在干奶期，所有奶牛都接受相同的饮食。产犊后的奶牛被分配到接受不同能量浓度的部分混合日粮（6.1 MJ NEL/kg DM [中等]，基于干物质 [DM] 含 18% 秸秆，MR 组）或 6.5 MJ NEL/kg DM [的两组]高]，以 DM 为基础添加 6% 的稻草，HR 组）。在两组中，浓缩物平均占 DM 总摄入量的 45%。在过渡期间每周进行一次瘤胃 pH、瘤胃温度和反刍活动的昼夜节律测量，产后第 4 周后每两周进行一次。在整个产后期间，测量采食行为，并在实验过程中两次测定瘤胃液成分和尿中的净酸碱排泄量。各组间的平均瘤胃 pH 值、摄食行为、反刍活动和瘤胃液成分没有差异，而 HR 组表现出更高的昼夜 pH 变化，并且瘤胃温度低于产后 MR 组。然而，这些差异也发生在产前阶段，当时各组收到了相等的口粮。据观察，产后瘤胃 pH 值和亚急性瘤胃酸中毒 (SARA) 的风险增加，因此，昼夜节律 pH 值显示出较高的奶牛个体差异。总体而言，粗饲料中能量和纤维浓度的差异不影响观察到的变量，因此应该注意本研究中奶牛的数量非常低。我们的结果表明瘤胃 pH 值特征与奶牛个体不同，这表明奶牛可能在发展 SARA 的易感性方面存在差异。