Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Switzerland.
Comp Biochem Physiol A Mol Integr Physiol. 2011 Jul;159(3):284-90. doi: 10.1016/j.cbpa.2011.03.020. Epub 2011 Mar 30.
Morphological characteristics of the forestomach, as well as reports of a natural diet that mostly excludes monocots, suggest that dikdiks (Madoqua spp.), among smallest extant ruminants, should have a 'moose-type' forestomach physiology characterised by a low degree of selective particle retention. We tested this assumption in a series of feeding experiments with 12 adult Phillip's dikdiks (Madoqua saltiana phillipsi) on three different intake levels per animal, using cobalt-EDTA as a solute marker and a 'conventional' chromium-mordanted fibre (<2 mm; mean particle size 0.63 mm) marker for the particle phase. Body mass had no influence on retention measurements, whereas food intake level clearly had. Drinking water intake was not related to the retention of the solute marker. In contrast to our expectations, the particle marker was retained distinctively longer than the solute marker. Comparisons with results in larger ruminants and with faecal particle sizes measured in dikdiks suggested that in these small animals, the chosen particle marker was above the critical size threshold, above which particle delay in the forestomach is not only due to selective particle retention (as compared to fluids), but additionally due to the ruminal particle sorting mechanism that retains particles above this threshold longer than particles below this threshold. A second study with a similar marker of a lower mean particle size (0.17 mm, which is below the faecal particle size reported for dikdiks) resulted in particle and fluid retention patterns similar to those documented in other 'moose-type' ruminants. Nevertheless, even this smaller particle marker yielded retention times that were longer than those predicted by allometric equations based on quarter-power scaling, providing further support for observations that small ruminants generally achieve longer retention times and higher digestive efficiencies than expected based on their body size.
前胃的形态特征，以及报告的主要排除单子叶植物的自然饮食，表明在最小的现存反刍动物中，跳羚（Madoqua 属）的前胃生理学应该具有“驼鹿型”特征，其特征是选择性颗粒保留程度低。我们在一系列喂食实验中用 12 只成年菲利普跳羚（Madoqua saltiana phillipsi）进行了测试，每个动物有三个不同的摄入水平，使用钴-EDTA 作为溶质标记物和“传统”铬鞣纤维（<2 毫米；平均粒径 0.63 毫米）标记物用于颗粒相。体重对保留测量没有影响，而食物摄入量水平则有明显影响。饮用水摄入量与溶质标记物的保留无关。与我们的预期相反，颗粒标记物的保留时间明显长于溶质标记物。与较大反刍动物的结果和在跳羚中测量的粪便颗粒大小进行比较表明，在这些小动物中，所选的颗粒标记物超过了临界尺寸阈值，在这个阈值之上，前胃中的颗粒延迟不仅是由于选择性颗粒保留（与流体相比），而且还由于瘤胃颗粒分选机制，该机制将大于此阈值的颗粒保留的时间长于小于此阈值的颗粒。第二项使用平均粒径较低的类似标记物（0.17 毫米，低于报告的跳羚粪便颗粒大小）的研究导致颗粒和流体保留模式与其他“驼鹿型”反刍动物记录的模式相似。然而，即使是这个较小的颗粒标记物也产生了比基于四分之一幂缩放的体尺方程预测的更长的保留时间，这进一步支持了这样的观察结果，即小型反刍动物通常比基于其体型预期的保留时间更长，消化效率更高。
