The general observation that secondary consumers ingest highly digestible food and have simple short guts and small abdominal cavities intuitively results in the assumption that mammalian carnivores carry less digesta in their gut compared to herbivores. Due to logistic constraints, this assumption has not been tested quantitatively so far. In this contribution, we estimated the dry matter gut contents (DMC) for 25 species of the order Carnivora (including two strictly herbivorous ones, the giant and the red panda) using the physical 'Occupancy Principle', based on a literature data collection on dry matter intake (DMI), apparent dry matter digestibility (aD DM) and retention time (RT), and compared the results to an existing collection for herbivores. Scaling exponents with body mass (BM) for both carnivores and herbivores were in the same range with DMI ~ BM0.75; aD DM ~ BM0; RT ~ BM0.11 and DMC ~ BM0.88. The trophic level (carnivore vs herbivore) significantly affected all digestive physiology parameters except for RT. Numerically, the carnivore DMI level reached 77%, the RT 32% and DMC only 29% of the corresponding herbivore values, whereas the herbivore aD DM only reached 82% of that of carnivores. Thus, we quantitatively show that carnivores carry less inert mass or gut content compared to herbivores, which putatively benefits them in predator-prey interactions and might have contributed to the evolution towards unguligradism in herbivores. As expected, the two panda species appeared as outliers in the dataset with low aD DM and RT for a herbivore but extremely high DMI values, resulting in DMC in the lower part of the herbivore range. Whereas the difference in DMI and DMC scaling in herbivores might allow larger herbivores to compensate for lower diet quality by ingesting more, this difference may allow larger carnivores not to go for less digestible prey parts, but mainly to increase meal intervals, i.e. not having to hunt on a daily basis.

中文翻译：

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食肉动物和猎物之间的重量分布不均：比较陆生食草动物和食肉动物之间的肠道填充。

一般观察认为，次要消费者摄入易消化的食物，且肠道短而腹腔小，直观地得出这样的假设：与食草动物相比，哺乳动物的食肉动物的肠道消化率较低。由于后勤方面的限制，目前尚未对该假设进行定量测试。在这项贡献中，我们根据自然资源的“占用原则”估算了食肉动物（包括食肉动物，包括大熊猫和小熊猫在内的两种食肉动物）的25种干物质肠道含量（DMC）。干物质摄入量（DMI），表观干物质消化率（aD DM）和保留时间（RT），并将结果与​​现有食草动物集合进行比较。食肉动物和食草动物的体重指数（BM）在相同范围内，DMI〜BM0.75。DM〜BM0; RT〜BM0.11和DMC〜BM0.88。营养水平（食肉动物与草食动物）显着影响除RT外的所有消化生理参数。在数字上，食肉动物的DMI水平达到相应食草动物值的77％，RT 32％和DMC仅达到食草动物值的29％，而食草动物aD DM仅达到食肉动物的82％。因此，我们定量地显示，食肉动物比食草动物具有较少的惰性质量或肠道含量，这在食肉动物与猎物的相互作用中可能使食肉动物受益，并且可能促进了食草动物向非肉食动物进化。正如预期的那样，这两个熊猫物种在数据集中表现为离群值，对于草食动物而言，其aD DM和RT较低，但DMI值却极高，导致DMC在草食动物范围的下部。食草动物的DMI和DMC缩放比例的差异可能使较大的食草动物通过摄入更多的食物来补偿较低的饮食质量，但这种差异可能使较大的食肉动物不去消化易消化的猎物，而主要是增加进餐间隔，即不必每天狩猎。