William Foley is at the Dept of Zoology, James Cook University, Townsville, Queensland 4811, Australia.
Trends Ecol Evol. 1992 May;7(5):159-62. doi: 10.1016/0169-5347(92)90210-3.
Allometric considerations suggest that small mammals should be unable to eat highly fibrous diets. A combination of the selective and more rapid passage of fibrous material through the gut, together with changes in gut capacity when energy requirements increase, may allow small mammals to escape these allometric constraints. Recent evidence that birds can absorb essential amino acids from the caecum (which has hitherto been considered insignificant in mammals) suggests that birds and mammals have evolved very different ways to be a herbivore.
从生长律的角度来看，小型哺乳动物似乎无法食用高纤维的食物。但由于选择和快速通过消化道的纤维物质，以及在能量需求增加时消化道容量的变化，这可能使小型哺乳动物能够逃脱这些生长律的限制。最近的证据表明，鸟类可以从盲肠中吸收必需氨基酸（盲肠在哺乳动物中一直被认为是不重要的），这表明鸟类和哺乳动物已经进化出了非常不同的食草方式。
