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首页> 外文期刊>Mammal Review >The digestive performance of mammalian herbivores: why big may not be that much better
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The digestive performance of mammalian herbivores: why big may not be that much better

机译：哺乳动物食草动物的消化性能：为什么大食草动物可能没有那么好

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1. A traditional approach to the nutritional ecology of herbivores is that larger animals can tolerate a diet of lesser quality due to a higher digestive efficiency bestowed on them by comparatively long ingesta retention times and lower relative energy requirements. 2. There are important physiological disadvantages that larger animals must compensate for, namely a lower gut surface: gut volume ratio, larger ingesta particle size and greater losses of faecal bacterial material due to more fermentation. Compensating adaptations could include an increased surface enlargement in larger animals, increased absorption rates per unit of gut surface, and increased gut motility to enhance mixing of ingesta. 3. A lower surface: volume ratio, particularly insacciform forestomach structures, could be a reason for the fact that methane production is of significant scope mainly in large herbivores and not in small herbivores with comparably long retention times; in the latter, the substrate for methanogenesis- the volatile fatty acids - could be absorbed faster due to a more favourable gut surface: volume ratio. 4. Existing data suggest that in herbivores, an increase in fibre digestibility is not necessarily accompanied by an increase in overall apparent dry matter digestibility. This indicates a comparative decrease of the apparent digestibility of non-fibre material, either due to a lesser utilization of non-fibre substrate or an increased loss of endogenous/bacterial substance. Quantitative research onthese mechanisms is warranted in order to evaluate whether an increase in body size represents a net increase of digestive efficiency or just a shift of digestive focus.
机译：1.食草动物营养生态学的传统方法是，较大的动物由于相对较长的摄食时间和较低的相对能量需求而具有较高的消化效率，因此可以忍受较低质量的饮食。 2.较大的动物必须弥补其重要的生理缺陷，即较低的肠道表面：肠道体积比，较大的摄入颗粒大小以及由于更多的发酵而增加的粪便细菌物质损失。补偿性适应措施可能包括增加大型动物的表面面积，增加每单位肠道表面的吸收率，以及增加肠道运动性以增强消化混合。 3.较低的表面：体积比，特别是不光滑的前庭结构，可能是以下事实的原因：甲烷的生产范围很广，主要存在于大型草食动物中，而不是具有较长保留时间的小型草食动物;在后者中，由于更有利的肠道表面：体积比，甲烷化作用的底物-挥发性脂肪酸-可以更快地被吸收。 4.现有数据表明，在草食动物中，纤维消化率的提高不一定伴随着总表观干物质消化率的提高。这表明由于非纤维底物的利用率降低或内源性/细菌性物质损失增加，非纤维材料的表观消化率相对下降。这些机制的定量研究是必要的，以便评估体重增加是消化效率的净增加还是仅仅是消化重心的转移。

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