Dittmann Marie T, Hummel Jürgen, Hammer Sven, Arif Abdi, Hebel Christiana, Müller Dennis W H, Fritz Julia, Steuer Patrick, Schwarm Angela, Kreuzer Michael, Clauss Marcus
Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland; ETH Zurich, Institute for Agricultural Sciences, Universitätstrasse 2, 8092 Zurich, Switzerland.
Institute of Animal Science, University of Bonn, Endenicher Alleee 15, 53115 Bonn, Germany.
Comp Biochem Physiol A Mol Integr Physiol. 2015 Jul;185:58-68. doi: 10.1016/j.cbpa.2015.01.013. Epub 2015 Jan 28.
Digesta flow plays an important role in ruminant digestive physiology. We measured the mean retention time (MRT) of a solute and a particle marker in the gastrointestinal tract (GIT) and the reticulorumen (RR) of five gazelles and one dikdik species. Species-specific differences were independent from body mass (BM) or food intake. Comparative evaluations (including up to 31 other ruminant species) indicate that MRT GIT relate positively to BM, and are less related to feeding type (the percentage of grass in the natural diet, %grass) than MRT RR. The MRTparticleRR is related to BM and (as a trend) %grass, matching a higher RR capacity with increasing BM in grazers compared to browsers. MRTsoluteRR is neither linked to BM nor to %grass but shows a consistent phylogenetic signal. Selectivity factors (SF; MRTparticle/MRTsolute, proxies for the degree of digesta washing) are positively related to %grass, with a threshold effect, where species with >20% grass have higher SF. These findings suggest that in different ruminant taxa, morphophysiological adaptations controlling MRTsoluteRR evolved to achieve a similar SF RR in relation to a %grass threshold. A high SF could facilitate an increased microbial yield from the forestomach. Reasons for variation in SF above the %grass threshold might represent important drivers of ruminant diversification and await closer investigation.
食糜流动在反刍动物消化生理学中起着重要作用。我们测量了5只瞪羚和1只犬羚胃肠道（GIT）及瘤网胃（RR）中一种溶质和一种颗粒标记物的平均滞留时间（MRT）。物种特异性差异与体重（BM）或食物摄入量无关。比较评估（包括多达31种其他反刍动物物种）表明，GIT的MRT与BM呈正相关，且与RR的MRT相比，与采食类型（自然饮食中草的百分比，%草）的相关性较小。RR中颗粒的MRT与BM以及（呈一种趋势）%草相关，与食叶动物相比，食草动物中随着BM增加RR容量更高。RR中溶质的MRT既不与BM相关也不与%草相关，但显示出一致的系统发育信号。选择性因子（SF；颗粒MRT/溶质MRT，食糜冲洗程度的代理指标）与%草呈正相关，具有阈值效应，即草含量>20%的物种具有更高的SF。这些发现表明，在不同的反刍动物类群中，控制RR中溶质MRT的形态生理适应进化是为了在%草阈值方面实现相似的RR SF。高SF可能有助于提高前胃的微生物产量。%草阈值以上SF变化的原因可能是反刍动物多样化的重要驱动因素，有待进一步深入研究。
